Protein Structure and Function Flashcards
What is a protein?
Polymer of Amino Acids linked via Peptide bonds.
What is a peptide bond?
Dehydration reaction between Amino (Basic) group of one amino acid and the Carboxylic (Acidic) group of another amino acid.
Are peptide bonds able to rotate? if not where can rotation occur?
No, rotation can occur at the single bonds between the C-R atom and it’s neighbours.
Are the ‘R’ groups of amino acids more likely to be cis or trans? and why?
Trans, there is repulsion between cis side chains meaning cis is less stable.
What marks the start of a polypeptide?
N-terminus
What does N-terminus stand for?
N indicates the Amino group which contains Nitrogen.
What marks the start of a polypeptide?
C-Terminus
What does C-terminus stand for?
C Indicates Carboxylic group which contains Carbon
What defines the shape that a polypeptide will have?
The chemical properties of the amino acids and their sequence.
Name the 2 types of secondary structures?
Beta sheets and Alpha Helices
What is the formation of secondary structures driven by?
Hydrogen bonds forming between the polypeptide backbone.
Which 2 types of ‘R’ groups have more affinity for beta sheet structures?
large aromatic rings and beta-branched ‘R’ groups.
What are the 3 bonds/interactions involved in the forming of a quaternary structure?
- Ionic interactions
- hydrogen bonding
- hydrophobic interactions
Can quaternary structures be dynamic?
yes
What are the 3 protein structural categories mentioned in the lecture?
- Globular
- Fibrous
- Membrane Proteins
Are globular proteins soluble?
yes
Are fibrous proteins soluble?
no
How would you differentiate the primary and secondary structure of globular vs. fibrous proteins?
Globular have irregular seq. and structure
Fibrous is often repetitive at the primary and secondary level
Are globular proteins stable??
they have a lower stability
Are fibrous proteins stable??
yes, highly.
Give 3 examples of globular proteins
- enzymes
- hemoglobin
- antibodies
Give 3 examples of fibrous proteins
- Keratin
- Actin
- Collagen
Contrast Globular and fibrous proteins in terms of quaternary structure
Globular proteins of have little to no structure on the quaternary level.
Fibrous proteins have a high level of quaternary structure
List 4 functions of (trans) Membrane Proteins
- Transport
- signalling
- adhesion
- Reception
What (secondary) structure do the TM section of Membrane Proteins often have?
Alpha Helix (single or bundle)
Whats another organelle specific (secondary) structure that the TM section of Membrane Proteins can have? (name the organelle also)
Beta-barrel, found in the mitochondria
