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Chapter 5
Cell Respiration and Metabolism
Glucose:
Cellular respiration: glucose is broken down to form ________________
–Requires oxygen =
–Lack of oxygen =
•Forms ________________________ as the end product
Metabolism
Divided into 2 categories:
–Catabolic:
•_____________________.
•Breakdown larger organic molecules into smaller molecules.
•Serve as primary sources of energy for synthesis of __________________
–Anabolic:
•Require ________________ of energy.
•Synthesis of large energy-storage molecules.
Glycolysis = ____________________________________
Metabolic pathway by which glucose is converted to _______ molecules of
__________________________________.
Glucose must be _____________________ first before energy can be
obtained.
–_____________________ consumed at the beginning of glycolysis.
Net gain of 2 ATP, 2 NADH, + 2 H+.
Lactic Acid Pathway
Metabolic pathway by which glucose is converted to lactic
____________________________________________________
–Oxygen is __________________ used in the process.
Produce _________________________ molecule.
Lactic Acid Pathway (continued)
Some tissues better adapt to anaerobic conditions:
–________________ do not contain mitochondria and _____________use the
lactic acid pathway.
–Occurs in _______________________ and _________________when ratio of
oxygen supply to oxygen need falls below critical level.
•Skeletal muscle:
–Normal daily occurrence.
–Does not harm muscle tissue.
•Cardiac muscle normally respires _____________________:
–_______________________________
occurs under anaerobic conditions.
Glycogenesis and Glycogenolysis
Cells cannot store many __________________ molecules.
Increased intracellular ______________________ increases
__________________pressure, drawing ________________into the cell.
Many organs must store _____________________ in form of _____________.
–Glycogenesis: _________________________________________________
–Glycogenolysis: __________________________________________________
Glycogenesis and Glycogenolysis (continued)
_______________________________ cannot leak out of the cell.
___________________________ generate glucose-6-phosphate for
own
glycolytic needs.
Liver contains the enzyme ___________________________________ that can
remove the phosphate group and produce free glucose.
Aerobic Respiration
The ______________________ formed by glycolysis enters interior of
___________________________
Converted by __________________________ to 2 molecules of
___________________________________________
Acetyl CoA serves as substrate for mitochondrial enzymes in the aerobic
pathway.
Krebs Cycle (Citric Acid Cycle)
Acetyl CoA subunit combines with oxaloacetic acid to form
________________________________
Citric acid enters the _____________________________.
–Through a series of reactions, citric acid is converted to
_________________________ to complete the pathway.
Produces:
1 GTP, 3 NADH, and 1 FADH2
–NADH and FADH2 transport __________________ to Electron Transport
System (ETC).
Krebs Cycle (Citric Acid Cycle) (continued)
Electron Transport and Oxidative Phosphorylation
Cristae of inner _______________________ membrane contain molecules that
serve as an electron transport system during aerobic respiration.
–Electron transport chain consists of _______________________________),
coenzyme Q, and cytochromes.
–Each ____________________________ transfers electron pairs from NADH
and FADH2 to next cytochrome.
•Oxidized NAD and FAD are regenerated and shuttle electrons from the
________________Cycle to the ETC.
Cytochrome receives a pair of ___________________.
–_____________________ reduced, then oxidized as electrons are transferred.
Electron Transport
Cytochrome a3 transfers electrons
Oxidative phosphorylation occurs:
–Energy
to O2 (final electron acceptor).
derived is used to _________________________________ to ATP.
ATP Balance Sheet
Direct substrate phosphorylation (glycolysis):
–Net gain of _____________________.
Oxidative phosphorylation:
–2.5 ATP produced for pair of electrons each NADH donates.
–1.5 ATP produced for each pair of electrons FADH2 donates (activates 2nd and
3rd proton pumps).
–Net of __________________ATP produced.
Lipid Metabolism
When more energy is taken into the body faster than consumed,
___________________________________
Glucose converted into ___________________________________________..
Lipogenesis
Formation of ______________________
____________________________ subunits from acetyl CoA converted into
various lipids.
Occurs mainly in ____________________________________
Lipid Metabolism
Lipolysis:
–____________________________________
Triglycerides:____________________________________
__________________________________ serve as blood-borne energy
carriers.
–Free fatty acids serve as the ___________________________ source derived
from triglycerides.
Breakdown of Fat: Beta-Oxidation
Enzymes remove
____________________ acetic acid molecules from acid end of fatty acid chain.
–Forms ____________________________
Acetyl CoA enters ________________________________.
–_____________________________________________
Brown Fat
Amount of brown fat ___________________________________________.
Major site for __________________________________ in the newborn.
Brown fat produces an uncoupling protein, _____________________to leak
out of inner mitochondrial membrane.
–Less ________________________ produced, causes electron transport
system to be more active.
Ketone Bodies
______________________________ in adipose tissue broken down and
resynthesized.
–Ensure the blood will contain sufficient levels of _________________________
for aerobic respiration.
•May be hydrolyzed to _______________________________________.
If _____________________ sufficient, acetyl CoA channeled into alternate
pathway.
–Converted to ______________________ bodies.
Amino Acid Metabolism
Nitrogen is ingested primarily as _________________________
Excess nitrogen is excreted mainly as _______________________.
Nitrogen balance:
–____________________________________________________
__________N balance:
–Amount of nitrogen ingested more than amount excreted.
_________ N balance:
–Amount of nitrogen excreted greater than ingested.
In healthy adults the amount of nitrogen excreted = amount ingested.
Transamination
Adequate amounts of __________________ are required for
_______________ and repair. A new amino acid can be obtained by
________________________________.
N = ingested as proteins via _________________________________
N = excreted mainly as ___________________________
Excess _________________________ : body takes off N, uses C skeleton for
energy/fat
See figure 5.16
Essential vs Nonessential AA
Essential
1. Arginine
2. Histidine
3. Isoleucine
4. Leucine
5. Methionine
6. Phenylalanine
7. Threonine
8. Tryptophan
9. Valine
10. Lysine
Nonessential
1. Alanine
2. Asparagine
3. Aspartic Acid
4. Glutamic Acid
5. Glutamine
6. Glycine
7. Proline
8. Cysteine
9. Serine
10. Tyrosine
Uses of Different Energy Sources
Not all cells can use ________________ as the energy source.
Blood contains a variety of energy sources:
–________________________________________________________
Brain uses _______________as its major source of energy.
–Blood [glucose] maintained as many organs spare glucose.
Uses of Different Energy Sources (continued)