Chapter 12

Question 1

Ranking metabolic process in order of fed state to post fed state

Answer 1

Glycolysis (Fed-state)
Glycogenolysis (right after fed-state)
Gluconeogenesis (12 hours after fed-state, becomes dominant after 24 hours post-fed state)
Fatty Acid Oxidation (occurs simultaneously as gluconeogenesis, but starts to increase after 2-3 days)
Ketogenesis (becomes the main fuel source for most tissues after prolonged starvation)

Question 2

What kind of hormones/enzymes/metabolic processes are active during the fasting state?

Answer 2

Question 3

Which metabolic process contributes directly to gluconeogenesis? Which process is indirect?
fatty acid oxidation or amino acid catabolism

Answer 3

Amino acid catabolism contributes directly, as several amino acids can be converted into pyruvate.
Fatty acid oxidation contributes indirectly because the acetyl-CoA which is the product of FA oxidation stimulates the enzyme pyruvate carboxylase to convert pyruvate –> OAA, but acetyl-CoA doesn’t directly feed into gluconeogenesis.

Question 4

Overview of where all the metabolic processes occur in the cell

Answer 4

Glycogenolysis & Glycogenesis occurs in cytosol

Question 5

True or false:
Amino acid metabolism only make up 10-15% of our total energy production.

Answer 5

True

Question 6

Preferred fuels for different tissues in fed and fasting states

Answer 6

Question 7

What tissues in the body don’t respond to insulin?

Answer 7

Nervous tissue, kidney tubules, RBCs, B-cells of pancreas, intenstinal mucosa

Question 8

What tissues does glucagon act on?

Answer 8

Hepatocytes (liver)

Question 9

How do glucocorticoids control metabolism in the body?

Answer 9

These hormones are released from the adrenal cortex, such as cortisol, known for its response to stress. It elevates blood glucose levels by making more glucose available to the brain while inhibiting glucose uptake in muscle and fat tissue,

Question 10

Where are catecholamines produced and how do they influence our metabolism?

Answer 10

Produced in adrenal medulla, two of them are epinephrine and norepinephrine.
Increase glycogenolysis in liver & muscle
Stimulate hormone sensitive lipase
Increase lipolysis in adipose tissue
Stimulates heart to increase basal metabolic rate

Question 11

How does insulin release affect adipose tissue?

Answer 11

-Stimulates glucose uptake in adipose tissue because a byproduct of glycolysis is glycerol which is needed to make triacylglycerols
-Increases uptake of fatty acids released from lipoproteins

Question 12

Short, high intensity workouts

Answer 12

Depend on glycogenolysis and anaerobic glycolysis

Question 13

Why are fatty acids not used as an energy source for the brain?

Answer 13

They can’t cross the blood brain barrier.

Question 14

Equation for calculating BMI

Answer 14

mass/height^2
mass is in kg
height is in m

Question 15

Calculating respiratory quotient

Answer 15

CO2 produced/O2 produced

Question 16

Comparing how many molecules of NAD+ are consumed to produce 2 acetyl-CoAs each for 1 glucose molecule and 1 B-hydroxybutyrate (from ketone synthesis).

Answer 16

1 glucose = 2 acetyl CoA
Glycolysis yields 1 NAD+, PDH reaction yields 1 NAD+ so 2 NAD+ produced per acetyl-CoA = 4 NAD+ for 2 Acetyl-CoAs

Backwards conversion of the ketone body β-hydroxybutyrate yields 2 acetyl-CoA molecules, but only 1 NAD+ is used

Question 17

Why are gluconeogenesis and liver glycogen degradation favored during stress situations? Describe the release of cortisol, epinephrine and glucagon starting with ACTH.

Answer 17

Stress leads to release of ACTH (adreno-cortico-tropic hormone, it stimulates the adrenal cortex). The adrenal cortex releases cortisol. While cortisol passes by the adrenal medulla, it leads to release of epinephrine (and epinephrine). [cortisol stimulates the methylation of norepinephrine to epinephrine]
*Epinephrine reduces the release of insulin from B-cells and stimulates the release of glucagon from a-cells of the pancreas.
*In the blood are now increased levels of cortisol, epinephrine and glucagon

Question 18

Acetyl-Coa inhibits ______ and activates _______

Answer 18

pyruvate dehydrogenase, pyruvate carboxylase

Question 19

Following lipolysis, glycerol is absorbed by the liver, then phosphorylated by ______ into glycerol phosphate which is then converted into DHAP by __________.
Glycerol is then funneled into what pathways?

Answer 19

glycerol kinase; glycerol 3-P dehydrogenase

Either glycolysis or gluconeogenesis

Question 20

What are the energy requirements of gluconeogenesis to form 1 glucose? Which steps utilize energy (ATP/GTP/NADH)?

Answer 20

2 ATP - conversion of pyruvate to OAA
2 GTP - conversion of OAA to PEP
2 ATP - conversion of 3 BPG to 1,3 BPG
2 NADH - conversion of 1,3 BPG to glyceraldehyde-3-phosphate

Question 21

What are the energy requirements for glycolysis (to produce 2 pyruvates)?

Answer 21

2 ATP (glucokinase/hexokinase) and (PFK-1)
2 NAD

Question 22

In glycolysis, after the step w/ glyceraldehyde 3-phosphate the reactions run twice which is why 4 ATP are produced. Which enzymes produce the ATPs?

Answer 22

phosphoglycerate kinase and pyruvate kinase