Proteins

Question 1

What sort of molecule is made when two amino acids join together

Answer 1

Dipeptide

Question 2

What sort of molecule is formed when more than two amino acids bond together

Answer 2

Polypeptide

Question 3

What is made up by one or more polypeptides

Answer 3

A protein

Question 4

What is the general structure of an amino acid

Answer 4

A carboxyl group (-COOH), an amino group (-H2N), a hydrogen (-H) and a variable group (-“R”) all attached to a carbon atom (C)

Question 5

What part of the amino acid determines its characteristics and makes it different from others

Answer 5

The variable group

Question 6

What chemical elements do all amino acids contain

Answer 6

Carbon, oxygen, hydrogen and nitrogen

Question 7

What element do only some amino acids contain

Answer 7

Sulphur

Question 8

What bonds link amino acids to form di/polypeptides

Answer 8

Peptide bonds

Question 9

What sort of reaction is amino acid synthesis

Answer 9

Condensation

Question 10

What sort of reaction is breaking a peptide bond

Answer 10

Hydrolysis

Question 11

What is the primary structure of a protein

Answer 11

The sequence of amino acids in the polypeptide chain (one different amino acid here can change the structure of the entire protein)

Question 12

What is the secondary structure of a protein

Answer 12

The chain of the primary structure doesn’t remain straight. In the secondary structure hydrogen bonds form between nearby amino acids to make it coil into an alpha helix or fold into a beta pleated sheet

Question 13

What are the monomers of proteins

Answer 13

Amino acids

Question 14

What is the tertiary structure of a protein

Answer 14

The coiled/folded chAin is often coiled/folded even further. More bonds form between different parts of the polypeptide Chain. For proteins made from a single polypeptide chain the tertiary structure is their final structure

Question 15

What is the quaternary structure of a protein

Answer 15

Some proteins are made of several different polypeptide chains all Joined together by bonds, the quaternary structure is the way these are assembled together (eg haemoglobin is 4 polypeptide chains bonded together)

Question 16

What is computer modelling

Answer 16

A method of creating 3D interactive images of proteins (handy for investigating different levels of structure)

Question 17

What are the bonds in the primary structure

Answer 17

Peptide bonds between amino acids

Question 18

What are the bonds in the secondary structure

Answer 18

Hydrogen bonds between points (amino acids) on the polypeptide chain

Question 19

What are the bonds in the tertiary structure

Answer 19

Ionic interactions
Weak interactions between negative r groups and positive r groups on different parts of the molecule

Disulphide bonds
Whenever two molecules of the same amino acid cysteine come close together the sulphur atom in one cysteine bonds to the sulphur in the other

Hydrophobic/hydrophilic interactions
When hydrophobic r groups are close together they tend to clump together in the protein. This means hydrophilic r groups are more likely to be on the outside which affects the way the proteins folds up into its final structure

Hydrogen bonds
Weak bonds that form in many places between slightly positive hydrogen atoms and slightly negative charged atoms in other r groups on the polypeptide chain

Question 20

What are the bonds in the quaternary structure

Answer 20

Tends to be determined by the tertiary structure of the individual polpeptide chains being bonded together (therefore influenced by all the bonds in previous structures)

Question 21

Where are the hydrophilic r groups in a globular proteins? What properties does this give them? Why is this useful?

Answer 21

Pushed to the outside
Makes them soluble
Therefore easily transported in fluids

Question 22

What type of protein is haemoglobin and what does it do

Answer 22

Globular

Carries oxygen around the body in red blood cells

Question 23

WhatS a conjugated protein? Give an example

Answer 23

A protein with a non protein group attached called a prosthetic group. Haemoglobin has 4 called haem groups (they contain iron that the oxygen binds to)

Question 24

What type of protein is insulin and what does it do?

Answer 24

Globular protein
A hormone secreted by the pancreas that helps to regulate blood glucose levels
Solubility is important to be transported to areas that it acts in
It consists of two polypeptide chains that are bonded by disulphide bonds

Question 25

What type of protein is amylase and what does it do

Answer 25

Globular protein
An enzyme that catalyses the breakdown of starch in the digestive system
Made of a single chain of amino acids
Secondary structure is made of BOTH an alpha helix and a beta pleated sheet

Question 26

Main features of fibrous proteins

Answer 26

Insoluble
Strong
Fairly unreactive

Question 27

What are the three proteins (we need to know) and what do they do

Answer 27

Collagen- found in connective tissues such as bone, skin and muscle
Very strong
Minerals can bind to it to increase its rigidity (eg in bone)

Keratin- found in many external structures (hair skin nails feathers horns)
Can either be flexible (skin) or hard and tough (nails)

Elastin- found in elastic connective tissues such as skin large blood vessels and some ligaments
Elastic so allows tissue to return to original shape after being stretched