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Biochemistry semester 1 > Carbohydrates > Flashcards

Carbohydrates Flashcards

1
Q

carbohydrates roles

A

energy storage/ transport (metabolic energy)
cell-cell communication/ adhesion
host-pathogen/symbiont interactions
structural components
DNA/RNA components

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2
Q

carbohydrates elemental composition

A

C,H,O,S/N
2+ hydroxyl groups

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3
Q

2 simplest carbs

A

glyceraldehyde
dihydroxyacetone

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4
Q

aldose number of asymmetric carbons

A

aldoses have 1 more asymmetric carbons than ketoses

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5
Q

chiral centre

A

4 different groups
different 3D conformation

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6
Q

C1

A

aldehyde carbon

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7
Q

C2

A

carbonyl group in ketoses

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8
Q

aldehyde + alcohol

A

hemiacetal

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9
Q

pyranose

A

6C ring due to similarity to pyran

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10
Q

why do aldose sugar rings form

A

alcohol is part of same molecule as aldehyde/ ketone

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11
Q

aldose sugar rings in solution

A

dominate as more energetically favorable than open-chain form

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12
Q

ketone + alcohol

A

hemiketal

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13
Q

non-planar chair configurations

A

axial (opposite directions on adjacent carbons)
equatorial (less crowded)

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14
Q

anomers

A

sugar isomers with 2 anomeric carbons

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15
Q

additional chiral crabon for ring-formation aldoses

A

C1

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16
Q

alpha anomer

A

C1/C5 have same stereochemistry

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17
Q

beta anomer

A

C1/C5 have different stereochemistry

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18
Q

anomeric C in ketones

A

C2

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19
Q

glucose assymetric carbons and variations

A

2 stereoisomers D/lL
4 asymmetric carbons

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20
Q

what form is glucose most commonly found in?

A

D form

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21
Q

dextrorotatory

A

rotate plane of polarised light to the right

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22
Q

laevorotatory

A

rotate plane of polarised light to left

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23
Q

epimers

A

when only asymmetric C2,3 or 4 are in a different configuration to glucose

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24
Q

cylization of open-chain form of glucose

A

C5 hydroxyl group attacks oxygen atom of C1 aldehyde group to form intramolecular hemiacetal
2 anomers alpha/ beta

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25
Q

ketohexose cyclization

A

C2 keto group reacts w C6/5 hydroxyl group to form intramolecular hemiketal

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26
Q

glycosidic bond

A

bond formation between hemiacetal group of sugar and oxygen of hydroxyl group via loss of water in condensation reaction
1-4, glycosidic linkage

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27
Q

N/ S glycoside formation

A

sugars can join w other hydroxyl containing molecules (O-glycosides)/ -NHR/-SH

28
Q

Alpha glycosidic bond

A

bond on C1 opposite configuration to C5 same sugar
C1 axial in D sugar

29
Q

maltose

A

2* alpha glucopyranose
starch digestion product

30
Q

beta glycosidic bond

A

bond on C1 in same configuration to C5 of same sugar
equatorial in D sugar

31
Q

lactose

A

galactopyranosyl/ glucopyranose
milk sugar
lactase enzyme breakdown

32
Q

sucrose

A

alpha glucopyranosyl/ Beta fructofranose
transport form of carbs in plants
sucrase breakdown

33
Q

reducing end

A

terminal sugar in which C1 is unattached/ aldehyde can form

34
Q

non-reducing sugar

A

terminal sugar in which C1 is involved in glycosidic bond

35
Q

reducing sugar

A

any sugar capable of acting as reducing agent due to free eldehyde or ketone group

36
Q

alpha glucans

A

a 1,4 linkage kinked, causing polysaccharide twisting into helical structure
therefore more compact, storage molecule, degraded quickly when needed

37
Q

glycogen/ starch

A

polysaccharides of D-glucose linked by alpha 1,4- glycosidic and a 1,6 branching

38
Q

cellulose

A

beta 1,4 linked glucose planar chains cross-linked by H bonds
crystalline microfibrils

39
Q

cellulosic biofuels

A

hydrolysis of cellulose to glucose via enzymes converting glucose to ethanol in microbial fermentation

40
Q

cellulosic biofuel pros

A

no net CO2 release
use of agricultural waste
high availability

41
Q

cellulosic biofuel cons

A

recalcitrant to enzyme digestion due to structure
expensive/ inefficient

42
Q

gram neg bacteria peptidoglycan

A

1/ 2 layers
e.g. E coli

43
Q

gram pos bacteria peptidoglycan

A

40+ layers
e.g. staph. aureus

44
Q

tetrapeptide

A

4 amino acids joined by peptide bonds
cross-linked by short peptides

45
Q

membrane-associated transpeptidases

A

produce links
e.g. e.coli (direct link)
s. aureus (pentapeptide bridge) < pentaglycine bridge

46
Q

penicillin mechanism of cross-links

A

inhibtion of cross-linkage transpeptidase via substrate mimicking> slotting into transpeptidase substrate

47
Q

lysozyme mechanism

A

targets cell wall sugar backbone

48
Q

glycoconjugates

A

carbohydrates covalently linked to other molecules (e.g. proteins/lipids)

49
Q

glycoproteins

A

eukaryotic proteins with carbohydrates attached

50
Q

N-linked

A

joined to amide of asparigines (N)
usually on secreted proteins#
complex oligosaccharide structures

51
Q

N-glycosylation functions

A

protein folding
stability
cell recognition

52
Q

O-linked

A

joined to hydroxyl of serine/threonine
commonly N acetyl glucosamine
cytoplasmic
phosphorylation reciprocal

53
Q

mucins

A

O-linked glycoproteins
mucus component
cover epithelial surface for lubrication/ protection

54
Q

proteoglycans

A

proteins attached mostly by O-linkage to polysaccharides (GAGs)

55
Q

proteoglycans functions

A

joint lubricant
ECM structure
ECM adhesion mediation
bind cell proliferation factors

56
Q

GAG

A

glucosaminoglycan
disaccharide repeats of amino sugar and uronic acid sugars
sulfated
bind much water to form hydrated gel

57
Q

complex carb synthesis

A

glycosyltransferases catalyze glycosidic bond formation and trasnfer activated sugar nucleotides to molecule

58
Q

blood group A

A

produce GTA that put GalNAc on

59
Q

blood group B

A

produce GTB that put a Gal on

60
Q

blood group O

A

GT’s non-functional

61
Q

Blood group AB

A

produce both GTA/GTB

62
Q

Sars-Cov-2 viral infection

A

surface spike proteins bind to human ACE2 receptors on host cell surface
antibodies bind to spike proteins, blocking interaction between virus and ACE2
Glycans on spike limit/ reduce atibody-binding

63
Q

spike proteins

A

heavily glycosylated
involve different kinds of N-glycans
RBD’S

64
Q

RBD

A

receptor binding domains
up/ down state
needs to be up to bind to ACE2

65
Q

N-glycan types

A

high mannose
complex
hybrid
specific N-glycans stabilise RBD up state

Biochemistry semester 1 (7 decks)

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