Unit 2 - Structure Of Proteins

Question 1

What is a peptide

Answer 1

A polymer made of amino acid monomers

Question 2

Proteins consist of

Answer 2

One or more polypeptide, arranged as complex macromolecules
Hydrogen carbon oxygen nitrogen

Question 3

All amino acids have the same structure of..

Answer 3

Amine group N-H2
R group
Carboxyl group C=O-O-H

Question 4

How many EAAs are there

Answer 4

9, only obtained by what we eat

Question 5

Amino acids join when the

Answer 5

Amine and carboxyl groups react
Making a peptide bond
As the hydroxyl from carboxyl and hydrogen from amine group react in a condensation react extracting water
Makes a DIPEPTIDE

Question 6

What enzyme catalyses polypeptide (many AAs) formation

Answer 6

Peptidyl transferase
Which is present in ribosomes (site of protein synthesis)

Question 7

R group interactions form different types of

Answer 7

Bond
Which lead to the polypeptide chains of amino acids folding into complex structures (proteins)

Question 8

Primary structure

Answer 8

SEQUENCE of amino acids joining
The particular AA influence how the polypeptide chain folds into a proteins final shape, which determines function
Only bond present is peptide bonds, between the AA amine and carboxyl groups

Question 9

Secondary structure

Answer 9

Oxygen hydrogen and nitrogen of the basic AA chain interact
Hydrogen bonds may form within the AA chain pulling it into an alpha helix
If the polypeptides are parallel they can form hydrogen bonds forming sheet like structures, a beta pleated sheet

Question 10

Tertiary structure

Answer 10

Folding into final shape
The coiling (alpha helix) or folding (beta pleated sheet) brings R groups together of different amino acids,
They interact and further folding occurs

Question 11

Interactions of R groups

Answer 11

• hydrolphobic, hydrophilic interactions (weak interactions between polar and non polar)
• Hydrogen bonds (WEAKEST)
• ionic bonds between oppositely charged r groups
• disulfide bonds/bridges are COVALENT and the STRONGEST but only in R groups that have a sulfur atom

Question 12

Quaternary structure

Answer 12

Occurs from associate of two or more individual proteins, which are subunits here
Protein subunits can be identical or diff
Eg haemoglobin is 4 subunits, of 2 identical proteins

Question 13

What enzyme catalyses turning peptides back into amino acids

Answer 13

Protease