Major Energy Molecules and Cellular Metabolism

Question 1

List the 4 main categories of biomolecules.

Answer 1

Carbohydrate, Proteins, Lipids, Nucleic Acid

Question 2

Compare the entry points of glucogenic versus ketogenic amino acid carbon skeleton for catabolism

Answer 2

Glucogenic AA - converted into a-keto acid and enters as pyruvate, a-ketoglutarate, Succinyl CoA, Fumarate

Ketogenic AA - degraded into Acetyl CoA which is then converted to ketone bodies and moved to liver

Question 3

Contrast the roles of glycolysis and gluconeogenesis

Answer 3

Glycolysis - use glucose to form 2 pyruvate molecules, 2 ATP, and 2 NADH (catabolic)

Gluconeogenesis - occurs in liver and regenerates glucose via circumventing irreversable rxns (anabolic)

Question 4

Propose why fatty acids cannot be a source for gluconeogenesis

Answer 4

Fatty acids are degraded to Acetyl CoA which are then converted to ketone bodies

Question 5

Describe the shuttling of ketone bodies from liver to skeletal muscle during times of fasting or exercise

Answer 5

Ketone bodies are converted to Acetyl CoA which is then fed to Kreb Cycle

Question 6

Describe the shuttling of lactate between skeletal muscle and liver during anaerobic exercise

Answer 6

produced in the muscles when regenerating NAD+ for glycosylation. Lactate is transported to the liever where it is converted to pyruvate and regenerated as glucose

Question 7

Describe the shuttling of alanine between skeletal muscle and liver during anaerobic exercise

Answer 7

Pyruvate is converted to alanine when a NH4+ group is added to it during the production of a-keto acid in muscles. Alanine is then transported to the liver where it is converted back to pyruvate after giving NH4+ to a-ketoglutarate

Question 8

Describe the shuttling of glutamine between skeletal muscle and liver during anaerobic exercise

Answer 8

Glutamine is formed when glutarate takes a NH4+ group in muscle. It then goes to the liever where it releases NH4+ to the urea cycle and becomes glutamine again.

Question 9

Describe the shuttling of glucose between skeletal muscle and liver during anaerobic exercise

Answer 9

Glycogen is broken down to glucose in the liver which is then transported to muscle where it is broken down in glycolysis and the Kreb cycle