Bbmb 316 Exam 4

Front 1

In going from acetyl-CoA to succinate, two carbons have entered the citric acid cycle and two carbons have been released as CO2. Why is the cycle not considered complete at this point?

Back 1

The oxaloacetate used to initiate the cycle must be regenerated.

Front 2

How would the concentration of citric acid intermediates be affected by the administration of a drug that inhibits succinyl dehydrogenase activity?

Back 2

Succinate levels would increase.

Front 3

As shown below, identify the step in the citric acid cycle that requires a molecule of inorganic phosphate:

Back 3

the reaction catalyzed by succinyl-CoA synthetase

Front 4

Intermediates of the citric acid cycle are shown below. What class(es) of biochemical reactions is(are) depicted?

Back 4

2 lyase reactions

Front 5

Which molecule initiates the citric acid cycle by reacting with oxaloacetate?

Back 5

acetyl CoA

Front 6

In bacteria, ATP is an allosteric inhibitor of the Citric Acid Cycle enzyme citrate synthase. The KM of citrate synthase for acetyl CoA increases in the presence of ATP. As the level of ATP increases:

Back 6

less citrate synthase reacts with acetyl CoA

Front 7

Which two citric acid cycle enzymes are allosterically inhibited by ATP?

Back 7

isocitrate dehydrogenase and α-ketoglutarate dehydrogenase

Front 8

What is the chief benefit of being able to perform the glyoxylate cycle?

Back 8

it enables plants and microorganisms to convert fats, through acetyl CoA, into glucose

Front 9

The purpose of anaplerotic reactions is:

Back 9

to replenish the citric acid cycle if it becomes depleted of intermediates by biosynthetic demands.

Front 10

The glyoxylate cycle enables plants to survive using only:

Back 10

acetate

Front 11

It has been noted that the mitochondria of muscle cells often have more cristae than the mitochondria of liver cells. Which of the following is(are) correct?

Back 11

A. During exercise, the ATP needs of muscle will excede those of the liver.

B. Additional oxidative phosphorylation sites can be provided by an increase in mitochondrial cristae.

Front 12

Oxidative phosphorylation in mitochondria is often monitored by measuring oxygen consumption. You are given a suspension of isolated mitochondria and directed to add citrate, ADP and Pi. Predict the effect on oxygen concentration [O2].

Back 12

Oxygen concentration [O2] will fall because citrate is a fuel and ATP can be formed from ADP and Pi.

Front 13

In oxidation-reduction reactions, electrons need to be shuttled from one molecule to another. Which of the following statements is true?

Back 13

Electrons are added to NAD+, which then carries the electrons to another electron acceptor.

Front 14

Electron flow down the electron transport chain leads to:

Back 14

the transport of protons across the inner mitochondrial membrane from inside the matrix to the intermembrane space.

Front 15

What is a cytochrome?

Back 15

a protein that transfers electrons and that also contains a heme group.

Front 16

What type of gradient is critical to ATP formation by oxidative phosphorylation?

Back 16

proton

Front 17

What is the chemical effect of rotenone on aerobic respiration?

Back 17

The flow of electrons from NADH to CoQ is blocked.

Front 18

An arginine residue (Arg 210) in the matrix-side proton channel of the a subunit of ATP synthase is near the aspartate residue (Asp 61) in the c ring subunit. How might Arg 210 assist proton flow?

Back 18

Arg 210, with its positive charge, will facilitate the release of a proton from Asp 61 by stabilizing the negative charge of its acidic side chain.

Front 19

Based on your knowledge of regulation of metabolic pathways, which of the following would you expect to occur as ADP levels rise in the mitochondria?

Back 19

ATP synthase activity would increase

Front 20

Which of the following would most likely occur if the mitochondrial inner membrane was freely permeable to small ions?

Back 20

Electron transport would be uncoupled from ATP synthesis

Front 21

The activated electrons from photosystem I lead to:

Back 21

reduction of NADP+ and helps to form a proton gradient.

Front 22

Photosynthesis can be measured by determining the rate of oxygen production. In your first experiment testing photosynthetic rates, you expose plants to light with a wavelength of 680 nm and find that they produce more oxygen compared with plants exposed to light at 700 nm. Correctly explain your observations.

Back 22

The reaction center of photosystem II absorbs light maximally at 680 nm, and photosystem II powers oxygen release.

Front 23

Which mechanism is the method by which antenna complex chlorophylls transfer energy toward reaction centers?

Back 23

resonance energy transfer

Front 24

Identify the light dependent changes in the stroma that regulate the Calvin cycle:

Back 24

increase in NADPH concentration

increase in the concentration of reduced-ferredoxin

increase in Mg2+ concentration

increase in pH

Front 25

What is the source of carbons for the Calvin Cycle?

Back 25

carbon dioxide

Front 26

Rubisco is found in:

Back 26

in the stroma of the chloroplasts

Front 27

In the Calvin cycle, reducing power is provided by:

Back 27

NADPH

Front 28

In C3 plants the conservation of water promotes:

Back 28

photorespiration

Front 29

Which hormone(s) are signals for glycogen breakdown?

Back 29

epinephrine and glucagon

Front 30

The major site(s) of glycogen storage is (are):

Back 30

b) liver

c) skeletal muscle

Front 31

The process by which a bond is cleaved by the addition of orthophosphate is:

Back 31

phosphorolysis

Front 32

The enzyme that serves as the glucose "sensor" in liver cells:

Back 32

phosphorylase a

Front 33

Which of the following is NOT required for the synthesis of a glycogen particle starting from glucose 6-phosphate?

Back 33

glycogen phosphorylase

Front 34

After exercise, muscle cell glycogen metabolism is regulated by:

Back 34

protein phosphatase 1

Front 35

α-1,6-glycosidic bonds are created by:

Back 35

branching enzyme

Front 36

At the center of a glycogen molecule is:

Back 36

glycogenin

Front 37

The oxidative phase of the pentose phosphate pathway produces:

Back 37

NADPH

Front 38

In the nonoxidative stage of the pentose phosphate pathway, intermediates of which pathway(s) is/are produced?

Back 38

glycolysis

Front 39

Which biosynthetic pathway(s) requires NADPH?

Back 39

cholesterol

fatty acid

nucleotide

Front 40

The function of the pentose phosphate pathway is to:

Back 40

B) generate NADPH

C) generate carbon chain sugars that are intermediates in glycolysis, gluconeogenesis and other biosynthetic pathways