Ch 12 Fat&Carb Metabolism

Question 1

What is the role of coenzyme A in carbohydrate and fat metabolism?

Answer 1

To shuttle the carbons from the metabolism of glucose and fatty acids into the Krebs Cycle.

Question 2

What is NAD+ and its role in metabolism

Answer 2

One of the principal redox carriers. Nicotinamide Adenine Dinucleotide (NAD+), when reduced, gains a hydrogen and becomes NADH. This hydrogen is carried to the electron transport chain.

Question 3

Is NAD+ or NADH the more energized molecule

Answer 3

NADH has an increased electron count, so there is an increase in potential energy.

Question 4

What sugar is in ATP

Answer 4

ribose.

Question 5

Three mechanisms for ATP generation

Answer 5

1. Substrate-level phosphorylation
   (Transferring high-energy phosphate group from an intermediate directly to ADP)
2. Oxidative phosphorylation (cellular respiration) - Remove electrons and pass them through electron transport chain to oxygen
3. Photophosphorylation
   * Only in chlorophyll-containing plant cells

Question 6

Is glucose oxidized or reduced to create energy?

Answer 6

Oxidized. Breaking the carbon-oxygen double bonds.

Question 7

What are the 4 steps of glucose oxidation?

Answer 7

1. glycolysis
2. pyruvate
3. krebs cycle
4. electron transport chain

Question 8

Glucose oxidation produces about how many ATPs?

Answer 8

about 32 ATPs

Question 9

From glycolysis alone, what is produced?

Answer 9

2 pyruvic acid molecules (both go into kreb cycle), 2 molecules ATP, 2molecules NADH

Question 10

Where does glycolysis occur?

Answer 10

In the cytosol

Question 11

In aerobic metabolism, the pyruvic acid is transported where to continue energy production? Is this passive or active transport?

Answer 11

transported from the cytosol into the mitochondrial matrix
* (active transport mechanism, so requires energy).

Question 12

pyruvate is converted to _____? Then enters the _____?

Answer 12

In the presence of oxygen and coenzyme A (CoA), pyruvate is
converted to acetyl-CoA. Which then goes into Kreb cycle.

Question 13

So, what enters the CAC at the end of glycolysis into the mitochondrial matrix?

Answer 13

1 NADH, CO2, and Acetyl-CoA

(remember this happens twice because 2 pyruvate molecules are formed from glycolysis and go to mitochondria)

Question 14

Kreb cycle has how many reactions

Answer 14

8 enzyme driven reactions

Question 15

What are the products of one acetyl-CoA molecule entering the Kreb cycle?

Answer 15

Oxidation of each molecule of acetyl-CoA produces two CO2, one ATP, three NADH, and one QH2 molecule.

Question 16

What happens to the NADH and QH2 that is produced from the Kreb cycle?

Answer 16

The NADH and QH2 feed into the electron transport chain.

Question 17

Where is the electron transport chain located

Answer 17

Inner mitochondria membrane

Question 18

How do NADH and QH2 release their energy to transform ADP to ATP?

Answer 18

Using oxygen as the electron acceptor, the reduced NADH and QH2 are oxidized (give-up the e-) and the oxygen is reduced (accepts the e-) to water. The energy released during those redox reactions is used to phosphorylate ADP to ATP

Question 19

Each NADH produces how many ATP?

Answer 19

2.5

Question 20

Under anaerobic conditions, pyruvate is converted to?

Answer 20

Lactic Acid. This reaction requires NADH, so much less efficient energy production

Question 21

Each QH2 produces how many ATP?

Answer 21

1.5

Question 22

Each Acetyl CoA produces how many ATP

Answer 22

10

Question 23

The overall efficiency of ATP production from carbohydrates is what percent effect and what percent lost as heat?

Answer 23

• 43% EFFICIENT
• 57% LOST AS HEAT (most enzymatic processes function in narrow physiologic windows of heat and pH, so there’s that)

Question 24

The acetyl portion, broken from a fatty acid chain or glucose, is bonded to coenzyme A through what functional group?

Answer 24

A thioester functional group. O=C-S

Question 25

the role of coenzyme A

Answer 25

To shuttle the carbons from the metabolism of glucose and fatty acids into the Krebs Cycle.