Test 4

Question 1

Where do Gluceogenesis occur in humans?

Answer 1

Liver
Kidneys
Small Intestines

Question 2

Purpose of Glucose

Answer 2

• used for energy storage

- serves as a precursor for 5 carbons sugars (ribose and deoxyribose) used in nucleic acids

Question 3

Describe the transport mechanism to bring lactate from the muscle to the liver

Answer 3

since the muscle does not carry out gluceoneogenesis

• lactate is transported out of the muscle, through the blood, and transported into the liver where it can be used in gluceoneogenesis
• process called the cori cycle

Question 4

Cori Cycle

Answer 4

• synthesis of glucose in the liver
• transfer of glucose to muscle where it is used for ATP
• Transport of lactate back to liver where it is used for gluceoneogenesis

Question 5

Where doe the regulatory enzyme ATP work?

Answer 5

inhibits glycolysis at the enzyme PFK-1 and Pyruvate Kinsae

Question 6

Where doe the regulatory enzyme Citrate work?

Answer 6

inhibits glycolysis at the enzyme PFK-1

Question 7

Where does the regulatory enzyme AMP work?

Answer 7

activates glycolysis at the enzyme PFK-1

inhibits gluceoneogenesis at the enzyme Fructose 1,6-phosphatase

Question 8

Where does the regulatory enzyme Fructose 1,6-bisphosphate work?

Answer 8

activates glycolysis at the enzyme Pyruvate Kinase

-feed forward activation

Question 9

Where does the regulatory enzyme Acetyl-CoA work?

Answer 9

activates gluceoneogenesis at the enzyme pyruvate carboxylase

Question 10

What is a very important allosteric regulatory in Glycolysis and gluceogenesis?

Answer 10

Fructose 2,6-bisphosphate

• induces the glycolysis pathway by activating PFK-1
• at the same time it suppresses the gluceogenesis pathway by inhibiting the enzyme fructose 1,6-bisphosphatase

Question 11

PKA involvement in gluceogenesis and glycolysis

Answer 11

-the enzyme pyruvate kinase is inhibited by phosphorylation carried out by the kinase PKA

Question 12

Glycogen synthesis

Answer 12

-occurs in the liver, kidney, and small intestine

Steps:
Glucose
Glucose 6-phosphate
Glucose 1-phosphate
UDP glucose

The UDP glucose is then synthesized by the glycogen synthase to make glycogen

Question 13

Glycogen degradation

Answer 13

glycogen is reacted with Pi by the enzyme polysaccharide phosphorylase to produce glucose 1-phosphate

Question 14

Glucagon

Answer 14

secreted by the pancreas in response to low blood glucose levels
-role is to induce gluconeogenesis

Question 15

How does Glucagon induce gluceogenesis?

Answer 15

binds to receptors in the liver that activate cAMP synthase

-cAMP synthase activates PKA

Question 16

PKA

Answer 16

• phosphorylates pyruvate kinase and inhibits it, inhibiting the last step of glycolysis
• results in phosphorylation of glycogen phosphorylase-activating it- which results in synthesis of Glucose 1-phosphate from glycogen
• phosphorylates glycogen synthase which it inhibits it and no more glycogen is made

Question 17

Insulin

Answer 17

-activates phosphoprotein phosphatase-1

Question 18

Liver cells and glucagon

Answer 18

glucagon raises glucose concentration by producing glucose from glycogen and blocking glycogen resynthesis

Question 19

Liver cells and insulin

Answer 19

insulin lowers glucose concentration by activating glycogen synthesis and blocking glycogen phosphorolysis

Question 20

Why do other cells not have an effect on glucagon

Answer 20

these cells do not have glucagon receptors.

Instead muscle, adipocytes, and the heart respond to epinephrine to raise glucose concentration

Question 21

What does the Pentose phosphate pathway result in?

Answer 21

• results in the biosynthesis of ribose 5-phosphate for nucleic acids and other 5-carbon sugars from glucose
• also results in two reduced coenzymes (NADPH)