LECTURE 12

Question 1

What is the source of ATP for almost all eukaryotic organisms?

Answer 1

Cellular respiration

Question 2

Do almost all organism metabolize glucose ?

Answer 2

YES

Question 3

Where does glycolysis occur ?

Answer 3

Cytosol

Question 4

Where does the kerbs cycle ?

Answer 4

Mitochondria

Question 5

Where does fermentation occur ?

Answer 5

Cytosol

Question 6

Glycolysis

Answer 6

1 glucose —-> 2 pyruvate + 2 NADH

Question 7

The 2 ways for further metabolism of pyruvate

Answer 7

1) kerbs cycle and electron transport chain

2) fermentation

Question 8

Kerbs cycle / citric acid cycle

Answer 8

Uses O2 as a final electron acceptor

• called aerobic respiration (needs O2)

Question 9

Fermentation

Answer 9

• converts pyruvate to waste products (ethanol or lactic acid)
• different pathways in different organisms
• does NOT use O2 or an electron transport chain.

Question 10

What accounts for most of ATP synthesis

Answer 10

Oxidative phosphorylation (OXPHOS)

Question 11

Where does OXPHOS occur?

Answer 11

Mitochondria

Question 12

2 phases of glycolysis

Answer 12

1) investment phase

2) energy payoff phase

Question 13

Steps for energy investment (5) in glycolysis

Answer 13

1) hex Okinawa enzyme transfers phosphate to ATP. Makes glucose more reactive
2) glucose-6-phosphate is converted to its isomer fructose-6-phosphate.
3) phosphofructokinase transfers a phosphate to ATP to the opposite end of the sugar (requires a second ATP)
4) adolescences cleaves the 6-carbon sugar into these two 3-C sugars

5) isomerase causes a flip between these two isoforms, the direction on the concentration of reactants.
Glyceralhyde 3-phosphate is rapidly used up, so the equilibrium shifts to favour conversion in that direction.

Question 14

Steps for energy payoff (5) in glycolysis

Answer 14

1) this enzyme catalyzes two couples reactions
A) each G3P is oxidized by transferring 2 e- to NAD+ (exergonic)
B) a phosphate bond is a made, producing a product with very high potential E (endergonic)

2) phosphate added in step 1 is transfers to ADP (exergonic) = substrate level phosphorylation
3) this enzyme changes the location of the phosphate

4) enolase creates a double bond and removes H2O
- PEP contains very high potential E.

5) pyruvate kinase creates ATP via substrate level phosphorylation

Question 15

The two reactions couples in step one of energy payoff in glycolysis

Answer 15

A) each G3P is oxidized by transferring 2 e- to NAD+ (exergonic)

B) a phosphate bond is a made, producing a product with very high potential E (endergonic)

Question 16

4 mains points of glycolysis

Answer 16

• 10 reactions
• occurs in cytoplasm
• anaerobic (No oxygen required)
• occurs in all domains of life

Question 17

NET products of glycolysis

Answer 17

2 molecules of ATP

2 molecules of pyruvate
(3-C =0.5 of glucose)

2 molecules of NADH

Question 18

In eukaryotic cells in the presence of O2 …

Answer 18

Pyruvate enters the mitochondrion where oxidation of glucose is completed

Question 19

Before krebs can begin, pyruvate must be

Answer 19

Converted to acetyl coenzyme (acetyl CoA)

This links glycolysis to Krebs cycle

Question 20

What is the acetyl CoA made of ?

Answer 20

Acetyl group

Ribose

Adenine

Question 21

What is CoA a derivative of and what’s its role ?

Answer 21

Vitamin B

It’s troll if in transferring one molecules (or party of one molecule) to another

Question 22

Oxidation of acetyl CoA

Answer 22

Pyruvate enters into mitochondria

A multi-enzyme complex (pyruvate dehydrogenase complex) then catalyzes these 3 reactions :

1) pyruvate’s carboxyl group already oxidized and contains little E - its removed
2) the remaining 2-C molecules is oxidized; the electrons are transferred to NAD+
3) coenzyme A is attached via its sulfur atom to acetyl group, forming acetyl CoA (has high potential E)

Question 23

In oxidation fo pyruvate to acetyl CoA, Pyruvates entry into the mitochondria requires

Answer 23

Active transport