Amino acids and proteins

Question 1

what are some functions of proteins?

Answer 1

catalysts - enzymes

transporters

structural support (collagens/bone)

immune protection

receptors

signalling

Question 2

key features of proteins

Answer 2

polypeptides

amino acids sequences encoded by genes

folds into complex 3D structure

folding depends on chemical and physical properties

Question 3

when are AAs pronated/depronated?

Answer 3

pronated when pH solution < pK value

depronated when ph solution > pK value

Question 4

what is the isoelectric point of proteins?

Answer 4

pI is pH where proteins has no overall net charge

Question 5

how is a peptide bond formed?

Answer 5

link of 2 AAs w/ removal of water molecule

covalently bonded via peptide bond which forms b/w carboxyl group of one AA and amine group of second

Question 6

key features of peptide bond

Answer 6

all atoms bonded in same plane

no rotation around peptide bond due to double bond

carbonyl O2 and amide H in trans orientation

Question 7

features of collagen

Answer 7

triple helical arrangement

contains Gly repeating sequence

hydrogen bonds stabilise interactions

fibrils form from covalently cross-linked collagen molecules

Question 8

what are motifs?

Answer 8

folding patterns containing 1 or more elements of secondary structure

Question 9

what are domains?

Answer 9

part of polypeptide chains that fold into a distinct shape

Question 10

four levels of protein structures

Answer 10

primary - linear sequence, covalent bonds, insulin

secondary - spatial arrangement of backbone, hydrogen bonds, alpha/beta sheets

tertiary - 3D arrangements, van der wals, H and covalent, myogloblin

quartenary - 3D structure of all protein structures, all above bonds, haemoglobin

Question 11

example of misfolding protein

Answer 11

amyloid fibres

beta backbone forms first

insoluble form of protein

cause of alzheimers