Test 21 - Biochem

Question 0

What cofactors are needed for alpha-ketoglutarate dehydrogenase in the TCA cycle?

1021

Answer 0

1) Thiamine
2) CoA
3) Lipoic acid
4) NAD +
5) FAD

Question 1

What causes left shift in oxygen-hemoglobin curve? (3)

1385

Answer 1

1) Decreased H (increased pH)
2) Decreased 2,3-BPG
3) Decreased temperature

Question 2

Administration of glucose to thiamine-deficient patient will result in what?

1021

Answer 2

Wernicke’s Encephalopathy due to increased thiamine demand

Question 3

How does Wernicke’s encephalopathy present?

1021

Answer 3

1) Ataxia
2) Acute confusion
3) Opthalmoplegia

Question 4

Which bacterial replication machinery removes RNA primers?

1471

Answer 4

DNA Polymerase 1

Question 5

Which B vitamin is Thiamine?

1047

Answer 5

B1

Question 6

Elastin’s ability to stretch and recoil is due to what property?

1249

Answer 6

A unique form of desmosine crosslinking between 4 different lysine residues on 4 different elastin chains.

Question 7

What are the signs for Pompe’s Disease? (5)

1023

Answer 7

1) Hepatomegaly
2) Cardiomegaly
3) Macroglossia
4) Hypotonia
5) Mental retardation in the most severe form.

Question 8

What is Pantothenic Acid? What is it involved in?

1044

Answer 8

1) Biologically active form is Coenzyme A

2) Binds with oxaloacetate in 1st step of TCA cycle to form citrate and then succinyl CoA.

Question 9

What is an important allosteric activator of pyruvate carboxylase in gluconeogenesis?

1034

Answer 9

Acetyl-CoA

Question 10

In the lungs, the binding of oxygen to hemoglobin molecules stimulates the release of what?

1386

Answer 10

Protons and CO2 (called the Bohr effect)

Question 11

Niacin is derived from which amino acid?

1064

Answer 11

Tryptophan

Question 12

A deficiency of Niacin results in what?

1064

Answer 12

Pellegra

Characterized by:

1) Dermatitis
2) Dementia
3) Diarrhea

Question 13

Hyperammonemia in hepatic encephalopathy results in the depletion of what?
8578

Answer 13

Alpha-ketoglutarate, causing inhibition of the Krebbs cycle.

Question 14

Excess ammonia depletes which Neurotransmitter?

8578

Answer 14

Glutamate

and causes accumulation of glutamine causing astrocyte swelling and dysfunction.

Question 15

Tea and Toast diet refers to which vitamin deficiency?

1247

Answer 15

Vitamin C

Question 16

Cori’s Disease presents with what signs? Which enzyme is deficient?

1030

Answer 16

1) Hypoglycemia
2) Hypertriglceridemia
3) Ketoacidosis
4) Hepatomegaly

Debranching enzyme (Alpha-1,6-glucosidase)

Question 17

The initial committed step of gluconeogenesis involves conversion of what to what by which enzyme?

997

Answer 17

Pyruvate -> ocaloacetate
Pyruvate carboxylase

FA: 104

Question 18

Oxaloacetate is converted to what in gluconeogenesis? By which enzyme?

997

Answer 18

Phosphoenolpyruvate

Phosphenolpyruvate carboxykinase

Question 19

After 12 to 18 hours of fasting, what is the principle source of glucose?

997

Answer 19

Gluconeogenesis

Question 20

The pyruvate dehydrogenase complex requires which 5 cofactors?

1033

Answer 20

1) Pyrophosphate (B1, thiamine; TPP)
2) FAD (B2, riboflavin)
3) NAD (B3, niacin)
4) CoA (B5, pantothenate)
5) Lipoic acid

FA: 102

Question 21

Galactitol is formed from excess circulating galactose in galactosemia by which enzyme?
1074

Answer 21

Aldose Reductase

Question 22

Breast milk is devoid of which vitamins?

1926

Answer 22

Vitamin D and K