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Flashcards in Biochem Deck (76):
1

Desmin stain

Muscle

2

Cytoskeleton stain

Epithelial cells

3

Gfap

Neuro glia

4

Neurofilaments

Neurons

5

I cell disease

Deficient mannose-6-phosphate

6

Which way do Dynein and kinesin move?

Dynein moves retrograde (+ to -) and kinesin moves anterograde (- to +)

7

What does ouabain do?

Inhibits the na/k pump by binding to the K+ site

8

Where does hydroxyl action of collagen occur?

In the RER, specific proline and lysine residues are hydroxylated. Requires vitamin c (deficiency causes scurvy)

9

Where does glycosylation and the forming of collagen triple helices occur

In the RER. Problems firming this helix lead to osteogenesis imperfect a

10

What is Menkes disease?

X linked recessive connective tissue disease caused by impaired copper absorption and transport due to defective Menkes protein. Leads to decrease activity of Lysol oxidase

11

What is RNA interference?

DsRNA is synthesized that is complementary to the mRNA sequence of interest. When transfected into human cells, dsRNA separates and promotes degradation of target mRNA, "knocking down" gene expression

12

What is special about the inheritance of alpha-1 anti trypsin deficiency

The alleles are co-dominant

13

What is heteroplasmy?

Presence of both normal and mutated mtDNA, resulting in variable expression in mitochondria lily inherited disease

14

Vimentin stain

Connective tissue

15

Enzymes that use thiamine

Pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase, transketolase, branched-chain ketoacid dehydrogenase

16

Reactions vitamin B2 is used in

(Riboflavin) Used as cofactors in redox reactions, eg, the succinate dehydrogenase reaction in the TCA cycle

17

How is niacin made?

Derived from tryptophan. Requires B2 and B6.

18

How can you get a deficiency of niacin?

Hartnup disease (decreased tryptophan absorption), malignant carcinoid syndrome (increased tryptophan metabolism), and isoniazid (decreased vitamin B6)

19

What reactions is B5 needed for?

(Pantothenic acid) Essential component of coenzyme A (CoA, a cofactor for acyl transfers) and fatty acid synthase

20

What is B6 used for?

Converted to pyridoxal phosphate (PLP), a cofactor used in transamination (eg. ALT and AST), decarboxylation reactions, glycogen phosphorylase. Synthesis of cystathionine, heme, niacin, histamin, and neurotransmitters including serotonin, epi, norepi, dopamine, and GABA

21

What is B7 used for?

(Biotin) Cofactor for carboxylation enzymes: pyruvate carboxylase, acetyl-CoA carboxylase, propionyl-CoA carboxylase

22

How can you get a deficiency of biotin?

Antibiotic use or excessive digestion of raw egg whites.

23

What reaction is B12 needed for?

Homocysteine to Methionine (homocysteine methyltransferase) and Methylmalonyl-CoA to Succinyl-CoA (methylmalonyl-CoA mutase [isomerase])

24

Interaction between Vitamin C and iron

Vitamin C facilitates iron absorption by reducing it to Fe2+ state

25

What is Vitamin C necessary for?

Hydroxylation of proline and lysine in collagen synthesis; necessary for dopamine beta-hydroxylate, which converts dopamine to NE

26

Rosary chest

Rickets (vitamin D deficiency in children)

27

Type of anemia in vitamin E deficiency

Hemolytic

28

Lab values in vitamin K deficiency

Increased PT and aPTT but normal bleeding time

29

Zinc deficiency

Delayed wound healing, hypogonadism, decreased adult hair, dygeusia, anosmia, acrodermatits enteropathica. May predispose to alcoholic cirrhosis

30

Liver findings in kwashiorkor

Fatty change due to decreased apolipoprotein synthesis

31

Ethanol metabolism

Ethanol to acetaldehyde by alcohol dehydrogenase (in the cytosol); then acetaldehyde to acetate be acetaldehyde dehydrogenase (in the mitochondria)

32

What is fomepizole

Inhibits alcohol dehydrogenase and is an antidote for methanol or ethylene glycol poisoning

33

What is disulfiram

Inhibits acetaldehyde dehydrogenase

34

What is the limiting reagent in ethanol metabolism

NAD+

35

What changes does ethanol metabolism cause?

Increases the NADH/NAD ratio in the liver, causing: pyruvate to go to lactate, oxaloacetate to go to malate (preventing gluconeogenesis-> fasting hypoglycemia), and dihydroxyacetone phosphate to of to glycerol-3-phosphate (combines with fatty acids to make triglycerides causing hepatosteatosis). NADH/NAD ratio also disfavors TCA production of NADH causing increased utilization of acetyl-CoA for ketogenesis and lipogenesis

36

Ethanol can be metabolized in the peroxisome by what enzyme?

Catalase

37

Ethanol can be metabolized in the microsome by what enzyme?

CYP2E1 (creates ROS)

38

What regulates glycogen synthase?

Positive regulation: glucose-6-phosphate, insulin, and cortisol; negative regulation: epinephrine and glucagon

39

What regulates the HMP shunt

Positive: NADP+, Negative: NADPH

40

What regulates glycolysis?

Positive: AMP, fructose-2-bisphosphate, Negative: ATP, citrate

41

What regulates gluconeogenesis?

Positive: ATP, acetyl-CoA; Negative: AMP, fructose-2,6-bisphosphate

42

What regulates fatty acid synthesis?

Positive: insulin, citrate; negative: glucagon, palmitoyl-CoA

43

What regulates fatty acid oxidation?

Negative: Malonyl-CoA

44

Effect of arsenic on glycolysis

Causes it to produce zero net ATP

45

When are NAD+ and NADPH used?

NAD+ is used in catabolic process to carry reducing equivalents away as NADH; NADPH is used in anabolic processes as a supply of reducing equivalents

46

Hexokinase vs glucokinase

Hexokinase- most tissues, low Km (higher affinity), low Vmax (lower capacity), not induced by insulin; glucokinase- liver and beta cells of pancreas, higher Km (lower affinity), high Vmax (higher capacity), induced by insulin

47

Vomiting, rice-water stools, garlic breath

Arsenic poisoning (arsenic inhibits lipoic acid)

48

How many ATP are produced per NADH/ FADH2

1NADH=2.5 ATP, 1 FADH2 = 1.5 ATP

49

What does Rotenone block

Complex 1 of the electron transport chain

50

What does antimycin A block

Complex III of the electron transport chain

51

What does oligomycin block?

Complex V of the electron transport chain. An ATP synthase inhibitor. Directly inhibits mitochondrial ATP synthase, causing an increased proton gradient. No ATP is produced because electron transport stops

52

What blocks complex IV?

Cyanide, CO

53

Irreversible enzymes of gluconeogenesis

Pyruvate carboxylase, phosphoenolpyruvate carboxykinase, fructose-1,6-bisphosphatase, glucose-6-phosphatase

54

What does pyruvate carboxylase require? What activates it?

Biotin, ATP. Activated by acetyl-CoA

55

What does PEP CK require?

GTP

56

What regulates fructose-1,6-bisphosphatase?

Pos: citrate; neg: fructose-2,6-bisphosphate

57

What is NADPH required for?

Glutathione reduction inside RBCs, fatty acid and cholesterol biosynthesis

58

Where does the HMP shunt take place?

Lactating mammary glands, liver, adrenal cortex (sites of fatty acid or steroid synthesis), RBCs

59

What is a copper reaction test?

Nonspecifically detects the presence of reducing sugar

60

Genetics of essential fructosuria

Autosomal recessive, involves a defect in fructokinase

61

Fructose intolerance

Autosomal recessive, deficiency of aldolase B. Fructose-1-P accumulates causing a decrease in available phosphate which results in inhibition of glycogenolysis and gluconeogenesis.

62

Treatment of fructose intolerance

Decrease intake of both fructose and SUCROSE (glucose + fructose)

63

What may present as a failure to track objects or to develop a social smile?

Galactokinase deficiency, galactitol accumlates, causing cataracts. Autosomal recessive

64

FTT, jaundice, hepatomegaly, infantile cataracts, intellectual disability. Can lead to E. coli sepsis in neonates

Classic galactosemia, absence of galactose-1-phosphate uridyltransferase, AR

65

Tx of galactosemia

Exclude galactose and lactose (galactose and glucose) from the diet

66

Which cells have only aldose reductase?

Schwann cells, retina, and kidneys

67

What is an alternative method of trapping glucose in the cell?

Converting it to its alcohol counterpart, sorbitol, via aldose reductase (requires NADPH)

68

What happens to sorbitol?

Some tissues (liver, ovaries, and seminal vesicles) have sorbitol dehydrogenase (requires NAD+) that can convert it to fructose

69

Diagnosing lactase deficiency

Stool demonstrates decreased pH and breath shows increased hydrogen content with lactose tolerance test. Intestinal biopsy shows NORMAL mucosa

70

Which amino acids are acidic?

Aspartic acid and glutamic acid

71

Which amino acids are basic?

Arginine, lysine, histidine

72

Treatment of pyruvate dehydrogenase complex deficiency?

Increase intake of ketogenic nutrients (e.g., high fate content or increased lysine and leucine)

73

What are the essential amino acids?

Methionine, valine, histidine (glucogenic). Isoleucine, phenylalanine, threonine, tryptophan (glutogenic/ketogenic). Leucine, lysine (ketogenic)

74

Urea cycle

CO2+NH3 goes to carbamoyl phosphate in the rate limiting step. (Required cofactor: N-acetylglutamate) Then carbamoyl phosphate combines with ornithine to make citrulline. Citrulline + aspartate = argininosuccinate. Fumarate leaves-> arginine. Organize converts this to urea and ornithine

75

What is the Cori cycle?

Glucose to pyruvate to lactate (moves to liver) to pyruvate to glucose (moves to tissue)

76

What is the Cahill cycle?

Glucose in the muscle to pyruvate to alanine (moves to liver) to pyruvate back to glucose (moves to muscle)