Carbohydrates

Question 1

Functions

Answer 1

Energy storage,
Structural
Provides O2 from oxidation of H2O and organic compounds from reduction of CO2

Question 2

What is a carbohydrate

Answer 2

A polyhydroxyaldehyde or polyhydroxyketone, or a substance that gives these compounds on hydrolysis

Question 3

Formula

Answer 3

CnH2nOn

Question 4

Monosaccharide

Oligosaccharide

Polysaccharide

Aldose

Ketose

Answer 4

A carbohydrate that cannot be hydrolysed into a simpler carbohydrate under mild conditions

Usually 2 to 10 simple sugar residues: monosaccharides linked by glycosidic bonds (Covalent bonds between the anomeric hydroxyl of a cyclic sugar and the hydroxyl of a second sugar)

Polymers of simple sugars

A monosaccharide containing an aldehyde group

A monosaccharide containing a ketone group

Question 5

Number of carbons:
3
4
5
6

Answer 5

3- Triose
4- Tetrose
5- Pentose
6- Hexose

Question 6

Optically active

Optically inactive

Dextrotatory

Levorotatory

Answer 6

the ability to rotate plane-polarised light

does not rotate plane-polarised light

rotates plane-polarised light in a clockwise direction

rotates plane-polarised light in an anticlockwise direction

Question 7

D (biological form)

L

Answer 7

hydroxyl group is on the right

hydroxyl group is on the left

Question 8

Numbering carbons

Answer 8

The numbering of the carbons

in carbohydrates proceeds from the carbonyl carbon, for aldoses, or the carbon nearest the carbonyl, for ketoses.

Question 9

𝛼

β

Answer 9

means that the -OH on the anomeric carbon is on the side of the ring opposite from the terminal -CH2OH.

means that the -OH on the anomeric carbon is on the same side of the ring as the terminal -CH2OH.

Question 10

Pyranose

Furanose

Answer 10

six-membered hemiacetal ring

five-membered hemiacetal ring

Question 11

Sugar alcohol

Deoxy sugar

Amino

Sugar Phosphates

Answer 11

CH2OH instead of CHO

1+ hydroxyl groups replaced by hydrogens: 2-Deoxy-D-ribose is a constituent of DNA

amino group at C-2

phosphate esters of glucose, fructose, and other monosaccharides are important metabolic intermediates: The ribose moiety of nucleotides such as ATP is phosphorylated at the 5’-position.

Question 12

Identifying the anomeric carbon

Answer 12

Identify anomeric carbon by looking for carbon bonded to 2 oxygens

Question 13

Bacterial cell walls

Answer 13

Composed of 1 or 2 lipid bilayers and peptidoglycan shell
Gram-positive : One lipid bilayer and thick peptidoglycan outer shell
Gram-negative: Two bilayers with thin peptidoglycan shell in between

Question 14

Glycoproteins

Answer 14

Conjugated proteins that contain one or more saccharides lacking a serial repeat unit and bound covalently to a peptide chain

Eukaryotic cells are covered with carbohydrates: diversity of glycoproteins and proteoglycans , glycocalyx

Glycosylation is the most abundant form of modification to proteins, Almost all the plasma protein of humans, except albumin are
glycoproteins

o-linked serine, threonine
n-linked asparagine

physical: Oligosaccharide structures, especially the ones with multiple outer branches, are bulky and hydrophilic