Metabolic Reactions

Question 1

Catabolic pathways in Mitochondria

Answer 1

• CAC
• ETC
• Mitochondrial ATP synthesis (i.e., oxidative phosphorylation)

Question 2

Succinyl-CoA and acetyl-CoA

Answer 2

Identifiable by their thioesters (S-CoA)

Question 3

Citrate

Answer 3

Six-carbon molecule that is synthesized in the first step of the CAC when acetyl-CoA combines with OAA

Question 4

Oxaloacetate (OAA)

Answer 4

Four-carbon molecule that forms in the last step of the CAC when malate is oxidized

Question 5

α-ketoglutarate

Answer 5

Five-carbon molecule that forms in the CAC when isocitrate releases CO2

Question 6

Pyruvate

Answer 6

Three-carbon molecule produced in the cytosol after the final step of glycolysis
After pyruvate is synthesized, it is transported to the mitochondria, where it is decarboxylated to form acetyl-CoA.
Acetyl-CoA then enters the CAC

Question 7

Inhibition of Complex I

Answer 7

Result in the buildup of NADH and the depletion of the downstream electron carriers

Question 8

Inhibition of Complex II

Answer 8

Result in the depletion of the downstream electron carriers ubiquinol, and cytochrome C

Question 9

Inhibition of Complex IV

Answer 9

All the reduced electron carriers would eventually build up, including cytochrome C, because each would ultimately lose the ability to transfer its electrons to the next acceptor

Question 10

Decoupling

Answer 10

Protons that enter the mitochondrial matrix passively do not interact with ATP synthase, so they do not drive ATP synthesis
The rate of ATP synthesis decreases in the presence of a passive transport molecule

Question 11

Enzymes of the CAC

Answer 11

Complex II/succinate dehydrogenase, fumarase, malate dehydrogenase, citrate synthase, aconitase, isocitrate dehydrogenase, and succinyl-CoA synthetase

Question 12

Enzymes of the ETC

Answer 12

Complex I, Complex III, Complex IV, and Complex V/ATP synthase

Question 13

Decouping the ETC from ATP synthesis

Answer 13

Results in increased oxygen consumption and decreased ATP synthesis

Question 14

Loss of function mutation in the p53 tumor suppressor gene affects the PPP by:

Answer 14

Upregulating G6PD activity and increasing PPP metabolic activity; upregulation happens when a protein can no longer suppress the activity

Question 15

Compared to NADPH, NADH is prominently involved in:

Answer 15

Catabolic reactions; both undergo oxidation-reduction reactions

Question 16

NADPH

Answer 16

Used to generate precursors for macromolecules such as lipids and nucleic acids

Question 17

Anabolism

Answer 17

Process of building larger molecules

Question 18

NADH

Answer 18

Plays a significant role in glycolysis

Question 19

Catabolism

Answer 19

The process of breaking down molecules

Question 20

Increased glycolytic production of glyceraldehyde 3-phosphate

Answer 20

Will increase production of ribose 5-phosphate

Question 21

RQ: High 1 min into a vigorous workout, then plateaus, why?

Answer 21

The RQ was higher initially because there was greater glucose consumption, as a relative proportion of metabolism

Question 22

Disorders that increase the metabolic breakdown of which of the following biological molecules are considered a direct risk factor or uric acid kidney stones?

Answer 22

ATP and DNA

Question 23

Eukaryotic cells use both:

Answer 23

NADPH and NADH are the electron carriers

Question 24

NADH

Answer 24

Used in the breakdown of glucose for the formation of ATP

Question 25

NADPH

Answer 25

Used as reducing equivalent with glutathione

Question 26

Pentose phosphate pathway

Answer 26

The purpose is to regenerate NADPH High levels of substrates tend to stimulate their metabolic pathways, thus NADP+ stimulates the pentose phosphate pathway

Question 27

NAD+

Answer 27

Product of the electron transport chain, NADH is a substrate

Question 28

Translation regulation

Answer 28

Occurs when the translation of RNA to protein is a regulated step

Question 29

Acetyl-CoA

Answer 29

Product of fatty acid breakdown that enters the TCA cycle

Question 30

Glycerol

Answer 30

Breakdown product of triacylglycerols, not FA

Question 31

Malonyl-CoA

Answer 31

Does not enter TCA or produce ATP

Question 32

Support for the chemiosmotic theory

Answer 32

Decoupling agents such as DNP block ATP synthesis; ATP synthesis is blocked when the physical continuity of the mitochondrial membrane is interrupted; Synthesis of ATP is increased when the pH of the intermembrane space is lowered relative to the pH of the mitochondrial matrix

Question 33

Allopurinol

Answer 33

Analog of hypoxanthine (which causes competitive inhibition) and an inhibitor of xanthine oxidase, and as such, is used to alleviate the elevated urate concentration associated with gout

Question 34

Cancer cells sometimes have normal ATP levels, despite having defective mito.

Answer 34

Best explained if cells incapable of aerobic respiration respond by increasing the rate of glycolysis

Question 35

Glucose and AA are:

Answer 35

Transported by sodium-dependent co-transport not fat

Question 36

Electron carriers in the ETC

Answer 36

Cytochrome c, ubiquinone, and FADH2

Question 37

What would limit the rate of electron flow through the ETC?

Answer 37

The formation of a proton gradient across the inner mitochondrial membrane

Question 38

ATP hydrolysis accompanies the production of which intermediate of glycolysis

Answer 38

Fructose 1,6-bisphosphate

Question 39

GI tract bacteria

Answer 39

Convert monosaccharides and polysaccharides into acetate, propionate, and butyrate, which are short chain fatty acids

Question 40

Membrane transporter is electrogenic and translocates a net charge across the membrane

Answer 40

Na+-glucose transporter; electrogenic, as it results in the net movement of positively charged molecules into the cell.

Question 41

Which enzyme is not directly involved in generation of the dinucleotide required for Na+-NQR activity?

Answer 41

Succinate dehydrogenase; does not require NAD+/NADH

Question 42

Which type of rxn has a Keq > 1 and is kinetically fast?

Answer 42

Exergonic with low activation energy level

Question 43

Which type of rxn has a Keq > 1 and is kinetically fast?

Answer 43

Exergonic with low activation energy level

Question 44

Inactive form

Answer 44

GAP catalyzes the conversion of Arf1-bound GTP to GDP and inorganic phosphate, thereby converting Arf1 to the inactive form; therefore hydrolysis of the phosphate of GTP bound to Arf1 results in its inactivation

Question 45

Fatty acid head

Answer 45

Consists of a carboxyl group