Amino Acids, protein structure, protein folding

Question 1

What happens when an amino acid is put into water?

Answer 1

it ionises
it either..
1) protonated form- protonation of the amino group and the carboxyl group

2) deprotonated form- lost a hydrogen from the amino group and the carboxyl group

Question 2

What is amino acid residue?

Answer 2

an amino acid residue is what remains of an amino acid after it has been joined by a peptide bond to form a protein

Question 3

Primary structure

Answer 3

the linear amino acid sequence

Question 4

secondary structure

Answer 4

local spatial arrangement of polypeptide backbone- the conformation ie helices

Question 5

tertiary structure

Answer 5

the overall 3d configuration

Question 6

quaternary structure

Answer 6

associatio between different polypetides to form a multi subunit protein

Question 7

What is the isoelectric point of a protein?

Answer 7

the isoelectric point pl is the pH at which there is no overall net charge

Question 8

What do polar amino acids always have?

Answer 8

sulphur as SH
oxygen
N2H

Question 9

Acidic Amino acids

Answer 9

carboxylic side chain with minus

Question 10

aliphatic

Answer 10

just carbons and hydrogens

Question 11

pKa and pH

Answer 11

lower the pKa the better the acid
PKa< pH very good acid so will get deprotonated

PKa> pH not as good more basic so protonated

Question 12

pH and isoelectric point

Answer 12

pH less than isoelctric point gets deprptonated so more negative vice versa

Question 13

What are the feature of an amino acid peptide bond?

Answer 13

Planar
Rigid
Always adopt a trans conformation
Bonds on either side are free to rotate

Question 14

What is a motif

Answer 14

Folding pattern in a globular protein with one or more element of secondary structure

Question 15

What is a domain

Answer 15

Part of a polypeptide chain in a globular protein that folds into a distinct shape and has its own role

Question 16

differences between globular and fibrous proteins

Shape
Purpose
Acid sequence
Durability 
Examples
Solubility

Answer 16

S-Shape- fibrous long and narrow, globular are spherical

P-urpose- fibrous- structural- globular- functional

Acid sequence- fibrous- repeating amino acid sequence. Globular- irregular amino acid sequence

D-urability- less sensitive to pH and temp change globular more

E-xamples- fibrous- collagen, myosin, fibrin, actin globular- enzymes, haemoglobin

S-olubility- fibrous- insolluble in water globular- soluble in water