CH9 Carbohydrate Metabolism

Question 1

Glucose Transport

Glut 2 vs Glut 4 (location, Km)

Answer 1

Glut 2: Liver, pancreas, is not responsive to insulin but a glucose sensor which causes the release of insulin

Glut 4: In Adipose tissue, and muscle. It responds to insulin. They can become saturated. Low Km = high affinity

Question 2

Glycolysis

• Hexokinase, and Glucokinase
• Phosphofructokinase (PFK1 and PFK2)
• Glyceraldehyde-3-phosphate Dehydrogenase
• Pyruvate Kinase

Irreversible Steps:

Hexokinase, glucokinase, PFK1, Pyruvate kinase

Answer 2

• Hexokinase: Converts glucose to glucose 6-phosphate. and is inhibited by its product (negative feedback)
• Phosphofructokinase: rate-limiting enzyme. fructose 6-phosphate is phosphorylated to fructose 1,6-biphosphate using ATP. Is inhibited by ATP and Citrate, and activate by AMP
• Glyceraldehyde-3-phosphate Dehydrogenase: catalyzes oxidation and addition of phosphate to its substrate and forms 1,3-biphosphoglycerate and reduction of NAD to NADH.
• Pyruvate Kinase: makes Pyruvate in glycolysis

Question 3

Fermentation

• lactate dehydrogenase

Answer 3

• lactate dehydrogenase: oxidizes NADH to NAD

Question 4

Enzyme in the Citric Acid Cycle:

Pyruvate dehydrogenase what does it form?

what does dehydrogenase mean?

Answer 4

Pyruvate dehydrogenase forms acetyl CoA

by-products are CO2 and NADH

Any dehydrogenase promotes the oxidation of NAD+ to NADH

Succinate Dehydrogenase oxidases FADH₂

Question 5

Important Enzymes in:

• Glycogenesis: glycogen synthase (rate-limiting step)
• Glycogenolysis: glycogen phosphorylase
• Gluconeogenesis: pyruvate carboxylase

Answer 5

• Glycogenesis: glycogen synthase forms the alpha- 1, 4 glycosidic bonds to form a straight chain, 1,6 to put a branch
• Glycogenolysis: glycogen phosphorylase breaks the 1,4 bonds , it can not break 1,6 bonds
• Gluconeogensis: The first step in gluconeogenesis is carboxylation of pyruvate to form oxaloacetate by pyruvate carboxylase

Question 6

PPP what does it do

what does NADPH do

Answer 6

source of ribose 5-phosphate for nucleotide synthesis and NADPH

NADPH = helps prevent oxidative damage, is an electron donor, it is oxidized so it is a reducing agent

helps in biosynthesis of fatty acids and cholesterol

Question 7

Please, Can I keep Selling Sex For Money, Office?

Answer 7

Pyruvate

Citrate

Isocitrate

Ketoglutarate (alpha)

Succinyl-CoA

Succinate

Fumarte

Malate Oxaloacetate

Question 8

Citric Acid Cycle net of by-products

Answer 8

2CO_{2 ,} CoA-SH, 3NADH, 3H+ , FADH2, GTP

Question 9

What complexes do the following:

• Pumping proton into the intermembrane space:
• Acquiring electrons form NADH:
• Acquiring Electrons from FADH₂:
• Having the highest reduction potential:
  *

Answer 9

• Pumping proton into the intermembrane space: 1, 3, and 4
• Acquiring Electrons from NADH: 1
• Acquiring Electrons from FADH₂: 2
• Having the highest reduction potential: 4

reduction potential increases along the ETC

Question 10

Uses of ATP:

• ATP Hydrolysis
• ATP Cleavage

Answer 10

• ATP Hydrolysis: give energy to a reaction from the hydrolysis of ATP
• ATP Cleavage: transfer a high energy phosphate group from ATP to another molecules, to activate or inactivate