Chapter 2- Proteins

Question 1

Draw a condensation reaction of two amino acids

Answer 1

Do it

Question 2

What does the condensation reaction involve and what does it eliminate?

Answer 2

1) amine group (NH2) of one amino acid and the carboxyl group (COOH) of another
2) water is eliminated

Question 3

What bond is formed?

Answer 3

Peptide bond

Question 4

What is a dipeptide?

Answer 4

Is a molecule consisting of two amino acids linked by a peptide bond

Question 5

Because of the different R groups; the twenty amino acids are what?

Answer 5

Chemically diverse

Question 6

The ribosome can make peptide bonds between any pair of amino acids so it makes polypeptides what?

Answer 6

Diverse- as they can be linked together in any sequence giving a huge range of possible polypeptides

Question 7

The amino acid sequence of each polypeptide is stored in a codes form in what?

Answer 7

In the base sequence of a gene

Question 8

How do base sequence of genes store amino acids?

Answer 8

Use genetic code

Question 9

How many bases at needed to code for each amino acid?

Answer 9

3 codons (bases)

Question 10

A protein may consist of what?

Answer 10

A single polypeptide or more than one polypeptide linked together

Question 11

Give an example of polypeptides with 1, 2,3 and 4 polypeptides linked together

Answer 11

1) lysozyme - enzyme in secretion
2) integrin- membrane protein
3) collagen- structural protein in tendons, ligaments , skin etc
4) haemoglobin- transports protein in RBC

Question 12

The amino acid sequence determines what?

Answer 12

The three- dimensional conformation of a protein

Question 13

How is the three dimensional conformation of proteins stabilised?

Answer 13

By bonds between R groups of amino acids within the molecule

Question 14

When disrupted or broken the protein becomes what?

Answer 14

Denatured

Question 15

How does heat cause desaturation ?

Answer 15

Causes vibrations within the molecule which can break intermolecular bonds

Question 16

How does pH cause denaturation?

Answer 16

Changes the charge on the R group, breaking ionic bonds within the protein or causing New Ionic bonds to form

Question 17

Living organisms synthesise many different proteins with what?

Answer 17

A wide range of functions

Question 18

What 3 examples of the use of proteins?

Answer 18

1) Blood clotting- plasma proteins act as clotting factors that cause blood to turn from liquid to gel in wounds
2) transport of nutrients and gas - proteins in blood help transport oxygen, carbon dioxide, iron and lipids
3) cell adhesion- membrane proteins cause adjacent animal cells to stick to each other within tissues

Question 19

Name 6 examples of proteins

Answer 19

1) rubisco
2) insulin
3) immunoglobulin
4) rhodopsin
5) collagen
6) spider silk

Question 20

Outline function of rubisco

Answer 20

Shape and chemical properties of its active site allow it to catalyse the reaction that fixed carbon dioxide from the atmosphere, which provides the source of carbon from which all carbon compounds needed by living organisms can be produced

Question 21

Outline function of insulin

Answer 21

This hormone is produced as a signal to many cells in the body to absorb glucose and help reduce the glucose concentration of the blood

Question 22

Outline the function of immunoglobulin

Answer 22

Known as antibodies. They bind to antigens on bacteria or pathogens. Also causes a response such as actin as a marker to phagocytes that can engulf the pathogens

Question 23

Outline the function of rhodopsin

Answer 23

A membrane protein of rod cells of the retina

Question 24

Outline the function of collagen

Answer 24

Forms a mesh of fibres in the skin and in the blood vessel walls that resists tearing - gives ligaments and blood vessels their immense strength

Question 25

Outline function of spider silk

Answer 25

Used to make the webs that spiders live on - when first made it contains regions where the polypeptides forms parallel arrays

Question 26

What is a proteome ?

Answer 26

Is all the proteins produced by a cell; a tissue or an organism

Question 27

To find out how many different proteins are being produced what do scientists do?

Answer 27

Mixtures of proteins are removed and then separated by gel electrophoresis

Question 28

What is a genome?

Answer 28

Is all the different genes of a cell, tissue or organism

Question 29

Genomes of an organism are fixed m, why are proteomes variable?

Answer 29

Because different cells in an organism make different proteins

Question 30

The proteome of each organism is what?

Answer 30

Individual - because of small differences in the amino acid sequence of a protein

Question 31

What are amino acids linked together by and to form what?

Answer 31

By condensation reaction to form polypeptides