Metabolism 1

Front 1

Describe the composition of human body

Back 1

20% protein

20% skeleton

60% water

Front 2

What is a protein?

Back 2

Essential organic compound made up of 1 or more chains of amino acids

Front 3

What is the simplest amino acid?

Back 3

glycine

Front 4

Which amino acids have hydroxyl groups and can be phosphorylated?

Back 4

Serine, threonine, tyrosine

Front 5

Which amino acid has a sulfur group in side chain?

Back 5

cysteine

Front 6

Which amino acids are basic?

Back 6

lysine and arginine (always protonated)

histidine protonated below pH 6

Front 7

Which amino acids are negatively charged?

Back 7

Glutamic and Aspartic acid

Front 8

What form are amino acids found in?

Back 8

L-form (all chiral)

Front 9

How strong is a peptide bond?

Back 9

Kinetically stable - lifetime in aq is 1000 years

Front 10

What is stearic hindrance?

Back 10

Only conformations in which side chains don't clash with main chain are allowed

This is because no rotation about peptide bond but other bonds can rotate

C=O and NH in same plane of molecule

Front 11

How do disulphide bridges form?

Back 11

Cysteine in side chains are oxidised

Front 12

What bonds hold proteins together?

Back 12

Disulfide, cysteine in side chains oxidised to form a covalent bond;

hydrogen, 2 atoms with partial negative share hydrogen with partial positive;

ionic, electrostatic attraction between charged side chains;

peptide;

vdW;

hydrophobic interactions, hydrophobic side chains within interior of protein

Front 13

Under what circumstances are ionic bonds in proteins strongest, and where are ionic bonds generally found?

Back 13

IN interior of protein with no water

generally found on surface of protein so can be neutralised by counterion

Front 14

What are hydrophobic interactions?

Back 14

Hydrophobic side chains contained within interior of molecule

Front 15

What orientation are alpha helices?

Back 15

right handed due to L-amino acids

Front 16

Describe structure of alpha helix?

Back 16

H-bonds

between nH group and C=O group

4 amino acids along the chain

3.6 residues per helix turn

Right handed helix

Front 17

Describe the structure of beta pleated sheet

Back 17

Hydrogen bonds between 2 or more strands

can be parallel or ant parallel

Front 18

What do chaperones do?

Back 18

Ensure folding continues along most favourable pathway

Front 19

What are common denaturants?

Back 19

Urea - breaks H-bonds

2-mercaptoethanol breaks disulfide

Front 20

What is the tertiary structure of proteins?

Back 20

Arrangement of secondary structures into globular structures (domains)