carbohydrates

Question 1

what makes sucrose

Answer 1

glucose and fructure

Question 2

what makes lactose

Answer 2

galactose and glucose

Question 3

what determines whether a monosacc is an aldose or ketose

Answer 3

the carbonyl carbon.

Question 4

what is an enantiomer

Answer 4

both molecules are mirror images of each other depending on where the OH group is. if it is on the left = L config
it is on right = D config

Question 5

what is a diasteromers

Answer 5

when two sugars have identical molecular formula, a diff arrangement of atoms and are not enantimers

Question 6

what governs whether an amino acid is L or D config

Answer 6

the NH3 group

Question 7

what is an epimer

Answer 7

a subgroup of diastereoisomers where there is only one difference at one chiral centre- are NOT mirror images so they are not enantiomers.

Question 8

are ring or linear structures more stable

Answer 8

ring- they typically predominate since they are lower in energy

Question 9

what happens to the carbonyl carbon after completion of cyclic structure

Answer 9

reduced to an alcohol

Question 10

which sugars typically undergo intramolecular cyclization

Answer 10

pentoses and hexoses

Question 11

what happens to the carbonyl carbon after cyclization

Answer 11

it becomes a new chiral centre called the anomeric carbon- at C1 of aldoses and C2 of ketose

Question 12

what is a pyranose

Answer 12

six membered oxygenated ring with a pyran structure

Question 13

what is a furanose

Answer 13

five membered oxygenated ring with the furan structure

Question 14

can glucose adopt a furanose strucrure

Answer 14

yes as well as its pyranose form

Question 15

does pyranose or furanose forms dominate glucose at equilibrium

Answer 15

pyranose

Question 16

how do disaccharides form ? (maltose)

Answer 16

where an OH of one glucose condenses with the intramolecular hemiacetal of the other glucose , where H2O is eliminated and a glycosidic bond is formed

Question 17

what is an O-glycosidic bond (reducing)

Answer 17

where a disaccharide is formed by linkage between two anomeric carbons. the product of this linkage is one acetal group and one hemiacetal.

there is a reducing end

Question 18

what is an O glycosidic bond (non reducing)

Answer 18

where linkage occurs between two anomeric carbons. the end product has two acetal groups and no hemiacetals. there are no reducing ends

Question 19

how can you tell if a sugar is a reducing sugar

Answer 19

if the O2 on the anomeric carbon is not attached to any other structure, it is a reducing sugar.

Question 20

what are the two types of polysaccharides

Answer 20

homo-poly saccharides = one monomer unit
hetero-polysaccharides = multiple monomer units
linear= one type of glycosidic bond
branched= multiple types of glycosidic bonds

Question 21

what types of bonding does cellulose have

Answer 21

B glucose 1-4

Question 22

what type of bonding does amylose and amylopectin have

Answer 22

amylose = a 1-4
amylopectin = a 1-4 or 1-6

Question 23

what type of bonding does glycogen have

Answer 23

a 1-4 and a 1-6

Question 24

what type of polysaccharide is glycogen

Answer 24

branched homopolysaccharide

Question 25

what comprises starch

Answer 25

amylose and amylopectin

Question 26

describe the metabolism of glycogen and starch

Answer 26

• insoluble due to molecular weights
• tend to form granules in cells which often contain enzymes which synthesize + degrade the polymers

Question 27

describe the reducing and non reducing ends of amylopectin and glycogen

Answer 27

these have one reducing end and many non-reducing ends. enzymatic processing takes place in many non-reducing ends

Question 28

is cellulose linear or branched

Answer 28

linerar

Question 29

what is chitin

Answer 29

linear homopolysaccharide of N-acetylglucosamine (B 1-4)

Question 30

what are glycosaminoglycans

Answer 30

modified polysacc to have an amino group + some negatively charged groups
made of repeating disacc units where:
one monomer = N-acetyl-glucosamine or N-acetyl-galactosamine
second monomer = neg charged uronic acid/galactose/sulfate esters

Question 31

where are glycosaminoglycans found

Answer 31

-as hyaluronate in connective and epi tissues
-chondroitin sulfate in cartilage ECM (shock absorber)
-keratan sulfate in bone and cartilage (shock absorb)
-heparin anticoag

Question 32

write about heparin and heparan sulfate

Answer 32

heparin = linear polymer. heparan sulfate = heparin-like polysaccharide but is attached to proteins
prevents blood clotting by activating thrombin (protease inhibitor)
regulates development and formation of blood vessels.
can bind to viruses and bacteria to decrease their virulence

Question 33

what is a proteoglycan

Answer 33

proteins that are attached to glycosaminoglycans.
syndecans: protein as a single transmembrane domain
glypicans: protein is anchored to a lipid membrane

Question 34

what are the functions of proteoglycans

Answer 34

lubricate joins
structural component of connective tissue
binding of cells to ECM
regulation of movement of molecules through the matrix

Question 35

how can you tell an o-linked glycoprotein from an n linked

Answer 35

N linked has an NH2 group at the anomeric carbon to amino acid bond

Question 36

what is a glycolipid

Answer 36

lipids with covalently bound olgiosaccharide
- part of cell membranes
- lipopolysaccharide covering in peptidoglycan layer in G-neg bacteria