Lecture 10 - Carbohydrates

Question 1

Carbohydrate Structure

Answer 1

Can be linked together in more way than proteins or nucleic acids
Have direction - non-reducing end or reducing end depending on presence of hydroxyl group at anomeric C

Question 2

Carbohydrate Terms

Answer 2

Glycan - indicates a monosaccharide, oligosaccharide or polysaccharide
Complex Carbs - polysaccharides containing one or more types of monosaccharides, glycoconjugates
Sugar derivatives - phosphorylated sugars, amino sugars and nucleotides

Question 3

Glycomics

Answer 3

Glycan structures not coded by genome
However, enzymes for glycan synthesis and degradation encoded by genome
Glycome - study of carbs in a cell
Glycomics - study of all glycomes

Question 4

Roles of Carbs

Answer 4

Energy source
Cell recognition
Cell to cell communication 
Signal transduction
Inflammation
Fertility

Question 5

Energy and Info molecules

Answer 5

Hexoses
- Fuel/energy
Pentoses
- Info molecules (DNA, RNA)
- Energy molecules (ATP)
- Coenzymes (NADH)

Question 6

Whats the difference between an Enantiomer and Diasteromer

Answer 6

Enantiomer - when there are different configurations of H and OH at all four stereocentres in hexose
Diasteromer - when there are different configurations of H and OH at one or more but not all stereocentres in the hexose

Question 7

Glycosidic Bonds

Answer 7

Covalent bond formed by condensation of two monosaccharides with elimination of water
Can be alpha or beta depending on configuration of anomeric carbon
Type of bond determines structural and functional properties of carbohydrate

Question 8

Examples of Heteropolysaccharides

Answer 8

Hyaluronic Acid - polymer of alternating monomers of D-glucuronic acid and N-acetyl-D-glucosomine
Keratin Sulphate - alternating galactose and N-acetylglucosamine-6-sulfate
Heparin - alternating ioduronic acid and glucosamine sulphate

Question 9

Glycoconjugates

Answer 9

Glycoproteins
- Protein with glycans attached
- attached through covalent bond with N atoms odf asparagine or O atoms of serine, threonine
Proteoglycans - glycosaminoglycans attached to core protein
- bottle brush strcuture
- extracellular matrix
Glycolipids 
- glycans attached to sphingolipids

Question 10

Functions of Glycoproteins

Answer 10

Cell to cell interactions  (adhesion)
Hormones
Enzymes
Blood clotting
Immune recognition