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Flashcards in Biochemistry- Carbohydrates Deck (73)
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1

What 2 monosaccharides make up lactose?

glucose and galactose

2

What 2 monosaccharides make up sucrose?

glucose and fructose

3

Which polysaccharide is comprised of glucose units linked by 1,4 alpha bonds?

amylose

4

What polysaccharide has glucose linked at 1,4 and 1,6 linkages?

glycogen

5

what polysaccharide has long chains of 1,4 linkages and every 25 molecules has a 1,6 branch?

Amylopectin

6

What polysaccharide has glucose molecules bound at beta 1,4 linkages?

cellulose (we can't digest it! = fiber)

7

Which disaccharide has two glucose units?

Maltose

8

Sailvary amylase cleaves what type of bond?

alpha 1,4

9

maltase cleaves which linkage?

alpha 1,6

10

The enzymes maltase, sucrase, dextrine and lactase are found where?

brush border of mucosal cells

11

what is the rate limiting enzyme in the reaction of fructose to glucose?

fructokinase

12

What is the rate limiting enzyme in the reaction of galactose to glucose?

galactokinase

13

Dextrin is only released from the hydrolysis of which polysaccharide?

amylopectin

14

What hormone is released when glucose levels are high?

insulin

15

Which organ keeps a constant level of glucose in the blood by storing and producing it as needed?

the liver

16

Which organ does not require insulin to take up glucose?

the liver

17

Which hormone is released when glucose levels are down?

glucagon

18

Which of the catecholamines stimulates gluconeogenesis?

epinephrine

19

Glucokinase is only found in which organ?

the liver

20

in what part of the cell does glycolysis occur?

cytosol

21

What enzyme allows the liver to trap glucose in the form of glucose-6-phosphate?

glucokinase (hexokinase in other tissues)

22

What are 3 rate limiting enzymes of glycolysis?

gluco/hexokinase, phosphofructokinase, pyruvate kinase,

23

How many molecules of pyruvate do we get from one molecule of glucose?

2

24

What mineral is required for the phosphorylation reactions of glucokinase, hexokinase and phosphofructokinase?

Magnesium

25

What is the net ATP gained from aerobic glycolysis?

8 ATP (-2 ATP, +6 ATP from 2 NADH, +4ATP)

26

Which Krebs cycle intermediate inhibits action of phosphofructokinase and therefore inhibits glycolysis?

citrate

27

What is the aerobic fate of pyruvate?

Acetyl-CoA

28

Under anaerobic conditions pyruvate if reduced into:

Lactate

29

What enzyme complex converts pyruvate into Acetyl-CoA?

Pyruvate dehydrogenase complex

30

What vitamins are needed for the pyruvate dehydrogenase complex?

B1 (thiamin)
B2 (FAD)
B3 (NAD)
B5 Pantothenic acid

31

What mineral is required for the pyruvate dehydrogenase complex?

Magnesium

32

Pyruvate carboxylase converts pyruvate into what?

oxaloacetate

33

What cofactor is important in the carboxylation reaction of pyruvate to oxaloacetate?

Biotin

34

Why is the production of oxaloacetate from pyruvate important?

starts the Krebs cycle

35

What acts to promote pyruvate dehydrogenase and the subsequent formation of Acetyl-CoA?

The presence of pyruvate

36

What inhibits pyruvate dehydrogenase and promotes pyruvate carboxylase, thus shuttling pyruvate into oxaloacetate?

The presence of Acetyl-CoA

37

Where does the Krebs cycle take place?

In the mitochondria

38

Which metabolite of the Krebs cycle is used for fatty acid synthesis?

Citrate

39

Which 2 Krebs cycle metabolites are important for amino acid synthesis?

oxaloacetate and alpha keto-glutarate

40

Which krebs cycle metabolite is used in porphyrin/heme metabolism?

succinyl-CoA

41

Acetyl-CoA joins with what substance to form citrate?

oxaloacetate

42

What regulates the Kreb cycle?

ratio of ADP to ATP

43

What does high levels of ATP do to the Krebs cycle?

slows it down

44

What coenzymes are needed in the Krebs cycle?

B3- NAD
B2- FAD
B5 to make succinyl CoA

45

Name 4 uses for Acetyl CoA

ATP production, Fatty Acid synthesis, Ketone synthesis, Cholesterol formation

46

Which enzyme regulates the levels of Acetyl CoA?

Pyruvate dehydrogenase complex

47

What are 3 ways that the body can produce acetyl CoA?

1. from pyruvate
2. via beta oxidation of fatty acids
3. alanine-->pyruvate, or from citrate

48

What are the 2 reducing equivalents?

NAD and FAD

49

What metabolite of the Krebs cycle is an important indicator of energy status of the cell?

Citrate

50

How is oxaloacetate transported out of the mitochondrion?

via converstion to malate (malate shuttle)

51

In what organs does the gluconeogenesis occur?

liver, sometime kidney

52

Which hormone, by its involvement with glucagon, inhibits glycolysis and promotes gluconeogenesis?

Epinephrine

53

What steroid hormone promotes the gluconeogenic pathway?

Cortisol

54

name 3 substrates for gluconeogenesis

1. alanine
2. glycerol
3. lactate

55

What affect do fructose 1,6 diphosphate and 2,6 diphosphate have on gluconeogenesis?

inhibit it, by inhibiting fructose 1,6- diphosphotase

56

What are 2 products of the hexose monophosphate shunt?

NADPH, Ribose

57

What is the net output of the Krebs cycle?

3 NADH, 1 FADH, 1 GTP

58

What is the key rate limiting enzyme in glycogen synthesis?

glycogen synthase

59

What cytokine activates glycogen synthase?

insulin

60

What hormones inhibit glycogen synthase?

cortisol, glucagon

61

What substance in low quantities inhibits glycogen synthase?

cAMP

62

Which tissues have high amount of glycogen?

liver and skeletal muscle

63

Which metabolite in glycolysis is transformed into glycogen?

glucose-6-phosphate

64

What substance carries glucose molecules to the growing glycogen chain?

UDP

65

What is the rate-limiting enzyme in glycogenolysis?

phosphorylase

66

How is NADPH used in the body?

maintains Fe in RBCs

67

How many ATP molecules do you get from NADH?

3

68

How many ATP molecules do you get from 1 FADH?

2

69

Where does FADH enter the electron transport chain?

ubiquinone

70

What mineral is important in the electron transport chain?

Fe

71

What is the overall net energy output from 1 molecule of glucose?

8 ATP from glycolysis
2 NADH from pyruvate to acetyl CoA --> 6 ATP
6 NADH --> 18 ATP
2 FADH -->4 ATP
2 GTP--> 2 ATP
Total 36-38 ATP

72

What is the final electron acceptor in the electron transport chain?

oxygen

73

The process of forming ATP from electrons is called what?

Transduction