9 and 10: carbohydrates

5 functions of carbohydrates

• recognition - blood groups

• nucleic acids - ribose/deoxyribose

• fuels- glucose→atp

• structure - cellulose, chitin

• plants - photosynthesis

what is another name for carbohydrates

saccharides

carbohydrate repeating structure

(CH2O)n

• multiple hydroxyl groups

monosaccharides

• simplest carbohydrates

• have either an aldehyde or ketone

• multiple hydroxyl groups

• 3-7 carbon atoms

• names end in ose

how are monosaccharides classifies

• whether they have an aldehyde or ketone

• number of carbons

• e.g glucose is an aldosterone and has 6 carbons so is aldo hexose

glyceraldehyde

aldose - has an aldotriose group

dihydroxyacetone

a ketose - has a ketotriose grou[

optical isomerism (2 points)

• most naturally occuring monosaccharides are in D form

• molecule with n chiral carbons and no plane of symmetry have 2^n isomers

do simple ketone simple monosaccharides have isomers

• no

• arent chiral so with 3 carbons theres no isomer

rings in aldohexose

pyranose rings

rings in ketohexose

furanose rings

aldehyde + alcohol reaction

→ hemiacetal

• reversable reaction

ketone + alcohol reaction

→ hemiketal

• reversable

what are the 2 types of optical isomers for carbohydrates

L and D

when does cyclisation occur

in solution pentoses and hexoses form rings

what does cyclisation of pentose rings form

new asymmetric carbon at c1 = anomeric carbon

• alpha and beta version exist = anomers

what do the anomers do

mutarotation = folding and unfolding of the alpha and beta versions

proof of mutarotation

• beta glucapyranose rotates light 18.7 degrees

• alpha anomeric will rotate 112 degrees

• when a pure sample of an anomeric is dissolved in water the rotation will move until it settles in between

conformation of pyranose rings

chair and boat

conformation of furanose rings

envelope only

how are monosaccharides joined

• glycosidic bond between anomeric carbon and hydroxyl group

• condensation reaction

movement of saccharides when joined

one anomeric carbon locked so cant rotate but one can ( when 2 beta glucose join)

reducing sugars

the reducing end anomeric carbon is not linked so sugar can mutarotate and convert through the open chain form so is a reducing sugar

what joins sugars together

glycosyltransferases

-NH2

amino

-NHCOCH3

N-acetyl

-OPO3^2-

phosphate

-OSO3-

sulphate

-COO-

carboylate

-H

hydrogen/ dexoy

oligosaccharides

short stretches of monomer units linked together

• 1-5

polysaccharides

many monosaccharides linked together

can oh groups be replaced

yes

• amino

• acetyl

• phosphate

• sulphate

• carboxylate

• hydrogen/deoxy

glycolysis pyruvate

glucose (6c) → 2x pyruvate

where does pyruvate come from

krebs cycle in mitochondrion

how many ATP per glucose glycolysis

net 2X