Proteins (J)

Question 0

List the 5 elements that make up amino acids

Answer 0

Carbon
Hydrogen
Oxygen
Nitrogen
Sulphur

Question 1

What are proteins made up of

Answer 1

Amino acids

Question 2

Central carbon atom has 4 different chemical groups attached to it what are they?

Answer 2

A hydrogen atom
A basic amino group
An acidic carboxyl group
A variable “R” group ( or side chain)

Question 3

How many different amino acids are there?

Answer 3

20 all have similar chemical structures but behave very differently because they have different side groups

Question 4

Amino acids supplied through are diet are known as

Answer 4

Essential amino acids

ie leucine, lysine, valine, methionine

Question 5

Amino acids made by the body are known as a process known as

Answer 5

Transamination which occurs in the liver

Question 6

Proteins form which reaction

Answer 6

Condensation reaction which links amino acids together

Question 7

What happens in the condensation reaction

Answer 7

A molecule of water is produced from a linkage between the -COOH of one amino acid and the NH2 of the next this is known as a Peptide Bond

Question 8

The linked amino acid always has a free acid group at their end so other AA canbe added by the same reaction this is known as

Answer 8

Polypeptide

Question 9

What is polypeptide

Answer 9

When many amino acids are joined together by peptide bonds

Question 10

The breaking of a peptide bond using a water molecule is known as

Answer 10

Hydrolysis - reverse of condensation reactions

A reaction where 2 molecules joined by a condensation reaction are split apart again

Hydro- water required
Lysis- that a molecule is split apart

Question 11

Primary Structure

Answer 11

Sequence of amino acids on the polypeptide chain, it determines the rest of the protein structure

Question 12

Secondary Structure

Basic level of protein folding

Answer 12

Held together by hydrogen bonds between the carboxyl groups and the amino groups in the polypeptide backbone
a - helix. Alpha
B - sheet. Beta

Question 13

a -helix. Alpha

Answer 13

The poly chain is wound round to form a helix held together by hydrogen bonds running parrallel with the long helical axis
A very stable and string structure due to is many hydrogen bonds

Question 14

B - sheet. Beta

Answer 14

Zigzags back and forward forming a sheet.

Held together by hydrogen bonds.

Question 15

Protein structure has 4 levels

Answer 15

Primary structure
Secondary structure
Tertiary structure
Quaternary structure

Question 16

Tertiary structure

Answer 16

3 dimensional structure formed by the folding of a whole polypeptide chain. Held tog by bonds between the R groups of AA in the protein.

3 types of bonds involved
Hydrogen bonds
Ionic bonds
Sulphur bridges

Every protein has a tertiary structure responsible for its properties and functions

Question 17

Quaternary structure

Answer 17

Describes the spatial organisation of the chains

Only exists if they is more than 1 polypeptide chain present in a complex protein.

Question 18

Fibrous proteins

Answer 18

Made up of long molecules arranged to firm fibres (keratin). Several helices maybe wound each other to form very strong fibres

Question 19

Collagen

Answer 19

Fibrous protein stronger than steel
Consists of 3 polypeptides chains coiled round each other in a triple helix

Humans are largely held tog by collagen found in are bones, cartilage, tendons and ligaments.

Question 20

Summary
Primary protein structure - a sequence of a chain of amino acids
Secondary protein structure - occurs when the sequence of amino acids are linked by hydrogen bonds. alpha helix & beta sheets
Tertiary protein structure - occurs when certain attractions are present between alpha helices and beta sheets
Quaternary protein structure - is a protein consisting if more than 1 amino acid chain

Answer 20

A