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CARBOHYDRATES (CHEM LEC) > GLYCOSIDIC LINKAGE > Flashcards

GLYCOSIDIC LINKAGE Flashcards

1
Q

Disaccharides (C12H22O11)

A

•maltose
•sucrose
•cellobiose

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2
Q

C12H22O11 + H2O ➡️ C6H12O6

A

✅ white, crystalline, sweet solids

➡️ sucrose- very soluble in water
➡️ maltose- fairly soluble
➡️ lactose- slightly soluble
➡️ optically active
➡️ too largely to pass the cell membrane

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3
Q

DISACCHARIDES:
• maltose

A

➡️ a cleavage product of starch (e.g., amylose), is a disaccharide with an a(1-4) glycosidic link between C1-C4 OH of 2 glucose. It is the a anomer (C1 0 points down)

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4
Q

Celloboise

A

➡️ a product of cellulose breakdown, is the other wise equivalent B anomer (O on C1 points up). The B(1-4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other.

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5
Q

Maltase

A

➡️ hydrolyzes alpha glycosidic linkage

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6
Q

disaccharides: sucrose and lactose

➡️sucrose (table sugar) has a _______ bond
➡️lactose (milk sugar) is composed of _____ & _____

A

➡️sucrose (table sugar) has a glycosidic bond linking the anomeric hydroxyls of glucose & fructose.

➡️lactose (milk sugar) is composed of galactose & glucose.

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7
Q

The configuration at the anomeric C of glucose is a (O points down from ring), the linkage is a(1-2)

The full name of sucrose is _______________

A

a-D-glucopyranosyl1-(1-2)-B-D-fructopyranose.

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8
Q

Lactose is with B(1-4) linkage from the anomeric OH of galactose. It’s full name is ________________

A

B-D-galactopyranosyl1-(1-4)-a-D-glycopyranose

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9
Q

Polysaccharides:

A

•plants store glucose as amylose or amylopectin, glucose polymers collectively called starch

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10
Q

Glucose storage in ________ form minimizes osmotic effects.

A

polymeric

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11
Q

________ is a glucose polymer with a(1-4) linkages.

A

Amylose

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12
Q

The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the________ ___.

A

reducing end

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13
Q

Amylopectin

A

•is a glucose polymer with mainly a(1-4) linkages, but it also has branched formed by a (1-6) linkages.

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14
Q

The branched produce a compact structure & provide multiple chain ends at which ______ ______ can occur.

A

enzymatic cleavage

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15
Q

Glycogen

A

•the glucose storage polymer in animals, is similar in structure to amylopectin.

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16
Q

glycogen has more a(1-6) ________

A

branches

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17
Q

The highly branched structure permits ______ ______ release from glycogen stores, e.g., in muscle during exercise.

A

rapid glucose

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18
Q

The ability to rapidly mobilize glucose is more essential to _______ than to plants.

A

animals

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19
Q

Cellulose

A

•a major constituents of plant cell walls, consists of long linear chains of glucose with B(1-4) linkages.

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20
Q

Every other glucose is flipped over, due to ______________

A

due to B linkages.

this promotes intro-chain and inter-chain H-bonds and can der Waals interactions, that cause cellulose chains to be straight & rigid, and pack with a crystalline arrangement in thigh bundles- microfibrils

see: botany online website; website at Georgia tech

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21
Q

Multi subunit Cellulose Synthase___________

A

complexes in the plasma membrane spin out from the cell surface microfibrils consisting of 36 parallel, interacting cellulose chains.

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22
Q

These microfibrils are ____ ______.

A

very strong

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23
Q

The role of cellulose is to ____________

A

impart strength and rigidity to plant cell walls, which can withstand high hydrostatic pressure gradients.

Osmotic swelling is prevented.

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24
Q

Glycosaminoglycans (mucopolysaccharodes)

A

are linear polymers of repeating disaccharides.

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25
Q

The constituent monosaccharides tench yo be modified, with _____ groups, _____ groups, ______ _____ ad _____ groups etc.

A

with acidic group, amino groups, sulfate hydroxyl and amino groups etc.

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26
Q

Glycosaminoglycans tend to be _______ charged, because of the prevalence of acidic groups.

A

Negatively charged

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27
Q

HTA Lito ate (hyalouronan) is a _________ with a repeating disaccharide consisting of 2 glucose derivatives, glucuronate (glucuronic acid) & N-acetyl-glucosamine.

A

Glycosaminoglycan

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28
Q

The glycosidic linkage are ______ & _____

A

B(1-3) & B(1-4)

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29
Q

Proteoglycans are _______ that are covalently linked to sirens residues of specific ______ ______.

A

glycosaminoglycans ; core proteins.

30
Q

The glycosaminoglycan chain is synthesized by _____ addition of sugar residues due to the core protein.

A

sequential

31
Q

Some proteoglycans of the extracellular matrix ____ non-covalently to ______ via protein domains called _____ ____

A

bind; hyaluronate; link molecules.

32
Q

Multiple copies of _____ proteoglycan associate with hyaluronate in cartilage to form large complexes .

A

aggrecan

33
Q

Versican

A

another proteoglycan, binds hyaluronate in the extrallular matrix of loose connective tissues.

34
Q

Heparan sulfate

A

•is initially synthesized on a membrane-embedded core protein as a polymer of altering N-acetylglucosamine and glucuronate residues.

35
Q

In segments of the polymer,

glucuronate residues may be converted to the sulfates sugar _____ acid

A

iduronic acid

36
Q

N-acetylglucossmine residues may be ______ And/or _____.

A

deacetylated and/or sulfated.

37
Q

Heparin

A

•a soluble glycosaminoglycan found in granules of mast cells, has a structure similar to that of heparan sulfates, but is more highly sulfated

38
Q

Heparin inhibits clot formation when released into the blood, by interacting with the _______ _______.

A

Protein antithrombin

39
Q

Heparin has an ______ ______ ______.

A

extended helical conformation.

40
Q

Charge repulsion

A

by the many negatively charged groups may contribute to this confirmations

41
Q

Some cell surfaces hepari sulfate

A

glycosaminoglycans remain covalently linked to core proteins embedded in the plasma membrane.

42
Q

The core protein of a _______ heparan sulfate proteoglycan as a a single ______________, as in simplified diagram

A

syndecan; transmembrane a-helix

43
Q

The core protein of _____ heparan sulfate proteoglycan is attached to the outer surface of the plasma membrane via covalent _______ modified phosphatidylinositol _____

A

glypican; linkage to: lipid

44
Q

Proteins involved in ____ & ____ at the cell surface recognize & bend heparan sulfate chains.

A

Signaling & adhesion

45
Q

Binding of some _____ factors (small proteins) to cell surface receptors is enhanced by their binding alto to heparan sulfates.

A

growth

46
Q

Regulated cell surface ____ enzymes may remove _____ groups at particular locations on heparan sulfate chains to ____ affinity for signal proteins, e.g., growth factors

A

Sulf; sulfate; alter

47
Q

Oligosaccharides

A

are covalently attached to proteins or to membrane lipids may be linear or branched chains.

48
Q

O-linked Oligosaccharide

A

chains of glycoproteins vary in complexity. They link to a protein via a glycosidic bond between a sugar residue & a serine or threonine OH

49
Q

O-linked oligosaccharides have roles in _______, _______, and _______ ________.

A

recognition, interaction, and enzyme regulation.

50
Q

N-acetylglucosamine (GlcNAc)

A

•a common O-linked glycosylation of protein serine or threonine residues.
•many cellular proteins, including enzymes & transcription factors are regulated by reversible GlcNAc attachment.
•often attachment of GlcNAc to a protein OH alternates with phosphorylation, with these 2 modifications having opposite regulatory effects (stimulation or inhibition)

51
Q

N-linked oligosaccharides of glycoproteins tend to be ______ and _____

A

complex and branched.

52
Q

First N-acetylglucosamine is linked to a protein via the __________ of an asparagine residue in a particular 3-amino acid sequence

A

side-chain N

53
Q

N-linked oligosaccharides
key:

NAN =
Gal=
NAG=
Man=
Fuc=

A

NAN= N-acetylneuraminate
Gal= galactose
NAG= N-acetylglucosamine
Man= mannose
Fuc= fucose

53
Q

N-linked oligosaccharides
key:

NAN =
Gal=
NAG=
Man=
Fuc=

A

NAN= N-acetylneuraminate
Gal= galactose
NAG= N-acetylglucosamine
Man= mannose
Fuc= fucose

53
Q

N-linked oligosaccharides
key:

NAN =
Gal=
NAG=
Man=
Fuc=

A

NAN= N-acetylneuraminate
Gal= galactose
NAG= N-acetylglucosamine
Man= mannose
Fuc= fucose

53
Q

N-linked oligosaccharides
key:

NAN =
Gal=
NAG=
Man=
Fuc=

A

NAN= N-acetylneuraminate
Gal= galactose
NAG= N-acetylglucosamine
Man= mannose
Fuc= fucose

54
Q

the N-linked oligosaccharides chain is modified by ______ and _____ of residues, to yield a characteristic branched structure.

A

removal and addition

55
Q

many proteins _______ by cells have attached N-linked oligosaccharide chain

A

secreted

56
Q

________ disease have been attributed to deficiency of particular enzymes involved in synthesizing or modifying oligosaccharide chain of these glycoproteins.

A

Genetic disease

57
Q

such disease, and ____ _____ studies in mice, have been used to define pathways of modification of oligosaccharide chains of glycoproteins and glycolipids.

A

gene knockout

58
Q

_______ chains of plasma membrane glycoproteins and glycolipids usually face the ______ of the cell.

A

Carbohydrate chain ; outside of the cell

59
Q

_______ chains of plasma membrane glycoproteins and glycolipids usually face the ______ of the cell.

A

Carbohydrate chain ; outside of the cell

60
Q

they have roles in cell-cell _______ and _____, and in forming a protective layer on the surface of some cell.

A

interaction and signaling

61
Q

Lectins

A

•are glycoproteins that recognizes and bind to specific oligosaccharides

62
Q

Concanavalin A & wheat germ agglutinin

A

•are plant lectins that have been useful research tools.

63
Q

the C-type lectin-like domains is a ________ binding carbohydrate recognition domain in many animal lectins.

A

Ca++

64
Q

Recognition /binding of CHO

A

•moieties of glycoproteins, glycolipids & proteoglycans by animal lectins is a
factor in:
• cell-cell recognition
•adhesion of cells to have the extracellular matrix
• interaction of cells with chemo lines and growth factors.
• recognition of disease-causing microorganisms
• initiation and control of inflammation

65
Q

Examples of animal lectins:

A

•Mannan-binding lectin (MBL)
➡️a glycoprotein found in blood plasma.

It binds cell surface carbohydrates of disease-causing microorganisms & promotes phagocytosis of these organisms as part of the immune response.

66
Q

Selectins

A

are integral proteins of mammalian cell plasma membranes with roles in cell-cell recognition & binding

67
Q

the C-type lectin-like domain

A

is at the end of multi-domain extracellular segment extending out from the cell surface

68
Q

cleavage site

A

just outside the transmembrane a-helix provides a mechanism for regulated release of some lectins from the cell surface

69
Q

cytosolic domain

A

participates in regulated interaction with the actin cytoskeleton.

CARBOHYDRATES (CHEM LEC) (2 decks)

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