+ BIOL1031 - structural carbohydrate

Question 1

D-glucose

Answer 1

open chain form - chiral

Question 2

enantiomers of D-glucose

Answer 2

D (made in nature)

L (made in labs)

Question 3

in cyclic

Answer 3

alpha D-glucopyranose - OH on C1 - down position

beta D-glucopyranose - OH on C1 - up position

Question 4

glycans

Answer 4

O-glycosidic linkages of monosaccharides polysaccharide - structural carbohydrate

Question 5

example of disaccharide

Answer 5

maltose - glucose + galactose

a-D-glucopyranosyl(1-4) b-D-glucopyranosyl

Question 6

cellulose

Answer 6

linear D-glucose (1-4)

from microfibrils and provide structural integrity

Question 7

hemicellulose

Answer 7

b 1-4 polymer (D-xylopyranose) + side chain - carbohydrate polymer
branched - 500-3000

Question 8

pectin

Answer 8

mixture of branched polysaccharides

a-(1-4) linked is D-galacturonic acid

Question 9

agarose

Answer 9

D-galactose linked b (1-4) + glucose = ether bridge (C3 and C6)
very complex polysaccharides - lots of substitution

Question 10

chitin

Answer 10

N-acetyl glucosamine b (1-4) linked

Question 11

chitin - found

Answer 11

exoskeleton (insect)

crabs etc

Question 12

glycosaminoglycans

Answer 12

chondroitin-4-sulphate
keratan-4-sulphate
hyaluronan

Question 13

glycosaminoglycans - contain

Answer 13

has glucuronic acid with N-acetyl galactosamine/glucosamine with 1-4 and 1-3 linkage

Question 14

proteoglycan

Answer 14

hyaluronan backbone - monomer contain keratin sulphate and chondroitin sulphate

Question 15

acetyl glucosamine

Answer 15

glucose + acetyl amino group at C2

Question 16

carbohydrate polymer

Answer 16

e.g. xylose, galactose etc

Question 17

bacteria - peptidoglycan

Answer 17

polysaccharide-peptide complex
gram +ve and gram -ve
alternate NAG and NAM linked by tetrapeptides

Question 18

gram +ve

Answer 18

stops osmotic stress

retain of dye iodine complex - trans dye

Question 19

gram -ve

Answer 19

thin, single layered between membrane

Question 20

peptidoglycan tetrapeptide

Answer 20

connected by penta-glycine inter bridge in gram +ve and -ve

Question 21

NAG

Answer 21

N-acetyl glucosamine

Question 22

NAM

Answer 22

N-acetyl muramic acid

Question 23

glycosylation

Answer 23

attachment of oligosaccharide (sugar) to proteins most pass through ER and Golgi (secretory pathway) = glycoprotein

Question 24

2 types of glycosylation

Answer 24

N-linked

O-linked

Question 25

N-linked in ER and modified in Golgi

Answer 25

by enzyme - oligosacchoryl transferase
during protein translation
attach to N-acetylglucosamine using asparagine

Question 26

dolichol

Answer 26

lipid ER membrane holding precursor oligosaccharide

Question 27

N-linked types

Answer 27

N-acetylglucosamine +NH2 of asparagine

extensively modified in Golgi = complex structure

Question 28

O-linked

Answer 28

oligosaccharide formed in Golgi

very simple structure linked to Ser, Thr of hydroxyproline

Question 29

function of glycosylation of protein

Answer 29

protein folding in ER
direct protein
protein function

Question 30

protein folding in ER

Answer 30

chaperones bond oligosaccharide of partially folded protein

Question 31

direct protein

Answer 31

lectin guide ER to Golgi and protein sorting on trans Golgi

Question 32

protein function

Answer 32

improve stability, solubility

oligosaccharide on cell surface interact with lectin - signalling

Question 33

attachment of FA and lipids example

Answer 33

GPI anchor - help binding to luminal/extracellular surface membrane

Question 34

GPI

Answer 34

glycosylphosphatidylinositol with terminal carboxyl

Question 35

lectin

Answer 35

carbohydrate protein cell-to-cell adhesion roles

Question 36

chaperone in protein folding in ER

Answer 36

calnexin and calreticulin