Unit 4: Energy Flashcards
One of the results of the TCA cycle is the ______________?
a) oxidation of NAD+
b) reduction of NAD+
c) oxidation of NADH
d) reduction of NADH
B) reduction of NAD+
During aerobic cellular respiration, the carbons present in pyruvate are initially derived from _______ and are ultimately converted to _______
glucose and CO2
Which reactant molecule becomes reduced in the following chemical equation?
glyceraldehyde 3-phosphate + NAD+ + Pi –> 1,3-diphsophoglycerate + NADH + H+
NAD+
Substrate level phosphorylation…..
a) requires the presence of oxygen as the terminal electron acceptor
b) happens only in the mitochondria, therefore only occurs in eukaryotic cells
c) refers to the enzyme-catalyzed transfer of an activated phosphate group to form a nucleoside triphosphate
d) a and c
e) a b and c
c)
Two ATP molecule are ‘spent’ in the energy investment phase of glycolysis. Why is this energy necessary to begin the process of glucose catabolism?
a) It isn’t ; glucose contains 686 kcal/mol in its chemical bonds, so its catabolism is spontaneous
b) it is needed to generate the electron carrier NAD+
c) it is needed to prime the enzymes of glycolysis
d) some energy must be invested to make glucose more reactive
d) some energy must be invested to make glucose more reactive
What does the enzyme phosphofructokinase catalyze?
phosphorylation of fructose 6-phosphate to form fructose 1,6-biphosphate
What compound is most likely to inhibit the pyruvate dehydrogenase enzyme complex through a mechanism of feedback regulation?
NADH
Fatty acids are catabolized by a process called beta-oxidation. The end-products of the metabolic pathway are acetyl groups of acetyl CoA molecules. Where would these acetyl groups enter the energy pathway?
Citric Acid Cycle / Krebs Cycle
What importance do fermentation reaction give to cells?
Regenerate NAD+
In a chloroplast of a plant cell actively engaged in photosynthesis, you would expect the pH to be?
lower in the thylakoid space than in the stroma
Why does NADH produce more energy than FADH2?
NADH passes its electrons through 3 proton pumps. FADH2 binds to ubiquinone and passes its electrons through only 2 proton pumps
Why does the oxidation of sugar produce less energy than the direct burning of sugar?
Oxidation of sugar it done through a multitude of steps, each having its own activation energies, each losing heat each time
Is NADH in an oxidized or reduced form?
Reduced
Where does the breakdown of glucose into 2 pyruvate molecules occur?
Cytosol
Do all NADH molecules produce the same amount of energy?
NADH molecules produced during the glycolysis stage produce less energy. Because they are made in the cytosol of the cell, they have to be transported over to the mitochondrial membrane to be used in the ETC
Where is the Krebs Cycle located?
Mitochondrial matrix
What is the major contributor of proton force that is responsible for generating ATP through chemiosmosis?
The charge difference between the intermembrane space (positive) and mitochondrial matrix (negative)
Example of a cell that can behave as facultative anaerobes
muscle cells
Example of a cell that cannot behave as facultative anaerobe and why?
neuron cells, they require more than the 2 ATP/glucose molecule to keep functioning
What are the key differences between chloroplasts and mitochondria?
Chloroplasts are larger, contain thylakoids - only have 1 proton pump (only 1 non-permeable membrane so they can create bigger differences in pH)
Why does Krebs Cycle stop when there is no oxygen?
Oxygen is the final acceptor in the ETC. This causes a backup in oxidative phosphorylation, and a buildup of loaded energy carriers that are waiting to be oxidized (FADH2, NADH). Without being able to take off H, the Krebs cycle and the only process that can occur is glycolysis
The conversion of pyruvate to acetyl CoA occurs
a) through 4 enzymatic reactions mediated by the pyruvate dehydrogenase complex
b) in the mitochondrial matrix, after moving across the inner and outer mitochondrial membrane
c) In the cytoplasm prior to transport into the mitochondrial matrix
d) to oxide and activate the pyruvate molecule so it can enter the TCA cycle
e) b and d
e)
What is the function of coenzyme A in the TCA cycle?
a) Coenzyme for the decarboxylation of pyruvate
b) Coenzyme of redox reactions
c) Coenzyme of dehydration reactions
d) activates a two carbon acyl group derived from pyruvate
e) It prepares NADH and FADH2 for oxidative phosphorylation
d)
Following glycolysis and the TCA cycle and before the ETC and oxidative phosphorylation, the carbon skeleton of glucose has been broken down to Co2. Most of the energy from the original glucose at this point is still in the form of:
a) ATP
b) NAD+
c) CO2
d) carbon-hydrogen bonds
e) NADH
e)
In the breakdown of glucose, where is most of the water produced from?
a) glycolysis
b) TCA cycle
c) fermentation
d) ETC
d) ETC
If glucose is fully labeled with radioactive C-14, what molecule will become radioactive as glycolysis and the TCA cycle are completed?
a) H2O
b) CO2
c) ATP
d) NADH
e) CoA
b)
The fermentation pathway allows:
a) the extraction of additional energy through the further oxidation of glucose
b) the glycolytic pathway to continue by providing an alternative electron acceptor for the regeneration of NAD+
c) a mechanism for certain tissues to function under oxygen depleted conditions
d) the TCA cycle to continue to function in the absence of oxygen
e) b and c
e)
