Glycolysis / Carbohydrate Metabolism

Question 1

What is the overall reaction of glycolysis?

Answer 1

Coverting 1 glucose -> 2 pyruvates and generating 2 ATP

Question 2

What are the two phases of glycolysis?

Answer 2

1. Investment Phase (invest ATP)
2. Payoff Phase (produce ATP)

Question 3

What is a kinase?

Answer 3

enzyme that catalyzes a phosphorlyation reaction using a molecule of ATP as the phsphoryl donor

Question 4

What is an isomerase?

Answer 4

an enzyme that catalyzes a rearrangement of the atoms in a molecule

Question 5

What is the difference between a phosphoryl group and a phosphate group?

Answer 5

phosphoryl = PO₃^2-
phosphate = PO₄^3-

Question 6

What input is required for the preparation phase of glycolysis?

Answer 6

2 ATP

Question 7

What are hte net products of glycolysis?

Answer 7

2 NADH
2 ATP
2H₂O

4 ATP are made by glycolysis but 2 are septn in teh preparation phase

Question 8

What does hexokinase do?

Answer 8

It is the enzyme for the 1st step of glycolysis (activation of glucose).
Transfers a phosphate from ATP on to carbon 6.
Starting molecule: glucose (6 carbons)
Post reaction molecule: glucose-6-phosphate

Reaction requires ATP (ATP ->ADP)

Question 9

What effect does production of glucose-6-phosphate hvae on glycolysis?

Answer 9

Glucose-6-phosphate allosterically inhibits hexokinase.

example of negative feedback regulation. allosteric: binding to enzyme’s allosteric site leading to confomraitonal cahnge and inhibition of enzyme activity

Question 10

What is the 2nd step of glycolysis?

Answer 10

Glucose-6-phosphate (6 ring) goes through isomerization to form fructose-6-phosphate (5 ring)

Question 11

What is the role of phosphofructokinase (PFK-1)?

Answer 11

Adds a phosphoryl group to fructose-6-phosphate to form fructose-1,6 - bisphosphate.
Reaction requires ATP b/c it takes the phosphoryl group from ATP.
F-1,6-BP = highest energy level

Question 12

Increased 2,6-bisphosphate stimulates phosphofructokinase-1 (PFK-1) (the taste limiting enzyme of glycolysis)

Answer 12

True

Question 13

What is the Cori Cycle?

Answer 13

When oxygen supply is insufficient, typically during intense muscular activity, energy must be released through anaerobic metabolism. The Cori cycle refers to the process of transporting lactate from cells that are undergoing anaerobic metabolism to the liver where it is used to provide glucose back to the cells.

Pyruvate can be converted to lactate by lactate dehydrogenase, and lactate can then travel to the liver. Because this is a reversible reaction, lactate can be reconverted back to pyruvate in the liver by lactate dehydrogenase as well. Within the liver, pyruvate can enter gluconeogenesis and help form a new glucose molecule. Glucose can then enter the circulation and go back to the muscle cell, where it can be broken down in glycolysis to make ATP and, once again, pyruvate. This cycle is called the Cori cycle.

Question 14

Why can’t muscles participate in gluconeogenesis?

Answer 14

because they lack glucose-6-phosphatase