Ch.9 [Cell Respiration, Glycolysis, Pyruvate Processing, TCA Cycle]

True or false? Enzymes in the pathway of cellular respiration are only used for breaking down carbohydrates to produce cellular energy.

False

Which of the following pathways in cellular respiration occurs in the cytosol of a cell?

Glycolysis

Which method of ATP production is driven by a chemical concentration gradient?

Oxidative phosphorylation

Which of these pathways in cellular respiration produce ATP by substrate-level phosphorylation? Select all that apply.

-TCA cycle

-Glycolysis

Which of the following is consumed in glycolysis?

ATP

What type of reaction involves a rearrangement of chemical bonds in a molecule while maintaining the same chemical formula?

Isomerization

Which type of reaction would be catalyzed by a kinase?

Phosphorylation

Which is true about the energy investment phase of glycolysis?

-ATP is consumed

-Two phosphate groups are added to a molecule before cleaving it

-A phosphate group is added to glucose

Which of the following is true about the energy payoff phase of glycolysis?

-A phosphate group is added to a 3 carbon compound

-4 ATP are produced by substrate level phosphorylation

Q//Based off what you've learned about the different reactions in glycolysis, which step do you think would be the major point of regulation?

-phosphofructokinase-1 (PFK-1). Because:

-It's irreversible under normal cellular conditions, committing glucose to continue

through glycolysis.

-It's allosterically regulated — meaning its activity changes depending on the cell's energy needs.

Because of these factors, PFK-1 acts as the main control point — it decides whether the cell keeps breaking down glucose for energy or slows glycolysis when energy is already sufficient.

Which of the following would decrease the rate of glycolysis?

-citrate

-ATP

Q//Which site of PFK - the active site or the allosteric site - do you think has a higher binding affinity for ATP? Why?

The active site has a higher binding affinity for ATP because it must efficiently bind ATP even when energy levels in the cell are low, allowing the enzyme to catalyze the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate. In contrast, the allosteric site has a lower affinity for ATP, meaning ATP will only bind there when its concentration is high. When ATP binds to this allosteric site, it acts as an inhibitor, signaling that the cell already has enough energy and slowing down glycolysis. This difference in binding affinities allows the enzyme to balance energy production with the cell's energy needs.

Which of the following is true about pyruvate oxidation?

CO2 is produced

Where in the mitochondria does pyruvate oxidation take place?

Mitochondrial matrix

Which of the following would inhibit pyruvate oxidation?

-ATP

-NADH

True or false? Coenzyme-A is used to deliver acetyl groups.

True

How many molecules of CO2 are produced from one turn of the tricarboxylic acid cycle?

2 CO2

In the tricarboxylic acid cycle, two carbons from acetyl CoA are added to a ___ carbon compound. Then, ____ carbon(s) is/are removed to generate a ____ carbon compound.

4, 2, 4

Dehydrogenases in the TCA cycle catalyze...

redox reactions

Take a look at the simplified diagram of the TCA cycle. How many reactions would be catalyzed by a dehydrogenase?

4

Which of the following would decrease the rate of the TCA cycle?

NADH, ATP

True or false? The carbons in citric acid cycle intermediates are always completely oxidized.

True

How many molecules of reduced electron carriers are produced from one molecule of glucose?

12