EXAM3_L30_Glycolysis

Question 1

What 2 things in the LIVER serves as the glucose sensor for insulin release?

Answer 1

1. GLUT2 beta cell glucose sensor

2. Glucokinase

Question 2

Where is energy invested in glycolysis?

Answer 2

Step 1 (hexokinase) one atp
Step 3 (PFK-1) one atp

Question 3

Where is energy generation phase of glycolysis?

Answer 3

Step 6 (2 NADH) Glycerol-3PDH
Step 7 (2 ATP) Phosphoglycerate
Step 10 (2 ATP) Pyruvate Kinase

Question 4

Anaerobic glycolysis occurs in cells with no/few mitochondria. What are the reactants and products?

(RBC, Lens, Kidney medulla)

Answer 4

Glucose + 2 ADP + 2Pi > 2 Lactate + 2ATP

Question 5

GLUT 1,2,3,4 transporters
describe 1,3
describe 2
describe 4

Answer 5

1 & 3 have high affinity for glucose & found in most cells
Glut2 beta cell glucose sensor of insulin (liver & Pancreas)
Glut4 (Muscle & adipose) - needs insulin signal

Question 6

What irreversible steps in glycolysis? what enzyme each?

Answer 6

1,3,10

1- hexokinase
3- PFK1
10- Pyruvate Kinase

Question 7

What enzyme used for lactate?

Answer 7

Lactate dehydrogenase (not regulatory)- goes both ways

Question 8

Glucokinase vs Hexokinase

Answer 8

Glucokinase high Vmax/Km - liver pancreas

Hexokinase Low Vmax/Km- most cells

Question 9

Permanent neonatal diabetes mellitus (PNDM)

aka: defective glucose sensing mechanism

Answer 9

Mutation of NO glucokinase

• No C peptide detected
• Develop Hyperglycemia, diabetic ketoacidosis, retardation

Question 10

PFK1- Allosteric regulated
Activated by?
Inhibited by?

Answer 10

Activated by AMP + Fructose 2,6-Bisphosphate

Inhibited by ATP + Citrate in the Cytosol

• means too much and was exported the mitochondria into the cytosol (needs to slow it down)

Question 11

AMP and fructose2,6bisP do what?

Answer 11

Activate PFK1 in glycolysis

Question 12

High levels of ATP and Citrate in the cytosol do what?

Answer 12

Inhibit PFK1 in glycolysis

Question 13

High IG ratio causes decreased cAMP and thus decreases PKA activity

When PKA activity is low what is the effect on PFK2/FBP2 complex?

Answer 13

PFK2/FBP2 complex becomes DEphosphorylated

PFK2 is activated and forms F2,6-BisP

F2,6-BisP:
ACTIVATES: (PFK-1) and thus GLYCOLYSIS and
INHIBITS: (FBPase-1) and thus GLUCONEOGENESIS

Question 14

How does High IG ratio stimulate glycolysis?

3 steps

Answer 14

1. High IG inhibits cAMP and PFK.
2. PFK2/FBP2 complex dephosphorylated» Active PFK2
3. Forms F2,6-BisP: Activates PFK1 (glycolysis)
   Inhibits FBPase1 (gluconeogenesis)

Question 15

How does high IG affect Pyruvate Kinase?

Answer 15

INSULIN DEPHOSPHORYLATES TARGET ENZYMES:

• F1,6BisP dephosphorylated (now ACTIVE) and activates Pyruvate Kinase

Question 16

How does Low IG affect Pyruvate Kinase?

Answer 16

GLUCAGON PHOSPHORYLATES TARGET ENZYMES:

GalphaS-GPCR> cAMP > increased PKA activity (aka phosphorylation)

F1,6BisP inhibited by phosphorylation & Pyruvate kinase inactive

Question 17

Step 11 converts Lactate via LDH (Anaerobic Glycolysis)

What happens?

Answer 17

Pyruvate is reduced by NADH to Lactate in the cytosol
and regenerates NAD+

(remember we need 700:1 NAD+) to continue glycolysis

Question 18

Why is regenerating NAD+ so vital to glycolysis?

Answer 18

NAD+ required for step 6 and for glycolysis to continue

Question 19

Step 11 is called anaerobic glycolysis. What is converted?

Answer 19

Pyruvate is converted to LACTATE by LD
- Regenerates NAD+ (for step 6)

(NAD+ Critical for glycolysis to continue)

Question 20

Lactic acidosis occurs when circulatory Hypoxia

(mi, pe, hemorrhage etc. ) Why?

Answer 20

increased AMP > Activates PFK1> Glycolysis > Lactic Acid

Question 21

DHAP (dihydroxyacetone-P) Used in Liver and adipose tissue for TAG synthesis- what enzyme ? what does it turn into?

Answer 21

G3PDH- makes glycerol 3 phosphate (backbone for TAG)

part of glycerol-3P shuttle ? idk what that means?

Question 22

What are the two steps that generate ATP by Substrate level phosphorylation?

What enzymes do they use?

Answer 22

Step 7 (1,3-BPG)
Step 10 (PEP)

These are High energy intermediates used to make ATP

Question 23

What 2 enzymes produces ATP in glycolysis?

Answer 23

1. Phosphoglycerate Kinase
2. Pyruvate Kinase
   Phosglycerate Kinase= 1,3-BPG (substrate Level Phosphor)
   Pyruvate Kinase= PEP (substrate Level Phosphorylation)

Question 24

What are the glycolytic end products ?

Answer 24

ATP (via phosphoglycerate kinase & pyruvate kinase)
(sublevPhos- 1,3BPG & PEP)
PYRUVATE
NADH (Glyceraldehyde3PDH req. Pi +NAD+)

Question 25

In step 6 NADH is generated by what enzyme? and what are the required substrates?

Answer 25

Glyceraldehyde-3 Phosphate Dehydrogenase (G3PDH)

requires Pi & NAD+

Question 26

In AEROBIC how is NAD+ regenerated from NADH?

What two Ways? Where do they occur?

Answer 26

1. Glycerol-3P Shuttle (NADH > FADH2 inner mito memb)

2. Malate-Aspartate shuttle (NADH>NADH IM-matrix)

Question 27

Pyruvate is pumped into the inner mitochondrial matrix by what type of Transport?

Answer 27

Secondary Active Transport using H+ gradient from ETC

Question 28

Pyruvate + CoA + NAD+ are converted to what?

Answer 28

Acetyl CoA + NADH + H+ +CO2

Question 29

What is PDHC inhibited by?

Answer 29

Products: NADH (ETC overload or low oxygen) + Acetyl CoA (TCA backed up)

Question 30

5 Coenzymes of PDHC and their required Vitamin Precursors?

Answer 30

TPP- thiamine B1
FAD- riboflavin B2
NAD+ Niacin B3
CoA- Pantothenate B5
Lipoic Acid (None)