Protein Structure

Question 1

What are disulfide bridges?

Answer 1

Form between the sulfur atoms of sulfhydryl (-SH) groups on two amino acids that may reside on one polypeptide chain or two separate chains

Question 1

Which residue is normally responsible for disulfide bridges?

Answer 1

Cysteine

Question 2

What are the functions of protein?

Answer 2

Receptors, hormones, enzymes, antibodies, blood, bone, collagen, nails

Question 3

What are the properties of amino acids?

Answer 3

Polar, hydrophobic, acidic, aromatic ring, pH, hydrophobic, hydrophilic

Question 4

What is PKU?

Answer 4

Inability to break down phenylanine

Question 5

What are they symptoms of PKU?

Answer 5

Eczema, tremors, epilepsy, self-harm, behavioural difficulties

Question 6

How many does if affect

Answer 6

1 in 10000

Question 7

How do they test and treat PKU?

Answer 7

Heel prick, low protein diet plus amino acid supplements

Question 8

How is PKU transferred?

Answer 8

Autosomal recessive condition

Question 9

What is the structure of an amino acid?

Answer 9

Amine group, side chain, carboxyl group

Question 10

Which stereoisomer are amino acids?

Answer 10

L-form

Question 11

How are amino acids joined?

Answer 11

Peptide bond-codensation reaction

Question 12

What is the primary structure?

Answer 12

Sequence of amino acids, nothing about 3D structure

Question 13

What is PAGE?

Answer 13

Polyacyramid gel electrophoresis- separates proteins based on molecular weight

Question 14

How do you visualize protein?

Answer 14

Stain with coomassie blue, use size markers

Question 15

What is secondary structure?

Answer 15

Local spatial arrangements of AA in a selected segment or polypeptide
A-helix or b-sheets

Question 16

What is an a-helix?

Answer 16

Hydrogen bonds between amino acids of the same polypeptide
Cylinder

Question 17

What sort of proteins are a-helix found in?

Answer 17

Key cellular functions- such as transcription factors

Question 18

What are B-sheets?

Answer 18

Zig zag shapes
Hydrogen bonding occurs between neighbouring chains
Antiparallel, parallel

Question 19

What is tertiary structure?

Answer 19

3D folding of a peptide
Seen by x-ray crystallography

Question 20

What is quaternary structure?

Answer 20

Two or more polypeptide chains- this arrangment

Question 21

What is a fibrous protein?

Answer 21

Long strands or sheets
Support, shape and external protection

Question 22

Name a fibrous protein

Answer 22

A-keratin, collagen, silk fibroin

Question 23

Name a globular protein

Answer 23

enzymes, regulatory proteins, myoglobin

Question 24

What is a globular protein?

Answer 24

Polypeptide chains folded into spherical or globular shape

Question 25

What is myoglobin?

Answer 25

Oxygen binding portion of muscles cells, single polypeptide, single heme group, small

Question 26

What is haemoglobin?

Answer 26

Four polypeptide chains (tetramer), four heme groups, globin (two a-chains two b-chains)
2 subunits

Question 27

What is sickle cell anaemia?

Answer 27

Inherited red blood cell disorder
Not enough healthy RBCs to carry oxygen
Crescent moons

Question 28

Who is sickle cell anaemia common in?

Answer 28

African or Caribbean people

Question 29

What mutation causes sickle cell?

Answer 29

Missense mutation, val instead of glu

Question 30

What does deletion at d508 cause

Answer 30

Cystic fibrosis, phenylaline missing, accounts for 70% of patients

Question 31

What genetic effect causes huntingdons?

Answer 31

More CAG repeats than normal (36 repeats) on chromosome 4, more glutamine, protein no longer folds right so causes neuronal damage

Question 32

What protein misfold causes parkinsons?

Answer 32

Alpha- synuclein, clump together, dopamine decreases