Download Exam 1 SQ Key Chapter 2: Water and Carbon—The Chemical Basis

Exam 1 SQ Key
Chapter 2: Water and Carbon—The Chemical Basis of Life
Lecture 2 PPT Review:
1.) What is electronegativity? Compare and contrast polar covalent vs nonpolar covalent bonds?
a. Electronegativity = A measure of the ability of an atom to attract electrons toward
itself from an atom to which it is bonded (caused by number of protons in NUC and
distance between NUC and valence shell.
b. Nonpolar Covalent—electrons are shared equally between atoms of the same or
similar electronegativity
Polar Covalent—electrons are shared unequally between atoms differing in
electronegativity. This results in a the more electronegative atom having a partial
negative charge and the other atom having a partial positive charge
2.) Why do partial charges form on molecules?
^^^
3.) What is an ionic bond?
a. Electron is completely transferred from one atom to another so that the atoms remain
associated due to their opposite electric charges
4.) Explain the properties of water
a. Polar or Nonpolar?
i. Polar
b. Covalent or noncovalent bonding?
i. Covalent
c. Partial charges for each atom?
i. Partial negative on oxygen and partial positive on H’s
5.) What types of bonds form between water molecules?
a. Hydrogen bonds
6.) Why is water an excellent solvent? (p.25) –think about its interaction with an ionic molecule like
NaCl.
a. Electronegativity causing partial + and partial – charge
b. Molecule is bentPartial – charge of O sticks out, away from the partial + charges on
H. Makes it so these partial charges can interact with those on other H2O (H-bonding)
or other molecules.
i. Ions and polar molecules stay in solution bc of their interaction w/ H2O
charges
7.) Are nonpolar molecules hydrophilic or hydrophobic? What properties of both the molecule and
water cause this?
a. HydrophobicUncharged and nonpolar. They have minimal or nonexistent
interaction with water. H2O is opposite of this (Polar w/ the partial charges)
8.) What are the two properties of buffers we discussed?
1. Resist changes in pH
2. Have the ability to accept or donate H+
9.) What is pH? What is the physiological pH?
a. pH = the concentration of H+ (proton) in solution
b. Physiological pH = 6.5 – 8.0
10.) At a basic pH, what is the relationship between [OH-] and [H+]? What is the relationship at an
acidic pH?
a. Basic = [OH-] > [H+]
b. Acidic = [H+] > [OH-]
11.) What types of bonds can carbon form? How many?
a. Covalent bonds
b. 4 because Carbon has 4 electrons in outer valence shell so needs 4 more electrons to
complete octet. Therefore forms 4 covalent bonds to satisfy this.
12.) Be sure to know the functional groups and family of molecules that Dr. A recommended to
know!
13.) Review the examples on the PPT + Bioskills 6 and 8 in Appendix B of textbook.
Chapter 3: Protein Structure and Function
Lecture 3 “PSF” Review:
1.) What is an amino acid (AA)? What are the structural components of an AA? What is the central
carbon denoted as?
a. AA = the building blocks of proteins, each containing an amino group, a carboxylic
group, and a side chain (R group) attached to the alpha carbon
2.) What is the difference between the non-ionized form of an AA and the ionized form? (Be able to
draw both is a good idea!)
a. Ionized has carboxylic group deprotonated (COO-) and amino group protonated
(NH3+)
3.) Which structural component of an AA distinguishes it from all of the other AAs?
a. The side chain (R group)
4.) Classify the AAs according to the following properties of their side chains:
a. Nonpolar
i. G A P I L V M C F W
b. Polar
i. S T Y N Q
c. Polar (+) charge
i. H R K
d. Polar (-) charge
i. D E
5.) Which AAs are basic? Which are acidic?
a. Basic = H R K
b. Acidic = D E
6.) What is the name of the covalent bond that links peptides? What reaction joins peptides
together? What molecule is released during this reaction? What is the reverse of this reaction?
a. Peptide Bond
b. Condensation Rxn
c. H2O released
d. Hydrolysis
7.) Is the directionality of AA arranged CN terminus or NC terminus?
a. NC
8.) Describe the flexibility of the peptide backbone.
a. Peptide bond has partial double bond character which limits free rotationthe bonds
directly adjacent to the alpha carbon have some rotation
9.) Explain the four levels of protein structure.
a. 1* = sequence of amino acids
b. 2* = Hydrogen bonding between peptide backbone that form alpha helices and beta
sheets. H-bonding between C=O on one AA to the Hydrogen on N-H of another AA
c. 3* = Interactions between the R groups causes the protein to adopt its folded
structure. One of the driving forces here is the hydrophobic effect. Disulfide bridges
between Cys, van der waals, h-bonding (polar r groups), ionic.
d. 4* = Multiple polypeptides coming together to form a single structure. Can have
different functions. Defined by “domains” of the protein
10.) What are the structural differences between alpha helices and beta sheets?
11.) Are peptide bonds broken when proteins denature? What two ways (that we discussed) can a
protein be denatured?
a. Peptide bond stays intact
b. Heat and surface denaturation
Chapter 4: Nucleic Acids and the RNA World
Lecture 4 PPT Review:
1.) What are the structural components of nucleic acids? Nucleic acids are also called what type of
molecule?
a. 5-carbon sugar, nitrogenous base, and phosphate group
b. Nucleotide
2.) What structural feature distinguishes ribose from deoxyribose?
a. Ribose has OH on C2 while deoxyribose has H on C2
3.) What are the names of all the nitrogenous bases? Which are purines and which are pyrimidines?
What general structural characteristic distinguishes purines from pyrimidines?
a. Adenine, Guanine, Cytosine, Thymine, Uracil
b. A and G = purines, C, T, U = pyrimidines
c. A and G are larger—they have the extra 5C cyclic ring attached.
4.) How do DNA and RNA differ in:
a. Function
i. DNA stores genetic info
ii. RNA has potential for multiple fxns and structures
b. Composition
i. Deoxyribose vs ribose
5.) What reaction joins nucleotides in a DNA and RNA chain? What is the name of the bond that
forms? What molecule is released from this reaction? What components of the nucleotide are
interacting in this reaction?
a. Polymerization (condensation) rxn.
b. Phosphodiester linkage (bond)
c. H2O released (condensation)
d. Phosphate OH on one nucleotide with OH attached to C3 of nitrogenous base of
another nucleotide
6.) What two interactions are occurring in the DNA double helix? Explain each. Together, both yield
what structural benefit for the helix?
a. Complementary base pairing and Base stacking by hydrophobic interactions
b. Provides stability
7.) The directionality of the nucleotide sequence is read in what direction?
a. 5’  3’ (because of phosphodiester linkage between 5’C of one nuc with 3’C of
another nuc.  one end of the sugar-phosphate backbone has an unlinked 5’
phosphate while the other end has an unlinked hydroxyl
8.) How many bonds form between Guanine and cytosine versus adenine and thymine? How does
heat denaturation affect these bonds? Therefore, how would you expect the composition of G’s
and C’s vs A’s to T’s to differ in the DNA of an organism that lives in very high temperatures
versus low temperatures?
a. 3 H bonds between G---C | 2 H bonds between A and T
b. Heat denaturation breaks H bonds
c. A higher concentration of G---C would provide the most stability against heat
denaturation
9.) What are the general steps in DNA synthesis? What catalyzes polymerization in cells?
a. Strand separation
b. Base-pairing
c. Polymerization---Catalyzed by DNA polymerase
10.) How does the secondary structure of RNA differ from that of DNA? What about tertiary
structure?
a. RNA has hairpin loop + helices. DNA has beta sheets and alpha helices
b. RNA can form tertiary. DNA has no tertiary structure
11.) What are the major types of RNA?
a. Ribosomal
b. Messenger
c. Transfer
d. Small nuclear
e. Micro
12.) What protein enzyme catalyzes splicing of introns in “precursor” rRNA? What did this discovery
indicate?
a. RNA is catalytic—ribozyme
13.) What is the function of most ribozymes? What do rRNA catalyze during translation?
a. Most catalyze the breaking of phosphodiester bonds
14.) What are the components of the RNA World Hypothesis?
a. RNA replicates itself
b. Self-replicating RNA also catalyzes protein synthesis
c. DNA becomes the genetic material and codes for RNA
Chapter 5: Introduction to Carbohydrates
Lecture 5 PPT Review:
1.) What is a monosaccharide? What is the general formula for a monosaccharide? What structure
allows monosaccharides to form polysaccharides?
a. Monosaccharide = molecule that has molecular formula (CH2O)n and cannot be
hydrolyzed to form any smaller carbs
b. Forms polysaccharides via glycosidic linkages
2.) What do the functional groups tell you about the properties of monosaccharides? (3 discussed
in lecture)
a. Polar
b. Hydrophilic
c. Forms Hydrogen bonds
3.) What is the structural difference between
a. Aldose and ketose
i. Aldose has carbonyl at end of chain/Ketose has carbonyl in middle of chain
b. Glucose and galactose
i. Differ only by positioning of one hydroxyl OH on C4
4.) Review ring structure conformation of sugar using α- and β-glucose example. Why can sugars
form the ring structure?
a. Ring structures are more stable in ring structures—which is favorabletherefore
occurs spontaneously
5.) How are disaccharides formed? How does the structure of fructose differ from glucose?
a. Condensation Rxn
b. Fructose is 5C ring
6.) Complete the following reaction:
a. Gives you fructose and glucose
7.) What is the role of glycoproteins in cell identity?
a. Each cell in your body has glycoproteins on its surface that identify it as part of your
body (important for immune system!)—Keep in mind that there are huge potential for
oligosaccharides to be unique, therefore each cell type and species can display a
unique identity
8.) What are two of the major roles of polysaccharides discussed in class?
a. Energy storage depots
b. Structural scaffolds
9.) Compare/contrast the types of polysaccharides by each of the following:
a. Roles/Uses
b. Glycosidic Linkage/Chemical Structure
c. 3D structure
d. Use table 5.1 in book to review this
10.) Difference between Amylose and Amylopectin?
a. Amylose has unbranched helices while amylopectin has branched helices
11.) Explain the role of carbohydrates in chemical energy storage.
a. Starch and glycogen can convert glucose to ATP
12.) What feature makes cellulose, chitin, and peptidoglycan advantageous for organismal
structures? Explain why.
a. The beta1,4 glycosidic linkages are 1.) Difficult to hydrolyze and 2.) very few enzymes
have activate sites that accommodate their geometry
Chapter 6: Lipids and Getting Across Cell Membranes
Lecture 6 PPT Review:
1.) Describe the solubility of lipids.
a. Insoluble or only slightly soluble in H2O
2.) What are the general structural components that form fats and oils? Draw the general structure
of a triglyceride.
a. Glycerol w/ ester linkages attaching fatty acids (hydrocarbon chains)
3.) What attributes determine the properties of fats? Compare and contrast saturated vs
unsaturated fats at room temperature (that we discussed in lecture—think back to video).
a. SaturatedNo double bonds, linear structure, high melting point, solid at RT, “fat”
b. Unsaturated  double bonds, kink in structure, low melting point, liquid at RT, “oil”
4.) Why are phospholipids structurally important for eukaryotes? What are the structural
components? Describe the hydrophobicity of these components.
a. Essential for cell membrane—serving as barrier to outside world
b. Amphipathichas polar, charged, hydrophilic head (interacts with surrounding H2O),
and hydrophilic tail
5.) What is selective permeability? What two characteristics of a molecule is permeability
dependent on? Arrange the following in terms of highest to lowest permeability:
CO2
Na+
Sucrose
N2
ClO2
Glycerol
H2O
K+
Glucose
- O2, CO2, N2 > H2O, Glycerol > Glucose, Sucrose > Cl-, K+, Na+
- Permeability is dependent on temperature and fluidity
6.) What is the net water movement via osmosis under the following conditions? Describe the
outcome/appearance for a RBC under these conditions, as well.
a. Isotonic – concentration is at equilibrium
b. Hypertonic – high solute concentration outside of cell, so H2O moves out of cell to
balance
c. Hypotonic – high solute concentration inside the cell, so H2O moves from outside the
cell to inside to balance concentrations
7.) What is facilitated diffusion? How are ions passing through the membrane? (think
concentration gradient) Does this transport require energy? What are allosteric proteins? What
example was used in class to supplement this?
a. Specific molecule binds to carrier protein in the membranewhich causes
CCcausing molecule to travel down concentration gradient (so no energy required).
Going from high concentration to low concentration**
b. Allosteric proteins undergo shape change caused by binding (or other interaction)
with another molecule/protein
c. GLUT1 protein example
8.) What is active transport? How are ions passing through the membrane? (think concentration
gradient) Does this transport require energy? What example was used in class to supplement
this?
a. Transporting molecules from low concentration to high concentration (against
concentration gradient) therefore ATP input is required. ATP causes carrier protein to
change shape and then allows transport.
9.) Permeability is a function of what two parameters? How does the structure of the bilayer
influence these?
a. Temperature and fluidity
b. Short and unsaturated lipid bilayer = higher permeability and fluidity
c. Long and saturated lipid bilayer = lower permeability and fluidity
10.) What structural component of steroids distinguishes these lipids from others? What example
from lecture did we discuss? What 2 functions did we discuss this example as having?
a. The four cyclic rings
b. Cholesterol—cell membrane component and precursor of vitamin D and sex steroid
hormones
11.) Review the Question box from Chapter 6 included in the lecture.
12.) Review transport animations
Chapter 7: Inside the Cell
Lecture 8 PPT Review “Inside the Cell: The Dynamic Cell—Intracellular Transport”
1.) What is the central dogma in biology? (will be discussed in more detail in later lectures)
a. DNARNAProtein
2.) How do proteins get targeted to their correct destination in the cell?
a. Localization signal/sequence
3.) Where does protein synthesis occur in the cell? How do mRNAs get out of the nucleus? How do
nuclear proteins get into the nucleus?
a. Ribosomes
b. mRNAs exit through NPCs
c. Nuclear proteins would need NLS to get into nucleus
4.) Outline as many components of the nucleus as you can—think about nuclear import, export,
anatomy of nucleus, nucleic acid synthesis.
5.) What structures serve as a passageway into and out of the nucleus?
a. Nuclear Pore Complex
6.) What is the name of the amino acid sequence present in all nuclear proteins? What is its
function? What family of proteins interacts with these amino acid sequences?
a. Nuclear Localization signal
b. Localizes proteins to the nucleus—allows entry into nucleus
c. Importins
7.) Outline the steps in the endomembrane system using RNA that has just been
synthesized/transcribed.
a. Ribosome
b. RER
c. Transport to cis golgi
d. Cis to trans golgi
e. Golgi packages to be released to destination
8.) What is the signal hypothesis? How does it explain the differences between the “signals”
present within the AA sequence of an ER protein versus a nuclear protein? Include the
modification to the ER protein that we discussed in class.
a. Difference is that ER signal sequence is cleaved whereas nuclear localization signal
remains intact. Caused by post translational modification
9.) What is glycosylation? What type of modification is this an example of? Be sure you can identify
what the macromolecules are on this slide and any other example.
a. Addition of a carbohydrate (sugar) to a molecule
10.) Why would a protein travel from the ER to the golgi? What is the protein transported in?
a. Proteins getting different places in the cell need to be “packaged” into vesicles to get
to other places
11.) A protein designated for the lysosome would have what unique signal/tag/sequence within its
amino acid sequence?
a. Mannose-6-phosphate
Lecture 9 PPT Review “Inside the Cell: The Dynamic Cytoskeleton”
1.) Why would the cytoskeleton be characterized as dynamic?
a. Expands and contracts over time
2.) What are the three major elements of the cytoskeleton? Arrange them in order of greatest to
smallest size.
a. Microfilaments
b. Intermediate Filaments
c. Microtubules
3.) What is the globular protein that forms microfilaments? Describe subunits of this protein.
Describe polarity for this protein?
a. Actin—the microfilament is composed of polymerizing and depolymerizing actin
subunits
b. Has positive and negative end
4.) What is treadmilling?
a. Filaments polymerize and depolymerize
5.) What is myosin classified as? How does it perform its function? What reaction is involved?
a. Motor Protein
b. Converts chemical energy in ATP into mechanical work—Converts ATP to ADP which
causes a shape change that extends the head region, attaches it to actin, and then
contracts to pull itself along the actin filament---this shape change causes the actin
and myosin to slide past each other.
c. ATP hydrolysis
6.) What are 3 different types of movement that can occur through actin-myosin interactions?
a. Cell crawling
b. Cell division
c. Cytoplasmic streaming in plants
7.) What is the primary protein that form intermediate filaments (that we discussed)? What are
two functions of this protein?
a. Keratin
b. Functions = maintain cell shape by resisiting tension and anchor nucleus and some
other organelles
8.) Describe polarity and “treadmilling” in intermediate filaments.
a. Each end is identicaldoes not treadmill
9.) What are the proteins that make up the composition of microtubules?
a. Tubulin—Has alpha and beta tubulin dimers
10.) List a few functions of microtubules? (There are two that were outlined in the PPT). Describe the
polarity and “treadmilling” of microtubules.
a. Functions = move organelles and provide tracks for intracellular transport
b. Each end has distinct polaritytreadmilling can occur
11.) How are microtubules linked with the following: (Also list the motor proteins involved in each)
a. Vesicle movement
i. Kinesin w/ ATP moves cells along microtubule tracks (Watch video)
b. Whole cell movement (think cilia + flagella)
i. Dynein w/ ATP—flagella are made of microtubules that whip back and forth
12.) What is an axenome?
a. 9 doublets + 2 central microtubules
13.) Watch “The Inner Life of the Cell” and work on understanding each aspect of the video—always
good to have a visual memory to refer back to when you get stuck on questions!
Chapter 12: The Cell Cycle
Lecture 10 “Control of Cell Cycle” PPT review:
1.) Watch the Mitosis video from lecture. What are the different phases of mitosis? What happens
at each phase?
a. Interphase—after chromosome replication, each chromosome is composed of two
sister chromatids. Centrosomes have replicated
b. Prophase—Chromosome condense and spindle apparatus begins to form
c. Prometaphase—Nuclear envelope breaks down. Microtubules contact chromosomes
at kinetochores.
d. Metaphase—Chromosomes complete migration to middle of cell
e. Anaphase—Sister chromatids separate into daughter chromosomes and are pulled to
opposite poles by spindle apparatus
f. Telophase—The nuclear envelope re-forms, and chromosomes de-condense
2.) What are the phases of the cell cycle? What occurs during Gap phases? Explain the G0 phase.
a. G1 growth to accommodate new genetic info—organelle replication (and in G2) etc
b. S phase—DNA synthesis
c. G2—constructs microtubules, prepares mitotic proteins, cytoplasm growth etc
3.) Define the following:
a. MPF—M-phase promoting factor = a complex of a cyclin and CDK that when activated
will phosphorylate a number of proteins needed to initiate mitosis in eukaryotic cells
b. Cdk—cycling dependent kinase = protein kinase that is functional only when bound to
a cyclin and are activated by other modifications.
c. Cyclin = regulatory protein whose concentrations fluctuate cyclically throughout the
cell cycle. Involved in control of cell cycle via cdk.
4.) How are Cdks activated? Explain the accumulation and degradation of cyclin in cells.
a. Has to bind to cyclin
5.)
6.)
7.)
8.)
b. Cyclin concentration increases during interphase and peaks in M phase, where it is
then destroyed
What is the relationship between concentrations of cyclin and activity of MPF?
a. When cyclin concentrations are high, more MPF is active
What is the function of Cdk? (include the reaction it’s involved in)
a. Cdk is a protein kinase. It phosphorylates protein targets.
There are 3 cell cycle checkpoints we discussed in lecture:
a. What occurs at each checkpoint/What is being “checked”?
i. G2—Checking if the DNA is both replicated and undamaged
ii. M-Phase—Checking if chromosomes have attached to the spindle apparatus
and that the chromosomes have segregated properly
iii. G1—Checking if the cell is large enough, has enough nutrition to proceed
through the rest of the CC, and that the DNA is undamaged
b. State whether MPF is present or absent.
i. G2—MPF present
ii. M-phase—MPF absent
Explain how the G1 checkpoint is subject to social control using the slides from lecture or book.
What is acting as the “social control” in this? (p. 234 in text)
1. Growth factors arriving from other cells and stimulate the production of E2F and G1
cyclins
2. Rb binds to E2F, inactivating it. G1 cyclins form cyclin-Cdk dimers. The dimers are
phosphorylated which inactivates them
3. The inactivating phosphate on the cyclin-Cdk dimer is removed
4. Active Cdk phosphorylates Rb
5. Phosphorylated Rb releases E2F
6. E2F stimulates production of S-phase proteins
a. The growth factors (keep in mind these are from other cells though) are acting as
social signals triggering the Rb protein to be overridden—allowing E2F to help
progress the cell to S-phase
9.) What characterizes cancer on a cellular level?
a. Uncontrolled cell growth, accumulation of genetic changes
10.) If a cancer cell divides without growth factors, which checkpoint does it bypass? Explain why
cancer cells passing through this checkpoint is a problem—think about what occurs at the phase
following G1.
a. G1 phase
b. Problem because G1 checkpoints are checking for DNA damage (among other things).
Therefore, if these checkpoints are not operating properly and the cell passes through
unchecked, DNA damage will be present in the DNA when replicated.
11.) During what phases in the cell cycle would you expect there to be large changes in the
polymerization or depolymerization of microtubules?
a. Polymerization—while the mitotic spindle is forming—prophase
b. Depolymerization--Anaphase
12.) When actively growing cells are treated with Taxol, they often are unable to complete the cell
cycle. Based on what you have learned about cell-cycle checkpoints, which checkpoint likely
causes these cells to arrest?
a. Taxol inhibits cell cycle at Metaphase of M-phase
Chapter 8: Energy and Enzymes: An Introduction to Metabolic Pathways
Lecture 11 “Energy and Enzymes” PPT Review:
1.) What is the 1st law of thermodynamics?
a. States that energy can be transferred and converted into different forms, but it cannot
be destroyed
2.) Explain potential and kinetic energy—using one of the examples from class may be a good way
to practice this.
a. Potential energy is energy associated with position or configuration—stored energy
b. Kinetic energy is energy of motion
c. In the waterfall example from class: A water molecule at the top of a molecule has
high potential energythen as it falls the energy is converted to kinetic energyonce
it strikes the rocks at the bottom, the kinetic-motion energy is converted to other
kinds of energy (included mechanical, heat, sound)
3.) What is the second law of thermodynamics? Where is potential energy stored in a molecule?
a. Second law states that entropy will always increase in an isolated system
b. Potential energy is stored in the chemical bonds of a molecule
4.) If a reaction is favorable in the direction of reactantsproducts:
a. Which would have the highest potential energy?
i. Reactants
b. Would the entropy be high or low in the High PE component?\
i. Low entropy (More ordered)
5.) What is a redox reaction? What is oxidation? What is reduction? Is oxygen usually an e- acceptor
or donor?
a. Redox rxn = a chemical reaction that involves the loss or gain of one or more electrons
b. Oxidation is the loss of electrons
c. Reduction is the gain of electrons
d. Oxygen is usually the electron acceptor
6.) Compare and contrast Reduced molecules and Oxidized molecules by expressing:
a. Bonds that are in high quantity
i. Reduced = C-H
ii. Oxidized = C-O
b. Level of potential energy (high or low)
i. Reduced = many C-H with high PE
ii. Oxidized = many C-O with low PE
7.) Define:
a. Exothermic reaction
i. A chemical reaction that can occur spontaneously, releasing heat and/or
increasing entropy, and for which the Gibbs free energy is less than zero
b. Endothermic reaction
i. Chemical reaction that requires an input of energy to occur and for which the
Gibbs free energy is greater than zero.
8.) Why are endergonic reactions linked to exergonic reactions in cells? –> So why is ATP hydrolysis
an important reaction in cellular energetics?
a. Endergonic reactions require an input of energy—Exergonic reactions release energy.
Therefore, the energy released by the exergonic reaction can be used to drive the
endergonic reaction forward
b. ATP hydrolysis releases high amount of energy and can initiate many of the cell’s
endergonic reactions
9.) What structural component of ATP causes it to have potential energy stored within the
molecule?
a. The triphosphate component has the (-) charges of each phosphate in close proximity.
Since like charges repel each other, this makes hydrolysis very favorable (exergonic) to
relieve the repulsion between the (-) charges
10.) What is the activation energy of a reaction? How do molecules deal with this?
a. The amount of energy required to initiate a chemical reaction; specifically the energy
required to reach the transition state
b. Energy molecules must collide in precise oritentation and overcome mutual
repulsion—enzymes help to lower the activation energy
11.) Define:
a. Enzyme
i. A globular protein that is specialized to serve as a catalyst
b. Catalyst
i. A substance that lowers the energy of activation for a reaction by forming a
temporary association with the reacting molecule
12.) Draw the generic energy profile that we looked at in lecture. Include:
a. Reactants
b. Transition State
c. Products
d. Label the x and y axis
e. State whether your rxn is exergonic or endergonic
f. Ea
g. ΔG
h. Figure 8.11 and 8.12 in text shows energy diagrams from class
13.) Explain induced fit using the reaction above. Would the cell be able to utilize an enzyme after it
undergoes the reaction we examined in lecture? Why?
a. Induced fit is a change in the shape of an enzyme’s active site in response to the initial
binding with a substrate. In the example from class, the substrate binds to the active
site of the enzyme which causes a shape change in the active site. The shape change
allows the active site to bind to the substrate more tightly which lowers Act. Energy
b. Yes, the enzyme is not consumed during the reaction. The reason that it isn’t bound
anything in the final step is because the products of the reaction bind with lower
affinity and therefore release. However, the same substrates would be able to bind
and initiate the reaction again.
14.) What is allosteric activation? What is allosteric inhibition? What is competitive inhibition?
a. Allosteric activation and inhibition involve a substrate binding to a site on the enzyme
other than the active site which causes a conformational change that makes the active
site available (allosteric activation) or unavailable (allosteric inhibition)
b. Competitive inhibition occurs when the active site of the enzyme is occupied by a
molecule that isn’t the enzymes normal substrate. Hence, the alternate molecule is
competing with the normal substrate.