Glycolysis 2

Question 1

Glycolysis

Answer 1

Breakdown of glucose monomer

Question 2

Gluconeogenesis

Answer 2

Synthesizing glucose from scratch; used when the supply of glycogen is exhausted

Question 3

Pentoses

Answer 3

5-c sugars generated in the Pentose phosphate pathway

Question 4

What happens to free energy when it is released or consumed?

Answer 4

It is transferred to carriers like ATP and NADH

Question 5

What is the rate of pathway flux controlled by?

Answer 5

Changing activity of individual enzymes

Question 6

Steps 1-5 of glycolysis are known as

Answer 6

(Glucose to G-3-P) Energy investment phase because it requires 2 ATPs

Question 7

Steps 6-10 of glycolysis are known as

Answer 7

G-3-P to pyruvate; energy payoff phase because they yield 4 ATP (net yield 2 ATP)

Question 8

What three pathways are irreversible (have negative delta G values)?

Answer 8

1, 3, 10; flux control points that slow down the rxn

Question 9

What is the direction controlled by in the reversible steps?

Answer 9

by the concentration of substrates and products (mass action ratio)

Question 10

Where does regulation of the pathway occur

Answer 10

Step 3; irreversible ; flux control point / rate determining step

Question 11

Regulation of PFK in bacteria

Answer 11

Regulated by allosteric effectors

Question 12

What is the allosteric activator of PFK in bacteria?

Answer 12

ADP; increase in ADP means need more ATP therefore turn on pathway

Question 13

What is the allosteric inhibitor of PFK in bacteria?

Answer 13

PEP; as PEP increases, too much product so much shut down pathway; ALSO ATP

Question 14

What is PEP

Answer 14

Phosphoenolpyruvate

Question 15

Regulation of PFK in Mammals

Answer 15

Fructose-2,6P2 is an activator

Question 16

How does Fructose-2,6-bisphosphate get involved

Answer 16

When blood glucose is high, insulin is produced to process the glucose; Insulin stimulates PFK-2 to make Fructose-2,6-bisphosphate which then activates PFK-1(makes FBP in step 3) to send more glucose to be processed by glycolysis

Question 17

F26BP is an allosteric activator of

Answer 17

PFK1

Question 18

F26BP is an allosteric inhibitor of what

Answer 18

FBPase-1

Question 19

Why is step 1 and 10 not a control point?

Answer 19

Because they can be bypassed

Question 20

What are the 4 other fates of pyruvate

Answer 20

1. acetyl CoA (aerobic, kreb)
2. Oxaloacetate
3. Lactate (anaerobic)
4. Ethanol + CO2 (yeast)

Question 21

Pyruvate to oxaloacetate

Answer 21

Add CO2

Question 22

Pyruvate to Acetyl-CoA

Answer 22

Remove CO2

Question 23

Pyruvate to lactate

Answer 23

NADH + H+ to NAD+; reduced through lactate dehydrogenase (ANAEROBIC METABOLISM)

Question 24

Pyruvate to Ethanol

Answer 24

NADH to NAD+

Question 25

Where does the NAD+ produced from lactate

Answer 25

To be recycled back into GAPDH rxn in step 6 to continue glycolysis

Question 26

What is the benefit of making lactate from pyruvate

Answer 26

Keeps metabolism moving without needing more ATP

Question 27

What type of pathway is gluconeogenesis?

Answer 27

Anabolic pathway; costs energy and does not operate in the cell

Question 28

Reversal of glycolysis

Answer 28

Conversion of 2 Pyruvates to 1 glucose

Question 29

Gluconeogenesis cost vs glycolysis yield

Answer 29

Gluconeogenesis costs: 4 ATP, 2 GTP and 2 NADH Glycolysis yields: 2 ATP and 2 NADH

Question 30

First step of storing glucose

Answer 30

Glucose-6-phosphate is converted to glucose-1-phosphate by phosphoglucose-mutase

Question 31

Second step of storing glucose

Answer 31

G-1-P is activated by UTP to make UDP-glucose and PP; PP (G= -33.5) is used to drive the rxn forward; (UDP glucose formation is irreversible)

Question 32

Third step of glycogen storage

Answer 32

Glycogen synthase links glucose units via alpha(1-4) and UDP functions as a leaving group

Question 33

How are the branch points in glycogen created?

Answer 33

Glycogen-branching enzyme moves 7 resides from the main chain to form a new branch

Question 34

Debranching enzyme to remove glucose in glycogen

Answer 34

A cleaving enzyme moves 3 residues to the main chain and then cleaves the alpha 1-6 branch point to release glucose

Question 35

How is stored glucose released

Answer 35

After phosphorylation yield G-1-P, Mutase converts it to G-6-P and phosphatase removes phosphate to make just glucose

Question 36

Why is G6P converted to glucose

Answer 36

Phosphorylated sugars cannot cross the plasma membrane

Question 37

What is the significance of ribose-5-phosphate

Answer 37

Sugar base to make all the nucleotide’s needed to form DNA and RNA

Question 38

Path 1 of PPP

Answer 38

Oxidative path; irreversible

Question 39

What does path 1 produce?

Answer 39

NADPH and ribulose-5-phosphate which may be reversibly converted to ribose-5-phosphate

Question 40

Path 2 of the PPP

Answer 40

The carbon rearrangement path

Question 41

What happens in path 2

Answer 41

2 F6P and one GAPare rearranged through a series of reversible reactions to Ru5P

Question 42

Path 3 of the PPP

Answer 42

When the cell needs NADPH but not ribose; G6P is converted to Ru5P which is converted to GAP and f6P by reversing the carbon rearrangement path

Question 43

What can NADPH be used for in the PPP?

Answer 43

To reduce ribose-5-phosphate to deoxyribose-5-phosphate