Krebs Cycle, Oxidative Phosphorylation

Question 1

pH layers of the mitochondria

Answer 1

pH of mitochondrial matrix (9) > pH of cytosol (8) > pH of the intermembrane space (5)

Question 2

superoxide dismutase

Answer 2

an enzyme used to neutralize oxygen radicals, used by the body to induce cell death and destroy invading pathogens

Question 3

reactive oxygen species

Answer 3

a common cause of apoptosis and cellular damage

Question 4

1 molecules of acetyl CoA yields…

Answer 4

1 ATP, 3 NADH, 1 FADH2

= 10 ATP total

Question 5

protons per NADH, FADH2

Answer 5

10 protons per NADH, 6 protons per FADH2 (1 ATP per 4 protons)

these are electron shuttles

Question 6

steps of aerobic CR

Answer 6

1. Glycolysis
2. Pyruvate oxidation
3. Krebs cycle
4. Electron transport chain

(the complete degradation of glucose)

Question 7

purpose of the citric acid cycle (Krebs cycle)

Answer 7

• to reduce NAD+ and FAD
  reactants: CoA, pyruvate
  products: NADH, ATP, acetyl CoA

Question 8

ATP synthase

Answer 8

pumps hydrogen ions into the intermembrane space during electron transport chain

Question 9

ATP per NADH, FADH2

Answer 9

2-3 ATP per NADH, 1-2 per FADH2

Question 10

Electron Transport Chain (reactants, products)

Answer 10

reactants: ADP, oxygen, NADH
products: ATP, NAD+

Question 11

inorganic phosphate

Answer 11

exists in the mitochondrial matrix, which decreases as ATP synthase produces ATP

Question 12

proton pumps

Answer 12

complex IV and III are proton pumps, so they change the pH of the intermembrane space. complex II does not change the pH

Question 13

glucose oxidation (3 steps)

Answer 13

1. glycolysis
2. citric acid cycle
3. oxidative phosphorylation

Question 14

CR final electron acceptors

Answer 14

NADH, FADH2

NADPH is used in photosynthesis

Question 15

where is water formed?

Answer 15

in the mitochondrial matrix

? water continues to be formed if the membrane is permeable to hydrogen protons

Question 16

chemiosmosis

Answer 16

moves hydrogen protons into the mitochondrial matrix, while electron transport chain pumps protons into the intermembrane space

Question 17

oxygen

Answer 17

the final electron acceptor, CN interferes with complex IV so oxygen will not be reduced

Question 18

where does glycolysis occur?

Answer 18

cytosol.

• produces 2 pyruvate (3-carbon), which is broken down into a 2-carbon molecule called Acetyl CoA. one carbon leaves to produce CO2
• produces a net of 2 ATP (generates 4 and uses 2) and 2 NADH

Question 19

citric acid cycle

Answer 19

starts with acetyl CoA (processed glucose), which is broken down to form intermediates useful for OP

Question 20

oxidative phosphorylation

Answer 20

occurs AFTER citric acid cycle; leads to the formation of ATP

Question 21

oxaloacetate

Answer 21

the intermediate of the citric acid cycle, which combines with Acetyl CoA to form citric acid (citrate; 6-carbon) which is oxidized back to oxaloacetate after releasing two CO2 molecules

Question 22

products of CAC

Answer 22

1. GTP (from GDP)
2. 3 NADH and 1 NADH from pyruvate oxidation, and 1 NADH from glycolysis
3. 1 FADH
4. 2 CO2
5. regenerated oxaloacetate
   (6. 1 ATP)

Question 23

“prep step” for Krebs

Answer 23

think of it as pyruvate oxidation:

pyruvate is converted into Acetyl CoA via pyruvate dehydrogenase, with a reduction of one NAD+ to NADH, and 1 CO2 is released

an irreversible step

Question 24

allosteric activators/inhibitors of CAC

Answer 24

activators: ADP, CoA, NAD+, pyruvate, AMP, Ca2+
inhibitors: acetyl CoA, NADH, ATP, fatty acids

free calcium is produced when muscles are using energy

if we have enough fatty acids, it’s a signal we can slow this process down

• there is no hormonal control of this cycle

Question 25

fatty acids can/can’t be converted into acetyl CoA

Answer 25

can. but because pyruvate dehydrogenation is irreversible, fatty acids cannot be converted into glucose because this step is irreversible

Question 26

OIL RIG

Answer 26

oxidation is losing electrons, reduction is gaining electrons

Question 27

where does CAC take place?

Answer 27

inside the mitochondrial matrix

Question 28

total ATP produced from 1 molecule of glucose

Answer 28

~30-32 ATP

Question 29

describe the electron transport chain

Answer 29

complex I takes electrons from NADH while complex II takes electrons from FADH2

NADH is #1, FADH2 is #2

electrons are sent to Ubiquinone, or Q, which are sent to complex III, then Cytochrome C, then complex IV, then oxygen is the final electron acceptor

this “pumps” hydrogens into the inner membrane space

Question 30

the major substrate activator of ETC

Answer 30

ADP!

Question 31

what happens in apoptosis

Answer 31

the permeability of the mitochondria increases, and Cytochrome C leaks out

Question 32

CR totals (write out by memory!)

Answer 32

glycolysis: 2 ATP, 2 NADH
pyruvate oxidation: 2 NADH
krebs/CAC: 2 ATP, 6 NADH, 2 FADH2