Test 21 - Biochem Flashcards Preview

UWorld > Test 21 - Biochem > Flashcards

Flashcards in Test 21 - Biochem Deck (23)
Loading flashcards...
0

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

1385

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

1

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

1021

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

2

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

1021

Wernicke's Encephalopathy due to increased thiamine demand

3

How does Wernicke's encephalopathy present?

1021

1) Ataxia
2) Acute confusion
3) Opthalmoplegia

4

Which bacterial replication machinery removes RNA primers?

1471

DNA Polymerase 1

5

Which B vitamin is Thiamine?

1047

B1

6

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

1249

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

7

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

1023

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

8

What is Pantothenic Acid? What is it involved in?

1044

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

9

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

1034

Acetyl-CoA

10

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

1386

Protons and CO2 (called the Bohr effect)

11

Niacin is derived from which amino acid?
1064

Tryptophan

12

A deficiency of Niacin results in what?

1064

Pellegra

Characterized by:
1) Dermatitis
2) Dementia
3) Diarrhea

13

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

Alpha-ketoglutarate, causing inhibition of the Krebbs cycle.

14

Excess ammonia depletes which Neurotransmitter?

8578

Glutamate

and causes accumulation of glutamine causing astrocyte swelling and dysfunction.

15

Tea and Toast diet refers to which vitamin deficiency?

1247

Vitamin C

16

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

1030

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

Debranching enzyme (Alpha-1,6-glucosidase)

17

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

997

Pyruvate -> ocaloacetate
Pyruvate carboxylase

FA: 104

18

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

997

Phosphoenolpyruvate
Phosphenolpyruvate carboxykinase

19

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

997

Gluconeogenesis

20

The pyruvate dehydrogenase complex requires which 5 cofactors?

1033

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

FA: 102

21

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

Aldose Reductase

22

Breast milk is devoid of which vitamins?

1926

Vitamin D and K