Topic 2: Protein Structure

Question 1

The general structure of an amino acid

Answer 1

Amino group (NH3+), alpha carbon, carboxyl group (COO-), R group (non-polar, polar uncharged, acidic(negatively charged), basic (positively charged))

Question 2

How to form dipeptide

Answer 2

Remove H from NH2 and OH from carboxyl (dehydration by removing water). 2 amino acids + 1 peptide bond= dipeptide

Question 3

What is the head and what is the tail of an amino acid

Answer 3

N-terminus head where NH3+ is, and C- terminus tail where carboxyl is

Question 4

Describe the 4 protein structure levels and the bonds needed in each structure

Answer 4

Primary: polypeptide chain (peptide bonds)
Secondary: alpha helix, beta pleated sheets (hydrogen bonds between NH3+ and carboxyl), localized folding (NH3+ and carboxyl are close together)
Tertiary: Protein starts folding globally (sides chains are far but still connect) by hydrogen bonds, ionic bonds, van Der Waals, or disufide bridges (strongest)

Quaternary: more than 1 polypeptide
Polypeptide(amino acid string) =subunit
monomer: 1 subunit
dimer: 2 subunits (heterodimer(2 different polypeptides) or homodimer(2 same polypeptides))
trimer: 3 subunits
tetramer: 4 subunits (heterotetramer or homotetramer)

Question 5

Protein Structure: Globular or Fibrous meaning

Answer 5

Globular(tetramer): like a blob
Fibrous (trimer):fibres that looks like a braid

Question 6

Domain vs subunit meaning

Answer 6

Areas that make up a protein and have their own individual duties that make the protein function (part of a polypeptide)

Subunit: a whole polypeptide

Question 7

What are chaperones

Answer 7

Help a protein fold

Question 8

What is denaturation

Answer 8

When bonds forming the protein break causing the protein to break down into primary structure again