Main Topic 1: Biological molecules ( proteins)

Question 1

What are the monomers of proteins?

Answer 1

Amino acids.

Question 2

What is the general structure of a protein?

Answer 2

one amine group (H2N), one carbon in the middle, attached to a hydrogen, and also attached to a carboxyl group (COOH), and an R group.

Question 3

What is the R group in the protein represent?

Answer 3

A side chain

Question 4

How many common amino acids in all organisms are there?

Answer 4

20.

Question 5

what differenciaties every amino acid?

Answer 5

The side group(R group). The rest of the group, stays the same.

Question 6

What bond is formed between two amino acids?

Answer 6

Peptide bond

Question 7

what is a peptide bond?

Answer 7

A condensaion reacion between two amino acids, forms a peptide bond.

Question 8

What is a dipeptide?

Answer 8

Dipeptides are formed by the condensation of two amino acids.

Question 9

what is a polypeptide?

Answer 9

polypeptides are formed by the condensation of many amino acids.

Question 10

What are all the levels of a protein structure, in order?

Answer 10

Primary structure, secondary structure, tertiary structure, and quartenary structure.

Question 11

What is the primary structure? and what types of bonding does it have?

Answer 11

The sequence of amino acids in a polypeptide chain. Each amio acid is bonded to its neighbouring amino acid, through a peptide bond.

Question 12

What is the secondary structure? And what types of bonding does it have?

Answer 12

Folding of a polypeptide chain into a alpha-helix, or beta plated sheets. It involves hydrogen bonds.

Question 13

What are the two structure a folding in the secondary structure can make?

Answer 13

Alpha - helix sheet, and beta - plated - sheet.

Question 14

How does a hydrogen bond work?

Answer 14

side groups can form many bonds between oxygen and hydrogen. This is becaause hydrogen is positive, and oxygen is negative.

Question 15

What is the tertiary structure of a protein? And what are the bonds involved?

Answer 15

3D folding of the polypeptide chain. It involves hydrogen bonds, ionic bonds, and disulfide bridges between side groups.

Question 16

What is the quartenary structure of a protein?

Answer 16

The way the different polypeptide chains tangle around each other, is called the quartenary structure of a protein.

Question 17

What do you call a non protein part put in a protein?

Answer 17

A prostethic group.

Question 18

what do we call proteins that have a prostethic group?

Answer 18

Conjugated proteins.

Question 19

Explain how Haemoglobin is a conjugated protein.

Answer 19

Haemoglobin has 4 polypeptide chains, and 4 haem groups. Those Haem groups carry iron, so that oxygen can bind to them. Those Haem groups are NOT proteins.

Question 20

What are the two protein shapes?

Answer 20

Globular, and fibrous.

Question 21

Describe a globular protein, and provide an example.

Answer 21

Globular proteins form special “globe - like” proteins. One example would be Haemoglobin.

Question 22

What is a functional protein?

Answer 22

A protein that performs a particular metabollic function.

Question 23

What is a fibrous protein? And provide an example.

Answer 23

Fibrous proteins, form long and strong fibres.One example would be Collagen.

Question 24

What function does Collagen have?

Answer 24

It has a structural function.

Question 25

What will happe if you somehow affect the primary structure?

Answer 25

This will affect the folding of the secondary an tertiary strcuture. this in turn will change the way the polypeptide chains are tangles around each other, and will therefore change the quartenary structure as well.

Question 26

What would happen if you made the Ph around a protein more acidic?

Answer 26

It would affect the ionic bonds in the tertiary structure.The carboxyl group would gain H+ ions, and become neutral, therefore the ionic bond would break. SAME GOES FOR HYDROGEN BONDS.

Question 27

Why doesnt a change in PH affect disulfide bridges?

Answer 27

Because they have strong covalent bonds between them.

Question 28

What would happen if you made the Ph around a protein more alkaline?

Answer 28

It would reduce the availability of protons.

Question 29

describe how you would carry out a test for proteins.

Answer 29

I would use the Biuret test.
1. Add some of the food sample to the test tube, and add equal volume of sodium hydroxide solution.
2. add a few drops of biuret reagent to the test tube, and gently mix.
3. If the solution turn purple, then we have got a positive biuret test. If the solution remains blue, then we have a negative test( no proteins present).