Biochemistry- Carbohydrates Flashcards Preview

NPLEX I > Biochemistry- Carbohydrates > Flashcards

Flashcards in Biochemistry- Carbohydrates Deck (73)
Loading flashcards...
1
Q

What 2 monosaccharides make up lactose?

A

glucose and galactose

2
Q

What 2 monosaccharides make up sucrose?

A

glucose and fructose

3
Q

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

A

amylose

4
Q

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

A

glycogen

5
Q

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

A

Amylopectin

6
Q

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

A

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

7
Q

Which disaccharide has two glucose units?

A

Maltose

8
Q

Sailvary amylase cleaves what type of bond?

A

alpha 1,4

9
Q

maltase cleaves which linkage?

A

alpha 1,6

10
Q

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

A

brush border of mucosal cells

11
Q

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

A

fructokinase

12
Q

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

A

galactokinase

13
Q

Dextrin is only released from the hydrolysis of which polysaccharide?

A

amylopectin

14
Q

What hormone is released when glucose levels are high?

A

insulin

15
Q

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

A

the liver

16
Q

Which organ does not require insulin to take up glucose?

A

the liver

17
Q

Which hormone is released when glucose levels are down?

A

glucagon

18
Q

Which of the catecholamines stimulates gluconeogenesis?

A

epinephrine

19
Q

Glucokinase is only found in which organ?

A

the liver

20
Q

in what part of the cell does glycolysis occur?

A

cytosol

21
Q

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

A

glucokinase (hexokinase in other tissues)

22
Q

What are 3 rate limiting enzymes of glycolysis?

A

gluco/hexokinase, phosphofructokinase, pyruvate kinase,

23
Q

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

A

2

24
Q

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

A

Magnesium

25
Q

What is the net ATP gained from aerobic glycolysis?

A

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

26
Q

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

A

citrate

27
Q

What is the aerobic fate of pyruvate?

A

Acetyl-CoA

28
Q

Under anaerobic conditions pyruvate if reduced into:

A

Lactate

29
Q

What enzyme complex converts pyruvate into Acetyl-CoA?

A

Pyruvate dehydrogenase complex

30
Q

What vitamins are needed for the pyruvate dehydrogenase complex?

A

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

31
Q

What mineral is required for the pyruvate dehydrogenase complex?

A

Magnesium

32
Q

Pyruvate carboxylase converts pyruvate into what?

A

oxaloacetate

33
Q

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

A

Biotin

34
Q

Why is the production of oxaloacetate from pyruvate important?

A

starts the Krebs cycle

35
Q

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

A

The presence of pyruvate

36
Q

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

A

The presence of Acetyl-CoA

37
Q

Where does the Krebs cycle take place?

A

In the mitochondria

38
Q

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

A

Citrate

39
Q

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

A

oxaloacetate and alpha keto-glutarate

40
Q

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

A

succinyl-CoA

41
Q

Acetyl-CoA joins with what substance to form citrate?

A

oxaloacetate

42
Q

What regulates the Kreb cycle?

A

ratio of ADP to ATP

43
Q

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

A

slows it down

44
Q

What coenzymes are needed in the Krebs cycle?

A

B3- NAD
B2- FAD
B5 to make succinyl CoA

45
Q

Name 4 uses for Acetyl CoA

A

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

46
Q

Which enzyme regulates the levels of Acetyl CoA?

A

Pyruvate dehydrogenase complex

47
Q

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

A
  1. from pyruvate
  2. via beta oxidation of fatty acids
  3. alanine–>pyruvate, or from citrate
48
Q

What are the 2 reducing equivalents?

A

NAD and FAD

49
Q

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

A

Citrate

50
Q

How is oxaloacetate transported out of the mitochondrion?

A

via converstion to malate (malate shuttle)

51
Q

In what organs does the gluconeogenesis occur?

A

liver, sometime kidney

52
Q

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

A

Epinephrine

53
Q

What steroid hormone promotes the gluconeogenic pathway?

A

Cortisol

54
Q

name 3 substrates for gluconeogenesis

A
  1. alanine
  2. glycerol
  3. lactate
55
Q

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

A

inhibit it, by inhibiting fructose 1,6- diphosphotase

56
Q

What are 2 products of the hexose monophosphate shunt?

A

NADPH, Ribose

57
Q

What is the net output of the Krebs cycle?

A

3 NADH, 1 FADH, 1 GTP

58
Q

What is the key rate limiting enzyme in glycogen synthesis?

A

glycogen synthase

59
Q

What cytokine activates glycogen synthase?

A

insulin

60
Q

What hormones inhibit glycogen synthase?

A

cortisol, glucagon

61
Q

What substance in low quantities inhibits glycogen synthase?

A

cAMP

62
Q

Which tissues have high amount of glycogen?

A

liver and skeletal muscle

63
Q

Which metabolite in glycolysis is transformed into glycogen?

A

glucose-6-phosphate

64
Q

What substance carries glucose molecules to the growing glycogen chain?

A

UDP

65
Q

What is the rate-limiting enzyme in glycogenolysis?

A

phosphorylase

66
Q

How is NADPH used in the body?

A

maintains Fe in RBCs

67
Q

How many ATP molecules do you get from NADH?

A

3

68
Q

How many ATP molecules do you get from 1 FADH?

A

2

69
Q

Where does FADH enter the electron transport chain?

A

ubiquinone

70
Q

What mineral is important in the electron transport chain?

A

Fe

71
Q

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

A
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
Q

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

A

oxygen

73
Q

The process of forming ATP from electrons is called what?

A

Transduction