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Biochem midterm exam 1 > Study guide 3 > Flashcards

Study guide 3 Flashcards

1
Q

Whats the basic formula for saccharides

A

(CH2O)n where n ≥ 3

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2
Q

starch [α

A

1→4) glucose polymer]

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3
Q

What are the functions of carbohydrates?

A
  • metabollic precursors
  • energy metabolism and storage
  • structural scaffolding for cell walls
  • molecular recognition sites
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4
Q

Cellulose [β

A

[β(1→4) glucose polymer]

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5
Q

What are some of the chemical features of carbohydrates

A

linear and ring structures
extensive h-bonding
polymeric structures via glycosidic bonds (can be branched)
one or more chiral centers

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6
Q

How many carbon atoms des monosaccharides have

A

3-7 carbons

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7
Q

How is Monosaccharides classifed

A

number of carbons, nature of carbonyl group

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8
Q

What are the 2 carbonyl group in monosaccharides

A

aldose or ketose

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9
Q

Aldoses has how many carbons

A

more than or equal to 3 Carbons

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10
Q

In glucose, out of the 6 carbons, which ones are chiral

A

4 out of 6, n-2,has 2^ n-2 possible stereoisomers

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11
Q

In fructose, out of the 6 carbons how many are chiral

A

3 of them

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12
Q

Which form of monosaccharides are predominately in nature?

A

D-form sugars are predominate in nature.

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13
Q

How are D or L- orientation decieded

A

by the configurations of -OH at the C farthest from R-CO-R

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14
Q

Why are D-from sugars predominately in nature?

A

sterospecifity of enzymes

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15
Q

What are epimers

A

a pair of stereoisomers, diastereomers

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16
Q

Whats true about epimers

A

has a different configuration at only one of several stereogenic centers.

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17
Q

Which aldose stay monomer

A

glucose

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18
Q

The cyclization of sugars happen due to the reaction between

A

reaction between C5’ alcohol and carbonyl group (most reactive)

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19
Q

What is Pyranose derived from

A

Pyran

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20
Q

What is Furanose derived from

A

furan

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21
Q

How many carbons does a Pyranose ring have

A

6-membered ring

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22
Q

How many carbons does a Furanose ring have

A

5-membered ring

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23
Q

How are α and β anomers different from each other?

A

by the -OH configuration at anomeric carbon (C1 for aldoses; C2 for ketoses

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24
Q

What is the anomeric carbon for aldoses

A

C1

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25
Q

What anomeric carbon ketoses

A

C2`

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26
Q

α: −OH and highest carbon on the

A

opposite side (below the ring)

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27
Q

β: −OH and highest carbon on the

A

same side

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28
Q

α and β interconvert spontaneously via

A

via a linear intermediate (mutarotation)

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29
Q

Sugar conformations are

A

not flat

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30
Q

Which is more stable boat or chair conformations

A

chair is slighlty more stable than boat

31
Q

What are some characteristics of sugar conformation?

A

sp3 hyb at Cs; 109.5º

32
Q

What are the two sugar conformations

A

chair and boat conformation

33
Q

Substituents can be located

A

equatorially or axially

34
Q

Bilk substituents are more stable

A

equatorially

35
Q

What is a glycosidic bond

A

a bond at the anomeric carbon

36
Q

Glycosidic bond formation reaction occurs at

A

OH and anomeric carbon

37
Q

Most polysaccharides have only how many reducing ends

A

1 reducing end

38
Q

How are disaccharides named

A

names of monosaccharides involved + linkage type

39
Q

Disaccharides are formed by

A

forming O-glycosidic bonds between monomers

40
Q

What are the structures of polysaccarades

A

linear or branched

41
Q

Which polysaccharide has a function of storage?

A

Starch and Glycogen

42
Q

Which polysaccharide has a function of structure?

A

Cellulose and chitin

43
Q

Which polysaccharide has a function of bacterial cell wall?

A

peptidoglycan

44
Q

Recognation happens at the

A

cell surface

45
Q

Why are polysaccharides needed for storage

A

keeps all monosacchrides and increases osmotic pressure

46
Q

Osmosis depends on the

A

number of solute molecules, not the kind

47
Q

Starch is the most

A

common storage polysaccharides in plants

48
Q

Starch is a mixture of

A

glucose polymers

49
Q

What is percentage of starch has α-amylose

A

20-25%

50
Q

α-amylose characterstics

A
  • left hand helix
  • linear chains of 1000s of units with α(1→4) linkage
51
Q

Amylopectin makes up, what percentage of starch

A

75-80%

52
Q

Amylopectin characterstics

A
  • liner chains with α(1→4) linkage AND branches at every 24-30 residues with α(1→6)
  • 2x10 3 - 2x10 5 glucose units (largest polymers in nature)
    α(1→4)
53
Q

What is in saliva

A

amylase

54
Q

What is the purpose of amylase in saliva

A

breaks some α(1→4) bond

55
Q

What is in the small intestines

A

pancreatic amylase

56
Q

What is in the mixture of pancreatic amylase

A

mixture of maltose and maltotriose (trisaccharides)

57
Q

α-glucosidase sequentially removes

A

1 residue at a time at α(1→4)

58
Q

β-glucosidase (debranching enzyme)

A

cuts α(1→6) linkages and α(1→4).

59
Q

Glycogen is a storage polysaccharide in

A

animals

60
Q

Where is Glycogen is prevalent where

A

in the liver (10%) and muscle (1-2%)

61
Q

which one is more branched Glycogen or amylopectin

A

glycogen every 8-12 residue have α(1→6)

62
Q

Glycogen can be

A

quickly metabolized and release glucose when blood sugar decreases

63
Q

Glycogen phosphorylase cleaves

A

α(1→4) from nonreducing end.

64
Q

Glycogen debranching

A

enzymes attack α(1→6) linkages.

65
Q

Cellulose is the most

A

abundant natural ipolymer in nature

66
Q

Cellulose role in Plant cell walls

A

rigidity and mechanical strentgh against osmotic stress

67
Q

How many types of H-bond in cellulose

A

3

68
Q

What are the 3 types of h-bonding in cellulose

A

intrastrand, interstrand, and intersheet

69
Q

Why does cellulose have 3 types of h-bonding

A

very strong, insolube, and resistant to hydrolysis

70
Q

chains in cellulose lie

A

side by side staggered to form sheets

71
Q

Long linear polymer chain in cellose can be as long

A

as 15,000 units

72
Q

Where is chitin located in

A

exoskeleton of crustaceans, insects and spider

73
Q

what are the extended liner chains of chitin made of

A

N-acetyl-glucosamine (GlcNAc)

74
Q
A

Biochem midterm exam 1 (10 decks)

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