Other Stuff to Know

Question 1

What are the two mobile electron carriers of the ETC?

Answer 1

• Coenzyme Q10

- Cytochrome C

Question 2

At which complex do protons combine with O2 to produce H2O in the ETC?

Answer 2

Complex IV

Question 3

In adipose tissue, what is the main fate of dietary glucose? What pathway does this occur in and what is the enzyme utilized?

Answer 3

Production of glycerol phosphate

Occurs in lipogenesis and requires GPDH

Question 4

In fed state, which process produces pyruvate and what are its fates?

Answer 4

In fed state, pyruvate is produced by glycolysis and it can be converted to either Acetyl CoA or OAA (both are made into citrate for lipogenesis)

Question 5

In fasting state, what produces pyruvate and what is its fate?

Answer 5

In fasting state, pyruvate is produced by lactate or AAs and it can only be converted to OAA for gluconeogenesis

Question 6

What is the enzyme of Lipolysis and how is it regulated? (hint: think fed v fasting)

Answer 6

HSL is the rate-limiting enzyme of Lipolysis
+: phosphorylation via high epi (NOT GLUCAGON)
-: dephosphorylation via high insulin; Niacin

Question 7

What is the only tissue type where glucagon receptors are found?

Answer 7

LIVER

Question 8

What product from the TCA Cycle can act to increase synthesis of nucleotide precursors utilizing the HMP Shunt? Why?

Answer 8

Citrate because it is an inhibitor of PFK-1, the rate limiting enzyme of glycolysis
- If PFK-1 is inhibited, there will be an accumulation of Glucose 6P (upstream of PFK-1 step) that will be shunted to the HMP Shunt to produce NADPH

Question 9

What tissue cell type is ethanol catabolized in? What parts of the cell are they catabolized, and which are used for acute or chronic exposure?

Answer 9

Cytosol and smooth ER of liver cells

• Cytosol is acute and chronic
• Smooth ER is chronic only

Question 10

What two enzymes are used to catabolize ethanol and in which parts of the cell are they utilized?

Answer 10

• Cytosol: alcohol dehydrogenase and aldehyde dehydrogenase

- Smooth ER: aldehyde dehydrogenase only

Question 11

With increased ethanol intake, what is increased and in what part of the cell? Why?

Answer 11

High ethanol intake = High NADH(cyto)

The reactions of both alcohol dehydrogenase and aldehyde dehydrogenase both produce NADH

Question 12

What are the five enzymes that require coenzymes, and what are those coenzymes?

Answer 12

• PDHC (TPP, riboflavin, niacin, pentothenate)
• alpha-KGDH (TPP, riboflavin, niacin, pentothenate)
• PC (biotin)
• Transketolase (TPP)
• Glycogen Phosphorylase (pyridoxine)

Question 13

If we provide dextrose without Thiamine to an alcoholic, which enzyme will demonstrate increased activity? What is the consequence?

Answer 13

Lactate Dehydrogenase activity would be increased (Pyruvate > Lactate)

This would lead to lactic acidosis

Question 14

What are the three steps of De Novo cholesterol metabolism? Which enzymes are used in the first and second steps?

Answer 14

1. Synthesis of HMG CoA via HMG CoA Synthase(cyto)
2. Synthesis of Mevalonic Acid via HMG CoA Reductase
3. Synthesis of cholesterol

Question 15

In adipose cells, what is LPL used for? What is LPL used for in muscle cells? In what state (fed or fasting) are these actions occurring?

Answer 15

• Adipose cells: LPL used for storage in fed state

- Muscle cells: LPL used for energy in fasting state