Proteins

Question 1

How many different amino acids are there?

Answer 1

20

Question 2

what is the NH2 part of an amino acid called?

Answer 2

The amino group

Question 3

what is the COOH part of an amino acid called?

Answer 3

The carboxyl group

Question 4

What group in the amino acid changes depending on the amino acid

Answer 4

The R group

Question 5

What is the general composition of an amino acid

4

Answer 5

The amino group, carboxyl group, hydrogen atom & the R group

Question 6

What is the PH of the amino group?

Answer 6

It is basic and when the amino acid is exposed to a PH of 7, it can gain a hydrogen atom, becoming positively charged

Question 7

What is the PH of the carboxyl group?

Answer 7

It is acidic and when exposed to a PH of 7, it loses a Hydrogen atom, becoming negatively charged

Question 8

What happens when both groups are at a PH of 7?

Answer 8

They simultaneously become positively and negatively charged, now with the ion being called a ZWITTERION

Question 9

How do amino acids bond?

Answer 9

The amino group of one amino acid reacts with the carboxyl group of another and undergoes a condesation reaction, forming a PEPTIDE bond

Question 10

How can a dipeptide be written?

Answer 10

NH2-R1-R2-COOH (reverse if bonded the other way)

Question 11

What is the primary structure of proteins?

Answer 11

Proteins are made up of polypeptide chains, which are amino acids joined together with peptide bonds, with the unique sequence of amino acids making up proteins

Question 12

What is the secondary structure of proteins?

Answer 12

long protein chains that are organised into structures known as alpha-helix and beta-pleated sheets.

Question 13

How are secondary structures held together?

Answer 13

Through hydrogen bonding

Question 14

What does the alpha helix look like?

Answer 14

Twisted, 3D spiral with hydrogen bonds stabilising the structure

Question 15

What does the beta pleated sheets look like?

Answer 15

Strands of proteins that lie adjacent to one another, interacting laterally via H bonds between carbonyl oxygen and amino H atoms

Question 16

What is the tertiary structure?

Answer 16

It is the twisting and folding of alpha hellix’s and beta pleated sheets, giving a more compact, 3D structure

Question 17

What Bonds are involved in the tertiary structure?

Answer 17

• Disulphide interactions
• Hydrogen bonding
• Hydrophobic and Hydrophilic Interactions
• Ionic Bonding

Question 18

What is ionic bonding?

Answer 18

It is the attraction between positive and negative ions which have a strong electrostatic force of attraction.

Question 19

What is Disulphide interactions?

Answer 19

It i the covalent bonding between sulphur atoms

Question 20

What is Hydrophobic/phillic interactions?

Answer 20

They occur when in solution, with hydrophobic R groups orientating away from solution and hydrophillic going to the solution, creating strong folding

Question 21

What is the Quaternary structure?

Answer 21

The arrangement of more than one protein molecule in a multi-subunit complex.

Question 22

What are the molecules that make fibrous proteins insoluble?

Answer 22

They are long, thin molecules

Question 23

How are the polypeptides arranged in fibrous proteins?

Answer 23

They are parallel chains that cross link and form long fibres

Question 24

Why are fibrous proteins good in tendons?

Answer 24

They are strong and tough

Question 25

What does a single fibre consist of?

Answer 25

Three identical polypeptide chains, twisted around eachother, linked by hydrogen bonds, making it very stable

Question 26

What do globular proteins look like?

Answer 26

They are compact and folded into spherical molecules, making them soluble

Question 27

How many polypeptide chains are in globular proteins?

Answer 27

Four

Question 28

Give an example of a globular protein and what makes it distinctive?

Answer 28

Haemoglobin, which in the centre has iron containing haem groups