Download EXAM 2 Lecture 15 1. What are cofactors? A: They are small organic

EXAM 2
Lecture 15
1. What are cofactors?
A: They are small organic molecules or ions that work in concert with an enzyme to catalyze
biochemical reactions. They provide special chemical reactivity or structural properties that
can drive these special reactions.
2. What are the two subdivisions of cofactors?
A: Essential ions and coenzymes
3. What are the further subdivisions of essential ions and how strong do they bind?
A: Activator ions (loosely bound) and metal ions of metalloenzymes (tightly bound)
4. What are the further subdivisions of coenzymes and how strong do they bind?
A: Cosubstrates (loosely bound) and prosthetic groups (tightly bound)
5. What does it mean to be loosely bound? What are two examples he provided?
A: molecule or ion will bind to the enzyme, carry out reaction, then dissociate from the
enzyme; ATP and Mg2+
6. What does it mean to be tightly bound? What are five examples he provided?
A: may be covalently attached to an enzyme residue in the active site or bind non-covalently
with a very high affinity; heme, biotin, lipoic acid, flavins, and Zn2+ ions
7. What are major metabolite cofactors?
A: Molecules that are produced by metabolic pathways that are used by other enzymes to
carry out key reactions.
8. What is ATP major metabolic role? Mechanistic role?
A: transfer of phosphoryl or nucleotidyl groups/used as an energy donor by dozens of
enzymes; cosubstrates
9. What is S-Adenosylmethionine (SAM) major metabolic role? Mechanistic role?
A: donates a methyl group in nearly all biochemical reactions requiring a methyl group
transfer; cosubstrates
10. What is UDP-glucose major metabolic role?
A: Glycogen synthesis
11. What are GTP, UTP, CTP, ATP, and TTP major metabolic role?
A: DNA synthesis
12. What are the two ways vitamins are used?
A: They are used “as-is” when we consume them or most are transformed before they are
used.
13. How does vitamin C act as a coenzyme?
A: It donates electrons to reduce targets
14. What is Nicotinamide adenine dinucleotide (NAD+)/Nicotinamide adenine dinucleotide
phosphate (NADP+) major metabolic role? Mechanistic? Vitamin source?
A: They donate or accept one proton and two electrons as a hydride ion (H: - ). They are
commonly used by dehydrogenase enzymes; Cosubstrates; Niacin (vitamin B3)
15. What is NADH biggest role? NADPH?
A: Carry electrons to mitochondria to drive ATP production; used in fatty acid and
cholesterol synthesis
16. What is Flavin mononucleotide (FMN)/Flavin adenine dinucleotide (FAD) major metabolic role?
Mechanistic role? Vitamin source?
A: Oxidation-reduction reactions involving one- and two-electron transfer; prosthetic group;
Riboflavin (vitamin B2)
17. What is FMN/FAD biggest role in the body?
A: Electron transport in mitochondria to drive ATP production
18. What is Coenzyme A (CoA) major metabolic role? Mechanistic role? Vitamin source?
A: Transfer of acyl groups; cosubstrates; pantothenate (vitamin B5)
19. How is the acyl group activated for reactivity?
A: A sulfur atom on CoA works with the carbonyl group of the acyl group
20. What is one of the most common cofactors used by metabolic pathways?
A: CoA
21. What is Thiamine pyrophosphate (TPP) major metabolic role? Mechanistic role? Vitamin source?
A: transfer of two-carbon fragments containing a carbonyl group; prosthetic group;
Thiamine (vitamin B1)
22. What two reactions are used to produce the aldehyde groups in TPP?
A: Decarboxylation and transketolation
23. What is the major function of TPP in the body?
A: Energy metabolism, essential for neuronal and neurocognitive function
24. TPP is used in the synthesis of what molecules?
A: Acetylcholine, nucleic acids, and NADPH
25. What is Pyridoxyl phosphate (PLP) major metabolic role? Mechanistic role? Vitamin source?
A: Transfer of groups to and from amino acids; prosthetic group; Pyridoxine (vitamin B6)
26. What is the functional center of PLP?
A: an aldehyde group
27. How does PLP attach to the host enzyme?
A: covalently
28. What can PLP function depend on?
A: NADH, cobalamin, and folic acid
29. What is Biotin major metabolic role? Mechanistic role? Vitamin source?
A: ATP-dependent carboxylation of substrates or carboxyl group transfer between
substrates; prosthetic group; biotin (vitamin B7)
30. Is biotin a vitamin that is used as-is or does it undergo transformation? How?
A: As-is after it is covalently attached to an enzyme lysine
31. Why is biotin very important in metabolism (2 reasons)?
A: Transforms PEP to oxaloacetate and transforms acetyl CoA to malonyl CoA for fatty acid
synthesis
32. What is tetrahydrofolate (THF) major metabolic role? Mechanistic role? Vitamin source?
A: Transfer of one carbon units in the form of methyl (CH3), methylene (CH2), and methenyl
(CH). Also provides methyl group for thymine in DNA; cosubstrates; Folic acid (vitamin B9)
33. What are the sites of function in THF?
A: The two nitrogen atoms
34. What is THF critical for?
A: neurological function, neurological development in fetus, synthesis of methionine,
synthesis of nucleic acids
35. How does THF work?
A: Other cofactors work with THF to produce the carbon in the required form. Once formed,
THF can donate the single carbon to target molecule and can accept single carbons
36. What is Lipoamide major metabolic role? Mechanistic role?
A: oxidation of a hydroxyl group from TPP and subsequent transfer as an acyl group;
prosthetic group
37. What is Lipoamide formed from and how?
A: Formed from lipoic acid when attached to a protein Lys side chain
38. What are lipoamide redox properties? What is produced when lipoamide is oxidized?
A: Ring form with S—S bond is oxidized form; Ring form with –SH groups is reduced form;
NADH is produced from NAD+ when oxidized
39. What is adenosylcobalamin major metabolic role? Mechanistic role? Vitamin source?
A: Catalyzes exchange reactions (i.e. isomerizations); prosthetic group; cobalamin (vitamin
B12)
40. What is methylcobalamin major metabolic role? Mechanistic role? Vitamin source?
A: Transfer of methyl groups; prosthetic group; cobalamin (vitamin B12)
41. What drives the reactions that forms methionine from homocysteine? Where is the cofactor
found?
A: methylcobalamin; in the active site of the enzyme
42. What is Retinal major metabolic role? Mechanistic role? Vitamin source?
A: Vision; prosthetic group; Vitamin A
43. What is vitamin K major metabolic role? Mechanistic role?
A: It is used in the synthesis of some blood clotting protein and the carboxylation of some
glutmate residues; prosthetic group
44. What is Vitamin E main characteristic?
A: Anti-oxidant properties
45. What is vitamin D major role?
A: Assist with the uptake of Ca2+
46. What is heme mechanistic role?
A: Prosthetic group
47. What is heme function?
A: involved in electron transfer in electron transport chain and is key component in
hemoglobin
48. What are the two tightly bound metals discussed?
A: Iron-Sulfur clusters and Zn2+ ions
49. What is iron-sulfur clusters function?
A: Electron transfer reactions, especially those in the ETC and the TCA cycle
50. What is Zn2+ ions function?
A: They often form the electrostatic interactions with substrates to control position of the
substrate or to activate a bond or reactive group
LECTURE 16
1. What is the glycocalyx?
A: It is a network of glycoproteins and proteoglycans that extends outward from the surface
of cells.
2. What is another structure the glycocalyx is related to?
A: Extracellular matrix
3. What is the function of the glycocalyx?
A: It protects the outer surface of the cell from mechanical disruption and allows for cells to
attach itself to other surfaces. It is unique to every individual and serves as a key mechanism
for immune system to identify, which cells belong and which are foreign.
4. What are some mammalian cells that have a glycocalyx? What is its function?
A:
 Mature platelets—allows them to adhere to injury site
 Vascular endothelial cells—reduces friction of blood flow
 Sperm cells—allows them to adhere to ovum
 Fertilized ovum—allows it to adhere to uterine lining
 Cancer cells have a unique glycocalyx structure that allows them to be identified
against normal cells
5. What are glycosaminoglycans (GAGs)?
A: they are heteroglycans with linear, regular repeating disaccharide units
6. What are the five classes of GAGs?
A:
 Hyaluronic acid (HA)
 Condroitin sulfates (CS)
 Heparin and heparin sulfates (HS)
 Keratan sulfate (KS)
 Dermatin sulfate (DS)
7. What are the two types monosaccharides found in GAGs?
A: One is an amino sugar (glucosamine or galactosamine), which is acetylated except in
heparin where it is sulfate. The other is an alduronic acid (glucuronic acid and/or its isomer
iduronic acid) except KS where it is galactose.
8. All GAGs except what have hydroxyls substituted with sulfate?
A: Hyaluronic acid
9. What allows sequences to have specific recognition functions?
A: Multiple sulfation
10. GAGs attach to core proteins to form what?
A: Proteoglycan
11. GAGs are linked to serine or threonine residues how?
A: Glycosidic linkage (O-linked)
12. Proteoglycans are predominantly…protein or carbohydrate?
A: Carbohydrate
13. What are proteoglycans?
A: A core protein attached to many long, linear chains of GAGs
14. What is proteoglycan function?
A: They are the key component of extracellular matrix and interacts directly with proteins of
the ECM: collagen, fibronectin, and laminin. They form the meshwork that limits exposure of
cell surface to various agents. Acts as a lubricant and shock absorber
15. Where are proteoglycans found?
A: Synovial fluid of joints, vitreous humor of the eye, arterial walls, bone, and cartilage
16. What type of structure do proteoglycans have?
A: Bottle/Bristle-Brush
17. What leads to charge repulsion and GAGs being very extended molecules?
A: the presence of many negative charges
18. What causes GAGs to be highly hydrated?
A: the charged groups and –OH groups
19. What are the two forms of glycoproteins?
A: N-linked and O-linked
20. Where are glycoproteins found?
A: In the cell membrane and in the blood
21. N-linked saccharides are attached via the amide nitrogen of what amino acid residue?
A: Asparagine
22. O-linked saccharides are attached to hydroxyl group of what?
A: Serine, Threonine, or hydroxylysine
23. Amino sugars contain what in the place of one of the hydroxyl groups?
A: Amine group
24. What glycoproteins are more complex, highly varied structure, and signal location/function?
A: N-linked
25. What glycoproteins are simpler, 1-3 sugars, and affect recognition and structure?
A: O-linked
26. What is the function of O-linked saccharides of glycoproteins?
A: in many cases, to force protein to adopt an extended conformation
27. What are the two roles of the bristle brush structure?
A: Protective role—to keep agents away from cell surface; Receptor role—easier for agents
to find a receptor above the complicated ECM
28. What is the function of N-linked oligosaccharides?
A: alter the chemical and physical properties of proteins and stabilize protein conformations
and/or protect against proteolysis
29. How do N-linked glycoproteins, in blood, target them for degradation in the liver?
A: Cleavage of monosaccharide units from N-linked glycoprotein
30. What is mucopolysaccharidoses?
A: Enzyme deficiency in the metabolism/degradation of GAGs
31. What can occur from a result of defective/deficient enzymes in lysosomes?
A: GAGs building on inside cells, organs and blood. Eventually could cause cellular damage,
dysfunctional development, or retardation in children
32. What is the ECM?
A: Fibrous proteins embedded in amorphous “ground substance” that has three major
components
33. What are the three major components of ECM? What is found in each?
A:
 Ground substance—hyaluronic acid (huge hydrated GAG polysaccharide),
proteoglycans, adhesive proteins, laminin, and fibronectin
 Integrins—integral membrane proteins in PM that bind to adhesive proteins, span
the membrane to provide contact between ECM and cytoskeleton
 Matrix metalloproteinases (MMPs)—enzymes that cleave one or more components
of the ECM
34. Which component of the ECM is responsible for normal and pathological tissue remodeling?
A: Matrix metalloproteinases
35. What is the difference between fibrous proteins and ground substance?
A: Fibrous proteins provide tensile strength and elasticity and ground substance provides
deformability, resilience and cohesion
36. What functions to communicate extracellular matrix events to the cell cytoskeletal network?
A: Integrins
37. What is the cytoskeleton and what is its function?
A: It is protein scaffolding consisting of actin filaments and microtubules. It functions in
maintaining cell shape, transporting cell components around cell, and is the key for cell
movement
38. What disease is a result of fibrosis due to thickening of the ECM?
A: Chronic Obstructive Pulmonary Disease (COPD)
39. What disease is a result of an error in collagen fibril assembly?
A: Ehlers-Danlos syndrome
40. What is Alport syndrome?
A: It is a defect in collagen synthesis/assembly needed to make the basement membrane in
kidneys. The basement membrane loses ECM protein and fine morphological structure, this
affects kidney glomerulus where blood is filtered
41. What causes Marfan’s syndrome?
A: A defect in fibrillin-1, which can bind to transforming growth factor B (TGF-B), which
controls cell growth
LECTURE 17
1. What molecules can passively diffuse through the lipid bilayer?
A: small polar molecules, nonpolar gases, and lipophilic molecules
2. What is equivalence?
A: The mole concentration divided by the absolute value of the valence
3. What is membrane flux? How is it defined?
A: The movement of substances across membranes. Flux (J) is defined in terms of the
number of units moving across a given area per unit time; J is most often moles/sec/cm 2.
4. What is simple diffusion?
A: Freely diffusible molecules can rapidly equilibrate across the membrane
5. What is facilitated diffusion?
A: Charged and polar molecules cannot freely equilibrate and require specific transport
mechanisms
6. What are some general characteristics of membrane transport?
A:
 Substances flow from high conc. to low conc.
 Non-polar substances can pass directly through bilayer
 Polar or uncharged substances require a transport protein to provide a path
through the membrane
 To transport substances against the electrochemical gradient, energy is require
7. What is the driving force for transport?
A: The chemical potential
8. What must ΔG° be for the reaction to be spontaneous? Non-spontaneous?
A: Negative; positive
9. Is sodium conc. higher extracellular or intracellular? Potassium? Calcium?
A: Extracellular; intracellular; extracellular
10. Describe the potassium electrochemical potential.
A: In the diagram, there is unequal [KCl] but charge is balance on each side. The membrane
between the two sides is permeable for K+ ions only. K+ ions will move from areas of high to
low conc. Electrical potential develops as positive charge builds up. Eventually, the
electrical potential will balance the chemical potential
11. Cell membrane potentials depend on what?
A: Ionic concentration gradients
12. Define the membrane potential.
A: It is the difference in charge, Vm (membrane voltage)
13. What is the resting membrane potential according to the Nernst equation?
A: -95mV
14. Simple diffusion is driven by what?
A: Concentration gradient
15. List the solute factors that affect simple diffusion.
A:
 Size—must be small
 Uncharged—electroneutral
 Nonpolar—relatively hydrophobic
 Concentration—always high to low
 Temperature—as temperature increases so does the kinetic energy of a solute
 The permeability coefficient
16. What are the two parameters of the function of the permeability coefficient?
A: Partition coefficient (how readily the solute dissolves in lipid phase of bilayer) and
diffusion coefficient (how readily the solute traverses the lipid phase of bilayer)
17. What does it mean that the rate of diffusion is inversely related to the molecular ratio?
A: The smaller the solute diameter, the larger the diffusion coefficient and vice versa
18. What does permeability directly affect?
A: Membrane flux (J)
19. What are the three factors permeability depends on?
A: Ki—the partition coefficient; Di—the diffusion coefficient; Δx—the area available for
diffusion
20. What structure allows for some polar and charged molecules to simple diffuse across the
membrane?
A: Pore proteins
21. What drives facilitated diffusion?
A: Energy of electrochemical gradient
22. What are some examples of specificity in facilitated diffusion?
A: Na+ ions pass through Na+ channels, but K+ generally don’t pass through Na+ channels;
Cationic amino acids pass through cationic amino acid transporters but hydrophobic amino
acids don’t
23. What pores open and closed based on stimuli?
A: Gated pores
24. Carriers change affinity for substrate based on what?
A: conformational changes
25. What is the difference in the graphs for simple and facilitated diffusion?
A: Simple is diagonal, linear; Facilitated is hyperbolic because it can reach it a maximum
26. Describe the process of glucose transport into RBCs and how it keeps from diffusing back out.
A: Glucose enters RBC by passive transport through a pore. As soon as the glucose is in the
cell it is phosphorylated, which keeps it from leaving the cell
27. What is active transport?
A: Transport against the electrochemical gradient that requires energy input to overcome
the positive ΔG° for the process.
28. How does the sodium pump function?
A: It uses ATP energy to transport 3 Na+ ions out of the cell and 2 K+ ions into the cell, thus
setting up an inward Na+ gradient and an outward K+ gradient
29. What is the sodium pump important for?
A: Nerve transmission, action potential, and epithelial cell functions
30. What does it mean for the membrane to be electrogenic? Give an example.
A: Having a net flow change in membrane potential. Net flow of 1+ out of the cell for the
sodium pump
31. What type of pump is the sodium pump?
A: Ion pump
32. What are two other examples of ion pumps and where do they typically function?
A: Calcium pump—maintains a Ca2+ gradient in muscles, nerves, and other places. Proton
pump—maintains proton gradient in the stomach
33. What is cotransport? What is another name for it?
A: Cotransport is when the transport of one substance along its electrochemical gradient can
be used to transport another substance against its gradient. They require a primary active
transport system; Secondary active transport
34. What is the word for transport in the same direction? Opposite direction?
A: Symport; antiport
35. Does secondary transport require ATP?
A: Directly…no. Indirectly…yes. Secondary transport requires a primary active transport,
which requires ATP.
36. Describe the secondary active transport of glucose.
A: The sodium pump maintains a Na+ gradientThe inward Na+ gradient provides energy
to drive active transport of glucose into the cellglucose leaves the cell by facilitated
diffusion at a different transporter
37. How does GLUT 1-5 work?
A:
 GLUT 1—it is expressed in cell types with barrier functions; it is a high affinity
glucose transport system
 GLUT 2—it is a high capacity, low affinity transporter that may be used as the
glucose sensor in the pancreas



GLUT 3—it is a high affinity system that is a major transporter in the CNS
GLUT 4—it is an insulin sensitive transporter; GLUT 4 transporters increase on the
cell surface in the presence of insulin
GLUT 5—it is a fructose transporter
38. Secondary active transport…
a. establishes an ion gradient to be used by the cell for transport processes.
b. includes uniport, symport and antiport mechanisms.
c. uses a pre-established ion gradient to drive the active transport of a second substance.
d. uses a pre-established ion gradient to drive the facilitated transport of a second substance
in the direction of its concentration gradient.
e. is like simple diffusion, but it requires an energy source.
A: C
LECTURE 18/20
1. What is a mechanism cells use for communicating extracellular events to intracellular processes?
A: Chemical signals
2. What is a hormone?
A: A substance that is produced in one tissue or organ that is released into the blood and
carried to another tissue or organ where it acts to produce a specific response.
3. What are some examples of hormones?
A: Amino acids and/or their derivatives, peptides, glycoproteins, cholesterol derivatives,
and fat-derived molecules
4. How does signal transduction work?
A: External chemical signals are received by receptors on the outside face of plasma
membranethe receptors produce chemical signals on the inside of the cellsthese
chemical signals propagate through the cell where they elicit specific cellular responses.
Some chemical signals enter the cell directly and bind to an intracellular receptor, which has
direct effects on cell processes
5. What are the two major classes of receptors?
A: Extracellular and intracellular
6. What do intracellular receptors typically bind and how do they typically act?
A: Typically bind steroid hormones, mineralocorticoids, retinoic acid derivatives, and
thyroid hormones. They almost always act at the DNA level, altering transcription of genes.
7. What do extracellular receptors typically bind and how do they typically act?
A: Typically bind peptide/protein hormones and tyrosine-derived catecholamines. They
almost always act to stimulate a signal cascade that affects many cellular proteins
8. What are the basic steps in cell signaling?
A:
 Recognition of the hormone signal
 Transduction of the signal across the membrane
 Transmission to intracellular components
 Modulation of the effector (2nd messengers produced)
 Response of the cell to the signal

Termination of the signal (degradation of 2 nd messenger)
9. What are the three types of signaling? Describe each.
A: Endocrine—source of hormone and target of hormone are far apart; paracrine—source of
hormone and target of hormone are adjacent; autocrine—cells produce and receives its own
signals
10. What are the five basic types of receptors?
A:
 Ligand-gated ion channels
 G-protein coupled receptors
 Catalytic receptors
 Intracellular (steroid) receptors
 Transmembrane proteins that release transcription factors
11. What are the three types of plasma membrane receptors?
A: Ion channel receptors, receptors that are kinases or bind kinases, and heptihelical
receptors
12. What type of receptor is the acetylcholine receptor?
A: Ligand-gated ion channel
13. How does the Ach receptor function?
A: Ach binds to the AchR stimulating a conformational change in the receptorthis opens a
channel allowing K+ and Na+ ions to flow changing membrane polarizationAch is
terminated by acetylcholinesterase
14. Which of the following operates by paracrine signaling?
a. glucagon
b. insulin
c. epinephrine
d. cortisol
e. acetylcholine
A: E
15. What type of receptor is the glucagon receptor?
A: It is a heptihelical, G-protein coupled receptor
16. What is the function of glucagon?
A: It is a hormone that signals the fasting state. It tells cells to turn on pathways that convert
energy stores to usable fuels, and turns off pathways the build up energy stores.
17. How does the glucagon receptor function?
A: Glucagon binds to glucagon receptor on cell surfaceconformational change induced in
receptorGDP exchange for GTP stimulatedactivation of alpha subunit of G-protein with
release of beta-gamma complexActivate alpha subunit binds to adenylate cyclasethis
activates adenylate cyclase, which begins producing cAMPcAMP activates protein kinase A
(PKA), which phosphorylates specific target enzymes of fuel metabolic
pathwaysphosphorylated fuel utilization enzymes get turned on, activity increasesafter
period of time, signal is quenched by cAMP phosphodiesterase degradation of cAMP
18. Signal cascades generated by G-protein coupled receptors are terminated when
a. the second messenger molecules are degraded.
b. the hormone dissociates from the receptor.
c. target molecules are dephosphorylated.
d. the G protein returns to the GDP-bound form.
e. All of the above.
A: E
19. What affect does cAMP have on gene transcription?
A: cAMP response element binding protein (CREB) binds cAMP binding protein (CBP),
which forms complexes at cAMP response element (CRE) and initiates gene transcription
20. What are the 5 types of G-alpha subunits? Function?
A:
 Gs: stimulatory—activates adenyl cyclase, increases cAMP, also activates Ca 2+
channels
 Gi: inhibitory—inhibits adenyl cyclase, prevents cAMP production, also activates K+
channels
 GO: Inhibits Ca2+ channels, depresses nerve activity
 Gq: activates phospholipase C, which produces IP3 and increases cell Ca2+ and
produces DAG, which activates PKC
 G12/13: cytoskeletal remodeling, smooth muscle contractions
21. Gαs can activate PLC or PLD. What are PLC and PLD functions?
A: PLC convert phosphotydylcholine (PC) to phosphocholine and DAG; PLD convert PC to
choline and phosphatidic acid (PA)
22. What are chemical messengers that work through PLC?
A: TNF-α, IL-1, IL-3, colony stimulating factor
23. Gq acts through PLC to do what? How?
A: Increase cell Ca2+; breaking down of PI 4,5-bisphosphate to IP3 and DAG
24. Receptor kinases consist of two subunits that are…heterodimers or homodimers?
A: Both
25. What stimulates association of the two subunits? What results from this?
A: Hormone binding; activation of the receptorphosphorylation of receptor
26. What are the two ways receptor kinases can be phosphorylated? Give example.
A: Autophosphorylation—subunits of tyrosine kinase receptors cross-phosphorylate each
subunit. Phosphorylated by a kinase that binds—JAK molecule is a tyrosine kinase domain
27. The phosphorylated site become what?
A: They become docking sites for adaptor proteins (STAT signal transducer protein of JAKSTAT receptor), which leads to activation of the adaptor protein.
28. What do the adaptor proteins do once activated?
A: They leave the receptor and bind cellular targets to change cellular state
29. Describe the general process of insulin receptor action.
A: Insulin binds to the alpha subunits of the insulin receptorAutophosphorylation of
receptorPhosphorylated receptor binds the insulin receptor substrate (IRS)IRS is
phosphorylatedphosphorylated IRS activates target proteins Grb2, PLCγ, and PI 3-kinase
30. Which enzyme cleaves PIP2 (also called PI-4,5-bisP) to IP3 and DAG to start the IP3 signal
cascade?
a. Phospholipase A1
b. Phospholipase A2
c. Phospholipase B
d. Phospholipase C
e. Phospholipase D
A: D
31. The insulin receptor substrate (IRS) is
a. phosphorylated by the insulin receptor, which activates it for binding a variety of other
protein targets.
b. binds insulin then activates the insulin receptor’s autophosphorylation activity.
c. an insulin molecule that binds the intracellular face of the receptor.
d. a kinase receptor.
e. is activated at all times, but is held in place on the receptor until insulin binds.
A: A
32. What role does PI 3-kinase, from insulin receptor activation, play in the formation of PI-3,4,5trisP?
A: PI-4,5-bisP is phosphorylated by PI 3-kinase, which forms PI-3,4,5-trisP.
33. What is the function of PI-3,4,5-trisP in insulin signaling?
A: PI-3,4,5-trisP binds and activates PDK-1 and PKB. PKB enters the cell cytoplasm,
propagating the insulin signal
34. What role does PLCγ, from insulin receptor activation, play in the formation of IP3 and DAG?
A: PI-4,5-bisP is cleaved by PLCγ into IP3 and DAG.
35. What is the function of IP3 and DAG?
A: IP3 binds to the IP3 receptor on the ER membrane which opens Ca2+ channels and
allows for flow of Ca2+ into cytoplasm. DAG can stimulate PKC, which leads to the
production of IP3. It often contains arachadonic acid at C-2, which can be cleaved by DAG
lipase to liberate free arachadonate…stimulating the eicosanoid pathways
36. What kind of process is the turning on/off gene transcription factors?
A: Receptor mediated process
37. What is the function of insulin?
A: Stimulates fuel storage and cellular growth and development
38. What is transactivation?
A: ligand induced conformation change of the receptor that results in its binding to a specific
segment of DNA to initiate transcription
39. What are the specific segments of DNA in transactivation called?
A: Response elements
40. What is the hormone response element?
A: It is a specific place on DNA that a steroid/thyroid hormone binds
41. What is the disease process in vibrio cholerae?
A: The toxin is constantly turning on adenylate cyclase, which leads to continuous
production of cAMP. This leads to increased fluid loss (diarrhea)
42. What is the disease process in bordetella pertussis?
A: ADP ribosylation of Gαi leads to the inability to exchange its bound GDP for GTP. This
means it cannot inactivate adenylate cyclase so there is a build up of cAMP.
LECTURE 19
1. How many essential vitamins and minerals play key roles in metabolism?
A: 28
2. What are vitamins?
A: Organic compounds that are natural components of food and are present in very small
amounts. They are essential because they cant be synthesized by us or synthesized in large
enough quantity to meet our needs
3. What gave birth to the field of nutrition?
A: The discovery of vitamins
4. What criteria do vitamins usually fall under?
A:
 Organic compounds distinct from fats, carbs, or protein
 Natural components of foods
 Not synthesized by the body in amount to meet physiological needs
 Essential for normal physiologic function
 Cause a specific deficiency syndrome by their absence of insufficiency
5. What are the two groups of vitamins?
A: Fat-soluble; water soluble
6. In what ways are vitamins destroyed?
A: With heat (cooking), light exposure (transport), acids (vinegar), metals, etc.
7. What are the fat-soluble vitamins?
A: A, D, E, K
8. What are the water-soluble vitamins?
A: C, thiamin, riboflavin, niacin, B6, biotin, pantothenic acid, folate, B12
9. What vitamins are dual-classified as hormones?
A: A and D
10. What does fat-soluble vitamins absorption depend on?
A: Micellar dispersion in the intestinal lumen (and bile salts)
11. How are fat-soluble vitamins generally excreted?
A: In enterohepatic circulation
12. What vitamin can be stored for up to 2 years in the adipose tissue?
A: Vitamin A
13. Give Vitamin A forms and functions, source, toxicity, and deficiency information.
A:

11-cis-retinol—part of visual cycle, visual pigment; Retinoic acid—growth
reproduction and maintenance of epithelial tissue; Beta-carotene—precursor of
vitamin A, antioxidant
 Found in animals; beta carotenes 600+ compounds found in plant foods
 Carotenoids store in adipose tissue give “orange skin”
 #1 vitamin deficiency in the world; leads to night blindness (xeropthalmia), Bitot’s
spots, corneal keratinization, poor wound healing, dry skin, infection susceptibility
14. Give Vitamin D functions, forms/source, toxicity, and deficiency information.
A:
 Functions to stimulate osteoclast activity with PTH, bone demineralization, assist
with calcium absorption in kidney and small intestine
 D2 (ergocalciferol) in milk—absorbed by SI; D3 (cholcalciferol) synthesized in skin
with UV light; 25-hydroxy D3—in liver, storage form; 1,25-dihydroxy D3 in kidney,
active form
 Can lead to bone demineralization, hypercalcemia, and kidney stones
 Deficient children—rickets, skeletal deformation, short stature, “pigeon breast”;
Deficient adults—osteomalacia, general bone pain, liver disease, chronic renal
failure
15. Give Vitamin E forms and functions, source, and deficiency information.
A:
 8 forms, most biologically active is alpha-tocopherol
 nuts and seeds
 functions as antioxidant, maintains cell membrane integrity, protects unsaturated
phospholipids of the membrane from oxidative degradation from free radicals and
highly reactive oxygen species (ROS)
 Being deficient can lead to fragile membranes, poor vision, neuro dysfunction,
myopathy
16. Give Vitamin K source, functions, and deficiency information.
A:
 Green leafy veggies and intestinal microbe synthesis
 Clotting factors, cofactor for glutamate carboxylase
 Being deficient can lead to poor clotting, bruising, mucus membrane bleeding,
prolonged PT/PTT, recent use of broad spectrum Abs
17. What do water-soluble vitamins function primarily as?
A: Cofactors and coenzymes in energy metabolism
18. What is the name for B1? Where is it used? What happens if deficient?
A: Thiamin; PDHase and transketolase; dry, wet beriberi, Wenicke-Koraskoff, amnesia
19. What is Wenicke-Koraskoff?
A: Wernicke encephalopathy causes brain damage in lower parts of the brain called the
thalamus and hypothalamus. Korsakoff psychosis results from permanent damage to areas
of the brain involved with memory
20. What is the name for B2? Where is it used? What happens if deficient?
A: Riboflavin; in FAD and FMN; angular chelitis, corneal vascularization
21. What is the name for B3? Where is it used? What happens if deficient?
A: Niacin; NAD and NADH; no appetite, weakness, dermatitis, dementia, diarrhea, death
22. What is the name for B5? Where is it used? What happens if deficient?
A: Pantothenic acid; in Co-ASH; hair loss, gastritis
23. What is the name for B6? Where is it used? What happens if deficient?
A: Pyridoxal; AA synthesis; pregnancy or isoniazid, oral contraceptives, neuropathy seizures
24. What is the name for B7? Where is it used? What happens if deficient?
A: Biotin; cofactor for carboxylation reactions in gluconeogenesis, FA synthesis, and
metabolism; dermatitis, gastroenteritis, elevated cholesterol
25. What is the name for B9? Where is it used? What happens if deficient?
A: Folic acid; required for methyl transfers; spina bifida, neural tube defects
26. What is the name for B12? Where is it used? What happens if deficient?
A: Cobalamin; assist in change of homocysteine to methionine; pernicious anemia
27. What is Vitamin C function? What is result of deficiency? What is result of excess?
A: Serves as biochemical redox system involved in electron transport systems; scurvy; GI
disturbances, diarrhea, oxalate kidney stones
28. Low RBC transketolase activity leads to what?
A: Wernicke’s encephalopathy (B1 deficient)
29. B12 deficiency can result from what?
A: Strict vegan diet with megaloblastic anemia
30. PDH enzyme complex use what vitamins?
A: thiamin (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6), lipoic
acid
31. What are minerals?
A: a group of inorganic nutrients, which largely are considered essential that we need in
very small amounts
32. Minerals are typically absorbed by what cells?
A: Intestinal cells
33. What is bioavailability?
A: The absorption and utilization of the elements in both tissue and cellular functions
34. What are the classifications of minerals?
A: Electrolytes, minerals, trace minerals, ultra trace minerals
35. What are electrolytes? What is their function?
A: Na+, K+, and Cl-; establish ion gradients across cell membranes and maintain our water
balance
36. What is the importance of the minerals calcium and phosphorus?
A: skeletal structure, blood clotting, and hormones; energy production
37. What is the importance of the mineral iron?
A: Major component of hemoglobin
38. What is the importance of the mineral sulfur?
A: Found in connective tissue and plays role in metabolism
39. How many servings of fresh fruits and veggies should we consume daily?
A: 5-9
40. What are the “major minerals”?
A: Calcium, phosphorus, magnesium, sodium, chloride, and potassium
41. What are the “selected micro-minerals”?
A: Iron, Zinc, Copper, Iodine, and Selenium
42. What two “micro-minerals” are the major mineral deficiency in the world?
A: Iron and Iodine
43. What is Kwashiorkor a result of?
A: Protein deficiency
44. What is Marasmus a result of?
A: Energy deficiency
45. What is Zinc function? What results from deficiency?
A: cofactor for collagenase (wound remodeling) and in children—spermatogenesis and
growth; delay in wound healing, decrease in adult hair, hypogonadism, loss of taste and
smell
46. What is Copper function? What results from deficiency?
A: cofactor for ferroxidase, attaches iron to transferrin for lysyl oxidase, cross-linkages in
collagen and elastic tissue for tyrosinase, converts tyrosine to melanin; microcytic anemia,
aortic dissection, poor healing, Wilson’s Disease, poor elimination of Cu into bile
47. What is Selenium function? What results from deficiency?
A: cofactor for glutathione peroxidase (antioxidant role), converts peroxide to water;
weakness and muscle pain, dilated cardiomyopathy
48. What is iodine function?
A: Structural role in hormones regulating basal metabolic rates
49. What impacts health status and recommendations?
A: Bioavailability and absorption
50. How much calcium do we typically absorb from food?
A: 50%
51. How much iron is absorbed from red meat? Plant sources (spinach)?
A: 20%; 5-10%
52. Absorption requires transport proteins in which cell membranes of the small intestine?
A: duodenal
53. What other minerals compete for absorption?
A: Zn, Ca, Mn, Cu, Ni, Pb
54. What are ways you can assess Vit A in patients?
A:
 Clinical, functional/physical, histological, biochemical
 Visual acuity
 Electroretinogram
55. What are the ways vitamin A is excreted?
A: As water-soluble metabolites in urine, feces via bile, and some expired with CO2;
Carotenoids are either converted to retinoids or excreted in bile
56. How can you assess Fe?
A: Hb/Hct; TIBC, ferritin level
57. What does ABCD(E) stand for?
A:
 Anthropometric—bone density
 Biochemical—blood, urine, feces, hair, nails
 Clinical—physical exam
 Dietary—food content and patient intake
 Education/Economic/Emotional
58. What does DRI stand for? EAR? RDA? UL? AI? DV?
A:
 DRI—Dietary reference intakes
 EAR—Estimated average requirement
 RDA—recommended dietary allowance
 UL—upper limit
 AI—Adequate intake
 DV—daily value
59. Women need at least how many servings of calcium-rich foods a day?
A: 3
60. What are some calcium serving equivalents?
A:
 1 cup low-fat or fat-free milk
 1 cup low-fat or fat-free yogurt
 1 ounce low-fat or fat-free cheese
 1 ½ cups cooked edamame
 1 cup calcium-fortified juice
61. What act was put in place to amend the Federal Food, Drug, and Cosmetic Act to establish
standards with respect to dietary supplements, and for other purposes?
A: Dietary Supplement Health And Education Act of 1994
62. What percent of adolescent boys and girls eat the recommended servings of dairy foods?
A: <50% of boys; 1/5 of girls
63. What is the goal dietary ratio for Ca:P intake? What is the current US diet ratio?
A: 2:1 or at least 1:1; 1:2
64. GO BACK AND LOOK AT CHARTS ON SLIDES 23 and 29!!!!!! KNOW THEM!
LECTURE 20/21
1. What is metabolism?
A: The sum of all the enzyme-catalyzed reactions that occur in a living organism. It is a
dynamic, coordinated, and highly regulated activity.
2. What are metabolites?
A: Small molecules involved in the synthesis and degradation of biopolymers and the interconversion of chemical compounds
3. What is the central intermediate in most ATP production pathways?
A: Two carbon acetyl group (Acetyl CoA)
4. What are the two metabolic pathways?
A: Catabolism and Anabolism
5. What is catabolism?
A: The breakdown of biomolecules to produce energy and the building blocks for other
synthesis. Fuels are oxidized completely to CO2 and H2O
6. Where do catabolic pathways products eventually enter in metabolism?
A: The TCA cycle
7. The energy released by catabolism is conserved in three types of molecules. What are the three
types of molecules?
A: Nucleoside triphosphates (ATP, GTP), reduced coenzymes (NADH, NADPH, FADH2,
FMNH2), and acetyl CoA
8. What is anabolism?
A: The biosynthesis of more complex molecules from small precursors in reductive (uses
energy) pathways. Anabolic pathways are divergent starting with a few metabolites and
producing many different molecules.
9. What is the difference in aerobic and anaerobic metabolism?
A: Aerobic requires oxygen for ATP production; Anaerobic does not require oxygen for ATP
production
10. What is a metabolic pathway?
A: A series of coupled reactions in which the product of one reaction acts as the substrate of
the next reaction with regulation of the flow metabolites
11. What is an amphibolic pathway?
A: A pathway involved in both anabolic and catabolic processes
12. What is the function of the substrate cycle?
A: It controls the degradative and synthetic pathways for biomolecules that use the same
pathway. They prevent futile cycling.
13. What does it mean for the substrate cycle enzymes to be reciprocally regulated?
A: When one set of enzymes are “on”, the other set of enzymes is “off.”
14. What is futile cycling?
A: Burning up of precious energy reserves in cyclical reactions.
15. What two pathways were provided as example of substrate cycles? How do the two function?
A: Glycolysis uses glucose to produce ATP and Gluconeogenesis produces glucose
16. How does compartmentalization of metabolic pathways help regulate efficient use of metabolic
pathways?
A: They are compartmentalized within cells by restricting pathways to particular subcellular
organelles and by specialization of tissues.
17. What organ is the central site of intermediary metabolism?
A: Liver
18. What are the dietary fuels and give examples?
A: Carbohydrates—starch, sucrose, lactose, fructose, glucose; Proteins—any polypeptide
composed of amino acids; Fats—triacylglycerides, fatty acids, lipids; Alcohol—ethanol in
various forms
19. What forms of carbohydrates are essential to the diet? Why?
A: None. We can synthesize any carbohydrate needed
20. What are essential fats to the diet? Where do they come from? What do they do?
A: Linoleic acid and a-linoleic acid; dietary plant oils; linoleic acid is used to make
arachidonic acid, which is needed for hormone (eicosanoid) synthesis. a-linoleic acid is used
to make EPA, which is needed to produce DHA
21. What are the essential amino acids to the diet?
A: Threonine, Isoleucine, Leucine, Tryptophan, Methionine, Valine, Phenylalanine, Histidine,
Lysine
22. Where are fuels stored?
A: Fats—stored as triacylglycerides in adipose tissue; Carbohydrates—converted to glucose
and stored as glycogen in liver and muscles; Amino acids—stored in muscles
23. Describe the process of energy balance.
A: Consume more food, store more fuel and gain more weight. Consume less food, use fuel
storage and lose weight.
24. What is BMR?
A: Basal Metabolic Rate—the energy required to sustain life
25. What is DIT?
A: Diet Induced Thermogenesis—metabolic rate increases after consuming a meal due to
energy required to digest, absorb, distribute, and store fuels
26. What is BMI?
A: Body Mass Index—the method for determining whether a persons weight is in the
healthy range.
27. What is the fed state?
A: It means that the fuels we consume are oxidized and made available to meet our
immediate energy needs. The excess fuel is stored as triacylglycerol and glycogen
28. What locations do the enzymes of digestion/absorption break down food into its smallest units?
A: Mouth, Stomach, and Small intestine
29. What are complex carbohydrates broken down into?
A: Monosaccharides
30. What are proteins broken down into?
A: Amino acids
31. What happens to fats in digestion?
A: They are emulsified in the intestine by bile salts and form microdroplets called
chylomicrons
32. Where does most initial processing of nutrients occur? How does it get there?
A: Liver; Portal vein transport
33. What is the insulin/glucose process after a meal?
A: Glucose in the blood stimulates production of insulin by the pancreasinsulin stimulates
cells to take up glucoseinsulin signals cells to grow, build, and store excess fuelsinsulin
causes glucagon levels to decrease
34. What are some major organs/areas glucose goes after digestion? What is its function there?
A:
 Liver—immediately metabolized for ATP and remainder is converted to glycogen
and triacylglycerol
 Brain and nervous system—major energy source
 RBCs—only energy source
 Muscle—energy and maintain glycogen stores in muscle
 Adipose tissue—energy and provides glycerol moiety for making TGs for storage
35. What is the fate of lipoproteins in the fed state?
A: Chylomicrons transport TG and cholesterol from the intestines to the tissues. VLDLs
transport TG in the blood to adipose and peripheral tissues
36. Chylomicrons give what a first chance at utilizing fat?
A: Muscle
37. Where/How are VLDLs formed?
A: in the liver following fat and TG synthesis
38. What is the fate of amino acids in the fed state?
A: Most are used to synthesize new proteins, but some are oxidized to yield energy or used
to make important metabolites
39. What part of the body is a major user of amino acids to make new protein?
A: Muscle
40. What occurs in the fasted state?
A: The body utilizes fuel stores to provide energy for tissues, especially the brain
41. How/where does the body store fat, proteins, and carbohydrates?
A: Fat is stored in adipose tissue as triglycerides; Protein is stored in skeletal muscles and
can provide amino acids on a short term basis; Carbohydrate is stored in the liver, muscle,
and other cells as glucose or glycogen
42. When do blood glucose levels peak after eating?
A: 1 hour
43. How quickly after eating a meal is the body back in the fasting state?
A: 2 hours
44. What is the role of glucose and the liver during fasting?
A: Decreased blood glucose levels signal the pancreas to stop producing insulin. The liver
responds to decreased insulin levels by degrading glycogen and releasing glucose into the
blood stream.
45. What is the body state like 12 hours after eating?
A:
 Serum insulin levels are low
 Glycogen stores are decreasing because the liver needs to maintain blood glucose
levels
 Glucagon:insulin is high
 Gluconeogenesis is starting to supply glucose
 FA oxidized directly to yield energy in many tissues to preserve glucose
46. What is a major problem that occurs 12 hours after eating?
A: Most fatty acids can’t provide carbon for gluconeogenesis, only the glycerol part of TG can
be used as a starting material
47. What is the role of adipose tissue in fasting?
A: FA from TG provide the major source of fuel. FA oxidized to acetyl CoA leading to lots of
ATP production. Glycerol backbone of TG is used for gluconeogenesis. In the liver, most FA
taken up are used to produce ketone bodies (KB), which are used by some tissues for energy
48. What are the metabolic changes during a short fast?
A:
 The liver maintains blood glucose levels
 FAs from adipocytes provide major source of energy
 KB are important source of energy
 Brain relies on blood glucose
 Nitrogen, produced as byproduct of using AA in gluconeogenesis, is converted to
urea
49. What are the metabolic changes during a long fast?
A:
 Emphasis shifts away from producing glucose as the major fuel
 Muscle decreases use of KB and uses FA oxidation as source of fuel
 Brain starts to take up and utilize KB to make acetyl CoA
 AAs only used for gluconeogenesis to provide glucose to RBCs
 Decreased AA being used leads to less urea production
50. What is the role of adipose tissue during a long fast?
A: Provide TGs, so glycerol can be used for gluconeogenesis and FA oxidation can drive KB
production in the liver
51. What determines the length we can fast?
A: Amount of adipose tissue available
LECTURE 23
1. What is thermodynamics?
A: A collection of laws and principles describing the flows and interchanges of heat, energy,
and matter in systems if interest
2. What is enthalpy (H)?
A: H is a function related to heat transfer and work expenditure in the system
3. What is ΔH?
A: It refers to the change in enthalpy that occurs during a reaction or change in state
4. What does a negative ΔH imply? Unfavorable or favorable?
A: Heat is lost by the system; favorable
5. What does a positive ΔH imply? Unfavorable or favorable?
A: Heat is gained by the system; unfavorable
6. Describe H in protein folding and unfolding.
A: In protein folding, weak interactions are formed and energy is liberated making it a
favorable reaction (-ΔG). In protein unfolding, the weak interactions are broken, which
requires energy making it unfavorable (+ΔG).
7. What is entropy (S)?
A: A measure of disorder/randomness
8. An ordered state has … entropy. A disordered state has … entropy. ______ in entropy is always
favored.
A: low; high; increase
9. What does a negative ΔS imply? Unfavorable or favorable?
A: The system has become more ordered; unfavorable
10. What does a positive ΔS imply? Unfavorable or favorable?
A: The system has become less ordered; favorable
11. Describe S in interaction of water with a polar solute and a non-polar solute.
A: Interaction of water with a polar solute (NaCl) leads to more disorder and high entropy.
Interaction of water with a non-polar solute (oil) leads to more order and low entropy.
12. What is free energy?
A: Tells how much energy is available for work and allows one to assess reaction
spontaneity.
13. What is the free energy equation?
A: G = H – T*S or ΔG = ΔH - TΔS
14. What does a negative ΔG imply? Unfavorable or favorable? Related to the equation, what leads
to negative ΔG?
A: the system has decreased in free energy; favorable; negative ΔH, large positive ΔS or both
15. What does a positive ΔG imply? Unfavorable or favorable? Related to the equation, what leads to
positive ΔG?
A: the system has increased in free energy; unfavorable; positive or large ΔH, negative or
small ΔS
16. What is occurring if ΔG=0? ΔG<0? ΔG>0?
A: Reaction is at equilibrium; Reaction proceeds to product formation (spontaneous);
Reaction proceeds in reverse for reactant formation (non-spontaneous)
17. Considering the equation A + B C + D, what is Keq?
A: [C][D]/[A][B]
18. What is the standard free energy change at equilibrium?
A: ΔG0 = - RT lnKeq
19. What is the relationship between Keq and ΔG0?
A: If Keq < 1, lnKeq is negative and ΔG0 is positive (non-spontaneous); If Keq > 1, lnKeq is
positive and ΔG0 is negative (spontaneous)
20. Many reactions in cells must run (with/against) the thermodynamic potential?
A: against
21. What reactions do cells couple together to make them proceed?
A: Highly favorable reactions (large, negative ΔG0) and energy-requiring reactions (positive
ΔG0)
22. What are high-energy biomolecules?
A: They are “energy shuttles” that move energy around to reaction sites where it is needed
and used to drive the energetically unfavorable reactions.
23. What are the two classes of biomolecules that do energy transfer? Provide examples.
A: Reduced coenzymes—NADH, FADH2; High-energy phosphate compounds—ATP, GTP
24. List in order from high energy to low energy and provide the ΔG0: PEP, ATP, Glucose 6-P, 1,3BPG, UDP-Glucose, Acetyl CoA.
A: PEP (-62.2)> 1,3-BPG (-49.6)> ATP (-35.7)> UDP-Glucose (-31.9)> Acetly CoA (-31.5)>
Glucose 6-P (-13.9)
25. What is the energy currency of the cell?
A: ATP
26. How is ATP energy transferred?
A: Through the phosphate bonds
27. What are two phosphoric-carboxylic anhydrides? Are they energy rich or energy poor? What is
responsible for this?
A: Acetyl-phosphate and 1,3 BPG; very energy rich; bond strain, electrostatics, and
resonance
28. Why is ATP considered a transient energy carrier?
A: It quickly passes its energy to a host of energy-requiring processes
29. What molecule has the largest free energy of hydrolysis of any biomolecule?
A: Phosphoenolpyruvate (PEP)
30. Formation of what is one of the central goals of many metabolic pathways?
A: PEP
31. What kind of process is energy transfer?
A: Coupled
32. Describe the coupled process between UTP and Glucose 1-P.
A: UTP can transfer energy to G-1-P by coupling to UDP to G-1-PEnergy of diphosphate
bond belongs to UDP-GlucoseUDP-Glucose reacts with glycogen to store G-1-P molecules
33. What are the two electron shuttles? How many H+ do they carry? e- do they carry?
A: FADH2—2H+, 2 e-; NADH 1H+, 2 e34. Do the electron shuttles carry potential energy or electron energy?
A: Electron energy
35. In what terms does fuel oxidation provide energy?
A: Reducing equivalents (electrons, e-)
36. In order to use the energy of e-, e- are transferred from NADH/FADH2 to what?
A: The electron transport chain
37. How is energy transformed in the body?
A: By the transfer of electrons and hydrogen from fuel to electron-accepting coenzymes
38. The ETC is terminated by what?
A: Donating the electrons to the molecular oxygen forming water
39. What is the end product of fuel oxidation?
A: CO2 production
40. List the redox cofactors (8).
A:
 NAD+/NADH
 NADP+/NADPH
 FAD/FADH2
 FMN/FMNH2
 Coenzyme Q
 Lipoic acid
 Vitamin C
 Tetrahydrobiopterin
41. Describe how the oxidation-reduction reaction occurs.
A: An electron donor (reducing agent) transfers electron(s) to an electron acceptor
(oxidizing agent).
42. What is the redox potential (E0’)?
A: The tendency of electrons to be transferred from one biological molecule to another.
43. Describe electron flow in regards to redox potential.
A: Electrons flow spontaneously from a molecule with a more negative to a molecule with a
more positive E0’.
LECTURE 24
1. How many grams glucose/day are required for most adults?
A: 190
2. What are the two strategies for homeostasis?
A: Local control and hormonal control
3. What is local control?
A: Concentration of metabolites in the blood or cells affects enzyme activites
4. What is hormonal control?
A: Hormones carry messages to individual tissues about the state of the body and supply of
fuel or demand of nutrients
5. What are the primary metabolic hormones?
A: Insulin and glucagon
6. What organ are insulin and glucagon synthesized and released from? What specific cells produce
each?
A: Islets of Langerhans on the pancreas; β cells—insulin; α cells—glucagon
7. What does it mean to be counter regulatory?
A: The effect of each hormone counteracts the effects of the other hormone
8. Which hormone is the anabolic hormone that signals the fed state?
A: Insulin
9. In what ways does insulin promote storage of fuels or utilization of fuels for growth?
A:
 Glucose storage as glycogen in liver and muscle
 Conversion of glucose to TG in liver and storage in adipose tissue
 Amino acid uptake and protein synthesis in skeletal muscle
 Increases synthesis proteins required for fatty acid transport and storage
 Inhibits fuel mobilization
10. What is the release of insulin dictated by?
A: Blood glucose levels
11. How long after a meal do insulin levels peak? Return to basal level?
A: 30-45 minutes; 2 hours
12. Does low glucose levels stimulate insulin release? Why or why not?
A: No, because pancreatic β-cells have glucokinase, which has a low affinity for glucose
13. How does insulin get into the blood?
A: β-cells secrete insulin into the hepatic portal vein via the pancreatic vein
14. How does epinephrine affect insulin?
A: It decreases the release of insulin
15. How does insulin affect cells?
A: it can have growth factor like effects or phosphorylation/dephosphorylation cascades for
metabolism
16. What hormone is the catabolic hormone of the body, which signals the fasted state?
A: Glucagon
17. How does glucagon promote fuel utilization?
A:
 Release of glucose from liver glycogen
 Gluconeogenesis from lactate, glycerol and amino acids
 Mobilizes fatty acids out of adipose tissue
18. What does glucagon release depend on?
A: the absence of glucose and insulin
19. Describe the relationship between the levels of insulin and glucagon.
A: Glucagon levels increase as insulin levels fall, vice-versa
20. What is the half-life of glucagon?
A: 3-5 minutes
21. Glucagon levels will remain high after what kind of meal?
A: High protein
22. Describe the difference in levels of glucagon and insulin in regards to high protein meals vs. high
carb meals.
A: Prior to a high carb meal, glucagon levels will be high. After eating a high carb meal,
insulin levels will rise to signal the uptake and storage of glucose, glucagon levels will fall. In
a high protein meal, glucose and insulin levels will be low and glucagon levels will be high to
maintain blood glucose levels
23. What are the two major effects PKA has on glycogen?
A: Glycogen synthesis stops and glycogen degradation begins
24. Amplification of what molecule leads to rapid mobilization of glycogen degradation?
A: cAMP
25. What leads to the termination of glycogen degradation?
A: Dephosphorylation of phosphorylase kinase
26. Describe how phosphorylation affects glucagon/insulin relationship.
A: Glucagonphosphorylationturns off glycogen synthesis, turns on glycogen breakdown
Insulindephosphorylationturns on glycogen synthesis, turns off glycogen breakdown
27. What are some other pathways that are counter regulatory?
A:
 FA oxidation vs. FA synthesis
 FA mobilization from adipose vs. FA storage into adipose
 Amino acid utilization vs. amino acid synthesis
28. What are some other hormones that affect glucose homeostasis?
A: Epinephrine, norepinephrine, and cortisol
29. Release of the hormones is mediated by what?
A: neuronal signals (fear, low blood glucose, fatigue, etc.)
30. What hormone is the “fight or flight” hormone?
A: Epinephrine
31. How does epinephrine assist in glucose homeostasis?
A: Binds to β receptorsstimulates adenylate cyclasecAMP productionPKA
activationsignals urgent need for more glucose
32. What receptors do epinephrine bind to in the liver?
A: α receptors
LECTURE 25/26
1. Most catabolic pathways oxidize fuel sources into what for the TCA?
A: Acetyl CoA
2. The TCA cycle is the hub for anaerobic metabolism responsible for oxidation of what?
A: acetyl CoA into CO2 and H2O
3. What is the TCA cycle function?
A: To oxidize acetyl CoA by removing two electrons from the acetyl group and transferring
them to NAD+ and FAD
4. What is the goal of the TCA cycle?
A: To conserve the energy of acetyl CoA oxidation in the form of electron transfer from a
series of carbon compounds to form NADH and FADH2
5. What percent of the energy produced by the TCA cycle is conserved?
A: 90%
6. What is the fate of the reduced coenzymes?
A: They are reoxidized by the ETC in mitochondria with the production of ATP by oxidative
phosphorylation
7. What is the outcome of the TCA cycle in respect to carbons, NADH, FADH2, GTP, and ATP.
A:
 No net synthesis of Carbons (2 in, 2 out)
 3 NADH
 1 FADH2
 1 GTP
 9 ATP
8. How does the TCA produce the 9 ATP?
A: Oxidative phosphorylation; 2.5 ATP/NADH and 1.5 ATP/FADH2
9. How many steps are there to the TCA cycle?
A: 8
10. The formation of citrate and isomerization to isocitrate takes how many steps of the TCA cycle?
A: Steps 1 and 2.
11. How does is citrate formed?
A: condensation reaction of oxaloacetate and acetyl group of acetyl CoA
12. What enzyme isomerizes citrate to isocitrate?
A: Aconitase
13. What occurs during Step 3 of the TCA?
A: the oxidative carboxylation of isocitrate forms α-ketogluterate. CO2 released and 2
protons released, while a double bond is formed
14. What occurs during Step 4 of the TCA?
A: CO2 is removed from the α carbon of α-ketogluterate, 2 electrons from bond are
transferred to NAD+ molecules, CoA forms a high energy bond with α-carbonsuccinyl coA
15. What step in the TCA is an example of a substrate level phosphorylation for the formation of a
high-energy triphosphate compound without the use of O2?
A: Step 5
16. What occurs in Step 5?
A: Succinyl CoA is broken down to succinate. The energy from the breaking of the succinyl
CoA thioester bond is used to generate GTP from GDP
17. What occurs in the last 3 steps of the TCA cycle?
A: Succinate is oxidized to fumarate FADH2 is formedwater adds across double bond of
fumarate forming malatedehydrogenation of malate results in oxaloacetate regeneration
and NADH formation
18. What enzyme is a component of the TCA cycle and the ETC?
A: Succinate dehydrogenase
19. What cofactors (10) are required in the TCA cycle?
A:
 TPP
 FAD
 FMN
 NAD+
 CoA
 Lipoate
 Iron
 Magnesium
 Sulfur
 Phosphorus
20. What three reactions of the TCA cycle are exothermic?
A: formation of citrate; formation of αKG; formation of succinyl CoA
21. Why are the reactions above virtually irreversible?
A:
 The reverse reaction is very slow
 The amount of product from each reaction is small because the products are used in
the subsequent reactions
22. What reactions of the TCA cycle are endothermic?
A: Citrate formation and malate formation
23. Where are intermediates of the TCA cycle used in other bodily processes? (citrate, αKG, SCoA,
malate, OAA)
A:
 Citrate—fatty acid synthesis
 αKG—amino acid synthesis/neurotransmitter
 SCoA—heme synthesis
 Malate—gluconeogenesis
 OAA—amino acid synthesis
24. What are anaplerotic reactions?
A: reactions that produce intermediates for the TCA cycle
25. What is the most important anaplerotic reaction?
A: pyruvate + CO2OAA by pyruvate carboxylase
26. What are the two key ratios that control the TCA cycle?
A: ATP/ADP and NADH/NAD+ ratio
27. What are some considerations (7) for the regulation of metabolic pathways?
A:
 Rate-limiting steps
 Committed steps
 Irreversible reactions
 Feedback inhibition
 Compartmentation
 Hormonal regulation
 Tissue-dependent controls
28. What is a primary link between Acetyl CoA multiple sources and fates?
A: Pyruvate dehydrogenase (PDH)
29. What are allosteric stimulators for active PDH?
A: Pyruvate, NAD+, and CoA
30. What are allosteric inhibitors of active PDH?
A: NADH and Acetyl CoA
31. In regards to metabolic state, what conditions favor phosphorylated PDH?
A: Fasting
32. Citrate synthase is stimulated by what two molecules?
A: acetyl CoA and OAA
33. Citrate is inhibited by what molecule?
A: Citrate (product inhibition)
34. What is ΔG0 for citrate synthase?
A: Large and negative
35. What is the rate-limiting step of TCA?
A: Isocitrate dehydrogenase
36. Isocitrate dehydrogenase is allosterically activated by what? Inhibited?
A: ADP and Ca2+; NADH
37. What makes isocitrate dehydrogenase show positive cooperativity?
A: No ADP
38. What effect does ADP have on isocitrate dehydrogenase?
A: It decreases cooperativity and greatly increases enzyme activity
39. What is a rate-limiting enzyme function?
A: It causes an accumulation of precursors, which leads to those accumulated precursors
going off to other pathways
40. What is ΔG0 for malate dehydrogenase?
A: Large and positive
41. What molecule affects malate dehydrogenase and how does it affect malate dehydrogenase?
A: NADH stops the conversion of malate to OAA, which causes malate to accumulate.
42. Where is this excess malate utilized?
A: It is utilized in the cytoplasm for gluconeogenesis
43. How does lactate dehydrogenase (LDH) function?
A: LDH is the interconversion of pyruvate and lactate using NAD+/NADH
44. LDH is dependent on what?
A: Tissues
45. What does LDH favor in the heart? In RBCs?
A: Pyruvate production from lactate; lactate production from pyruvate
46. RBCs lack what organelle that keep them from processing acetyl CoA?
A: Mitochondria
47. What happens to lactate after it is converted in the RBC?
A: It is eliminated from the cell into the blood and picked up by cells that use lactate (heart,
liver)
48. What is the difference between fast-twitch (white) skeletal and cardiac muscle/slow-twitch (red)
skeletal muscle use of pyruvate and lactate?
A: Skeletal muscle have very little mitochondria so once production of pyruvate exceeds the
mitochondrial capacity to utilize it, lactate is produced and eliminated. Cardiac
muscle/slow-twitch skeletal muscle contain a lot of mitochondria. These muscles take up
lactate and convert it to pyruvate for conversion to acetyl CoA for TCA cycle.
49. What must be present for LDH activity?
A: lactate and NAD+ OR pyruvate and NADH
50. How many substrates can the enzyme LDH hold?
A: 2 it is bisubstrate enzyme
51. How does LDH serve as a marker for RBC/tissue damage?
A: If RBC/tissue is damaged or lysed, LDH is released into the blood and LDH levels can be
measured.