Proteins: Structure and Function Flashcards Preview

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Flashcards in Proteins: Structure and Function Deck (17)
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1
Q

Draw an Amino Acid (3)

A

Allocate:

  1. Amino Group
  2. Carboxyl Group
  3. R Group
2
Q

What type of bonds exist between amino acids? What reaction makes bond? (2)

A
  1. Peptide Bond

2. Condensation Reaction

3
Q

How is folding determined in primary structure of a protein? (3)

A
  1. By the distribution of the hydrophobic and hydrophillic side chains.
  2. Hydrophillic (polar) side chains form hydrogen bonds with water on outside
  3. Hydrophobic (non-polar) side chains are packed into core.
4
Q

What are the most stable Secondary protein structures? How does their shape form?

A
  1. Alpha - helice and Beta Pleated sheet

2. Shape forms due to hydrogen bonds between carbonyl groups and amino groups along the chain.

5
Q

What are the arrangements of Alpha Helix and Beta Pleated sheet (Shape, AA length, Side chains, normal environment) (4)

A

Alpha Helix - Spiral, 5-20aa, Sidechains face outwards, - Abundant in the phospholipid bilayer. Hydrophobic side chains interact with hydrocarbon tails of the phospholids.

Beta Pleated sheet - Flat and arranged laterally, Sidechains extend above and below Beta Sheet

6
Q

What are other secondary structures of proteins? (2)

A
  1. Loops and Turns (3-5 aa, have hydrophilic residues and found on the surface of proteins)
  2. Random Coils - Chains with random configuration
7
Q

What are the weak side-chain interactions in proteins? (3)

A
  1. Hydrogen Bonds
  2. Van Der Waals
  3. Electrostatic Attractions.
8
Q

What type of structure are Keratin and Collagen, what is the arrangement? (3)

A

Tetiary Structure (Coiled Coils)

These are formed from 2/3 Alpha helices wound around each other with hydrophobic core.

9
Q

What are Quaternary Structures. Give an example? (2)

A
  1. When proteins associate with each other to generate high order structures.
    Example: Haemoglobin is formed of 2 alpha subunits and 2 beta subunits
10
Q

What is post-translational modification? (2)

A
  1. Proteolytic cleavage or adding a modifying group to a protein
  2. It modulates function of eukaryotic proteins altering activity, turnover, and interaction.
11
Q

What are the types of post-translational modification? (2)

A
  1. Phosphorylation: Addition of phosphate to amino acid.

2. Glycosylation: Addition of Carbohydrates to specific site of protein.

12
Q

What type of bond do excreted tertiary structure proteins typically have? What role does it play? (3)

A
  1. Disulfide bond.
  2. Commonly between Cysteines between each other in folded structure.
  3. Gives Strength but does not alter shape.
13
Q

What is ‘Folding Funnel’ in Protein formation? Why is it important (2)

A
  1. Proteins spontaneously fold into 3-D conformation of the lowest free energy.
  2. This folding process is energetically favourable as releases heat and increases disorder in the universe.
14
Q

For proteins that do not fold spontaneously, what molecules can help? (2)

A

Molecular Chaperones (Heat shock Proteins and Chaperonins).

They do not change 3D structure, speed up folding, prevent protein aggregation and prevent unproductive intermediates.

15
Q

What is the charge of these amino acid side chains? (2)

Glutamic acid
Aspartic acid
Lysine
Arginine 
histidine
A

-ve charge (carboxylic group):
Glutamic acid
Aspartic acid

+ve charge (N group)
Lysine
Arginine
histidine

16
Q

What role does mutated CFTR play in Cystic Fibrosis?

A

Mutation occurs due to deletion of amino acid Phenylalanine at 508.

Mutant CTFR protein becomes stuck in the endoplasmic reticulum leading to abnormal chloride conductance out of the cells

17
Q

What is Creutzfeldt–Jakob disease (CJD ) and how does it develop? (4)

A

It is a variant of Mad Cow Disease.
Transmitted by misfolded prions. They promote refolding of other prions into a disease conformation upon contact.

They are shaped as Beta-sheets (amyloid fibril) so are very stable, causing slow death of nerves in brain.