Broad Overview of Metabolism

Question 1

What metabolic functions are performed in the liver during the fed state?

Answer 1

Glucose is used as the main energy source. Excess glucose is converted to glycogen or acetyl CoA for triacylglycerol storage.

Question 2

What is the main energy source in the liver during prolonged fasting/starvation?

Answer 2

Fatty acids

Question 3

What tissues or organs maintain energy stores?

Answer 3

Liver & adipose tissue

Question 4

What metabolic functions are performed in the muscles during the basal state?

Answer 4

Muscles use glycogen, fatty acids, and ketone bodies for energy. Proteins are broken down to amino acids for glucose production in the liver if fasting persists.

Question 5

What organ, tissue, or cell only uses glucose for energy?

Answer 5

RBCs - lack mitochondria

Question 6

What is the main energy source in the brain during prolonged fasting/starvation?

Answer 6

Ketone bodies

Question 7

What is the main source of energy in the brain and muscles during the fed state?

Answer 7

Glucose. Excess glucose in muscles is stored as glycogen.

Question 8

What is the role of O2 and CO2 in metabolism?

Answer 8

O2 is necessary to produce ATP. Energy production releases CO2.

Question 9

What is the difference between catabolism and metabolism?

Answer 9

Catabolism is the breakdown of complex molecules that releases energy. Anabolism is the synthesis of molecules from smaller units and requires ATP.

Question 10

What molecules link the metabolic pathways?

Answer 10

Glucose-6-phosphate, pyruvate, acetyl-CoA

Question 11

What are the forms of chemical energy?

Answer 11

ATP, NADH, NADPH

Question 12

How does the body efficiently drive endergonic reactions forward?

Answer 12

The body couples endergonic reactions with exergonic reactions that release energy driving the endergonic reaction forward. The overall delta G of both reactions is negative.

Question 13

How does the liver maintain glucose levels during the basal state?

Answer 13

Glucose is released through glycolysis and glycogenolysis. When stores are depleted, the liver initiates gluconeogenesis and generates ketone bodies from fatty acids.

The main energy source changes from glucose to fatty acids.

Question 14

True/False. A larger negative delta G indicates a quicker reaction.

Answer 14

False. Reaction speed is determined by the enzymes catalyzing the reaction and NOT delta G.

Question 15

What are the seven major metabolic pathways?

Answer 15

Glycolysis, gluconeogenesis, glycogen metabolism, fatty acid metabolism, TCA, oxidative phosphorylation, amino acid metabolism

Question 16

What are the differences between exergonic and endergonic reactions?

Answer 16

Exergonic reactions release energy and are energetically favorable with negative delta G. Keq > 1

Endergonic reactions are energetically unfavorable, with a positive delta G, and require input of energy to proceed. Keq < 1

Question 17

What is the role of O2 and H2O in metabolism?

Answer 17

Oxygen serves as the final electron acceptor in the electron transport chain to produce ATP. H2O is produced in the process.

Question 18

What is the main energy source for the brain during the basal state?

Answer 18

Glucose

Question 19

How long does it take glucose levels to return to normal after eating?

Answer 19

Approximately 2 hours

Question 20

What is the normal glucose range in a healthy adult?

Answer 20

80-100 mg/dL