Glycolysis/PDH Complex/TCA Cycle

Question 1

How does glucose become “trapped” inside the cell?

Answer 1

Hexokinase and glucokinase use ATP to phosphorylate glucose, and the GLUT transporters only recognize the non-phosphorylated glucose

Question 2

Name the pathway of products through glycolysis

Answer 2

Glucose-> Glucose 6-Phosphate->Fructose 6-Phosphate->Fructose 1, 6-Bisphosphate->Glyceraldehyde 3-Phosphate->1,3-Bisphosphoglcerate->3-Phospholglycerate->2-phosphoglycerate->Phosphoenol Pyruvate->Pyruvate

Question 3

What is the Km of Hexokinase?

Answer 3

Low Km, reaches max velocity at low glucose

Question 4

What is the Km of Glucokinase?

Answer 4

High Km, acts proportionally with blood glucose concentrations

Question 5

What is Hexokinase inhibited by?

Answer 5

Concentrations of Glucose 6-Phosphate

Question 6

What is Glucokinase inhibited by?

Answer 6

Insulin

Question 7

Where is Glucokinase located?

Answer 7

in hepatocytes and Beta-Islet cells

Question 8

What is the rate limiting step/main control point of Glycolysis?

Answer 8

Phosphofuctokinase (PFK1)

Question 9

In hepatocytes, PFK-1 is stimulated by?

Inhibited by?

Answer 9

Stimulated by insulin

Inhibited by Glucagon

Question 10

What is PFK-1 inhibited by in cells other than hepatocytes?

Answer 10

ATP and citrate

Question 11

What does Glyceraldehyde 3-phosphate dehydrogenase do?

Answer 11

Catalyzes oxidation and addition of an inorganic phosphate to Glyceraldehyde 3-phosphate to create high energy intermediate called 1,3-Bisphoglycerate

Question 12

The oxidation and addition of a phosphate to Glyceraldehyde 3-phosphate provides something for Anaerobic metabolism, what is this?

Answer 12

It provides NADH for the reaction of pyruvate to lactate

Question 13

3-phosphoglycerate kinase does what?

Answer 13

Transfers the high energy phosphate from 1,3 Bisphosphoglycerate to ADP, creating ATP and 3-Phosphoglycerate

Question 14

Pyruvate kinase is activated by?

Answer 14

Fructose 1,6 bisphosphate

Question 15

Which enzyme in Glycolysis is an example of feed forward regulation?

Answer 15

Pyruvate kinase

Question 16

Which substrates are responsible for ATP production?

Answer 16

1,3 Bisphosphoglycerate and Phosphoenol pyruvate

Question 17

Name the enzymes of glycolysis in order:

Answer 17

Hexokinase/glucokinase->Isomerase->PFK1->Aldolase->Glyceraldehyde 3-Phosphate Dehydrogenase->Phosphoglycerol Kinase->Mutase->Enolase->Pyruvate kinase

Question 18

What is the Pyruvate Dehydrogenase Complex activated by?

Answer 18

In the liver by insulin

In nervous system-not responsive to hormones

Question 19

The Pyruvate Dehydrogenase Complex is made of 5 enzymes, what are the 3 important ones?

Answer 19

Pyruvate Dehydrogenase
Dihydrolipoyl Transferase
Dihydrolipoyl Dehydrogenase

Question 20

the Pyruvate Dehydrogenase Complex is inhibited by?

Answer 20

Acetyl-Coa

Question 21

Where does glycolysis occur?

Answer 21

in the cytoplasm.

Question 22

Where does the citric acid cycle occur?

Answer 22

in the mitochondria

Question 23

What is the only pathway for ATP production in Erythrocytes?

Answer 23

Glycolysis

Question 24

The difference between cellular glycolysis and glycolysis in erythrocytes is?

Answer 24

An enzyme called bisphosphglycerate mutase, which converts 1,3-Bisphosphoglycerate to 2,3 BPG which binds allosterically with HbA

Question 25

The binding of 2,3 BPG to HbA in RBC’s is?

Answer 25

It allows the unloading of oxygen in tissues while still keeping 100% O2 compacity in the lungs

Question 26

What is the only enzyme of glycolysis that functions under anerobic conditions?

Answer 26

PFK-1