Review 2: TCA Cycle

Question 1

Through what process are triglycerides converted into acetyl coA?

Answer 1

beta oxidation of fatty acids

Question 2

What can acetyl CoA go on to become?

Answer 2

1) energy via TCA
2) ketone bodies
3) fatty acids; cholesterol

Question 3

What 3 things can produce acetyl coA?

Answer 3

1) pyruvate
2) fatty acids
3) amino acids

Question 4

What enzyme is responsible for converting pyruvate into acetyl CoA?

Answer 4

PDH (pyruvate dehydrogenase)

Question 5

What 3 vitamin cofactors are required for PDH function?

Answer 5

1) Thiamine (B1)
2) Riboflavin (B2)
3) Niacin (B3)

Question 6

The most common form of pyruvate dehydrogenase deficiency is caused by mutations in the ___ alpha gene (X-linked)

Answer 6

E1

Question 7

Children with PDH deficiency have elevated serum levels of ________, _______, and ________.

Answer 7

lactate, pyruvate, and alanine

cannot shuttle pyruvate into TCA cycle

Question 8

Each cycle of the TCA generates ___ ATP and ___ GTP

Answer 8

9; 1

reoxidation of 3 NADH, 1 FADH2, and 1 GTP

Question 9

What is the ATP conversion rate of reoxidizing NADH? FADH2?

Answer 9

NADH 2.5

FADH2 1.5

Question 10

What method of enzyme regulation is primarily responsible for the fine control of TCA enzymes?

Answer 10

allosteric regulation

Question 11

higher conc of ADP and Ca++ __________ TCA cycle

Answer 11

stimulates

Question 12

higher conc of ATP, GTP, and NADH (high energy) _______ TCA cycle.

Answer 12

inhibits

Question 13

True or False: TCA cycle intermediates can be replenished by anaplerotic (intermediate) reactions

Answer 13

True

Question 14

Aspartate can feed into the TCA cycle as what?

Answer 14

oxaloacetate

Question 15

glutamate can feed into the TCA cycle as what?

Answer 15

alpha ketoglutarate

Question 16

propionyl coA (from valine and isoleucine) can feed into the TCA cycle as what?

Answer 16

succinyl CoA

Question 17

Aspartate, phenylalanine, tyrosine can feed into the TCA cycle as what?

Answer 17

fumarate

Question 18

Define gluconeogenesis

Answer 18

synthesis of glucose from noncarbohydrate precursors

Question 19

What condition stimulates gluconeogenesis?

Answer 19

low blood glucose

Question 20

Where does gluconeogenesis take place?

Answer 20

liver and kidney

Question 21

During gluconeogenesis, pyruvate is converted into ___________________

Answer 21

phosphoenolpyruvate (in a 2 step process via oxaloacetate) this is the ACTIVATED form of pyruvate

Question 22

What two substances are involved in the activation of pyruvate into PEP?

Answer 22

bicarbonate and cofactor biotin

Question 23

What is the Cori Cycle?

Answer 23

glucose-lactate cycle

Question 24

Where does the Cori cycle occur?

Answer 24

RBCs and skeletal muscle

Question 25

Where does the Alanine cycle occur?

Answer 25

skeletal muscle

Question 26

Does gluconeogeneis produce or consume ATP?

Answer 26

CONSUME

Question 27

True or false: gluconeogenesis from amino acids requires more ATP (which is used for ureagenesis)

Answer 27

true

Question 28

What serves as the major source of ATP for gluconeogenesis during fasting?

Answer 28

Oxidation of fatty acids

Question 29

What are the 4 enzymes that are required to reverse the 3 irreversible steps of glycolysis?

Answer 29

1) pyruvate carboxylase (in the mitochondria)
2) Phosphoenolpyruvate carboxykinase (cytoplasm)
3) Fructose 1,6 bisphosphatase (cytoplasm)
4) Glucose 6-phosphatase (cytoplasm)

Question 30

The lack of which enzyme causes the accumulation of pyruvate in the plasma (which is then converted to lactate)

Answer 30

Pyruvate carboxylase

Question 31

What reaction does pyruvate carboxylase catalyze?

Answer 31

pyruvate to oxaloacetate

Question 32

What is von Gierke disease?

Answer 32

deficiency of glucose 6-phosphatase

inherited autosomal recessive - glycogen storage disease

Question 33

What reaction cannot happen in patients with von Gierke disease?

Answer 33

gluconeogenesis (glucose 6-phosphatase cannot convert glucose 6-phophate into glucose for the brain to use)

Question 34

What happens to the liver in patients with von Gierke disease?

Answer 34

enlarges due to the accumulation of glycogen and fat in the liver (elevated serum uric acid and lactate)

Question 35

Ethanol metabolism can cause ___________ because high NADH OPPOSES gluconeogenesis

Answer 35

hypoglycemia

Question 36

Ethanol metabolism ___________ the NADH/NAD ratio

Answer 36

increases

Question 37

high levels of NADH promotes the conversion of pyruvate and oxaloacetate into ________ and _______

Answer 37

lactate and malate

Question 38

Increased NADH leads to lactate _______

Answer 38

formation

Question 39

decreased NADH leads to _______ lactate formation

Answer 39

decreased