Proteins

Question 1

What elements are present in all proteins?

Answer 1

Carbon, hydrogen, oxygen and nitrogen

Question 2

What are the monomer units that make up a protein?

Answer 2

Amino acids

Question 3

Draw the structure of an amino acid.

Answer 3

Question 4

What are the bonds called that join amino acids together?

Answer 4

Peptide bonds

Question 5

In what type of reaction is a peptide bond formed?

Answer 5

Condensation reaction

Question 6

What is a polypeptide?

Answer 6

Many amino acids joined together by peptide bonds

Question 7

Describe exactly how amino acids are joined by peptide bonds in terms of the atoms?

Answer 7

The hydroxyl group of 1 amino acid reacts with a hydrogen in the amine group of another amino acid. This forms water.

Question 8

What group makes each amino acid different?

Answer 8

R-group

Question 9

What is it that causes proteins to have different structures?

Answer 9

Different sequences of amino acids leads to different structures with different shapes.

Question 10

What bond holds together the primary structure of a protein?

Answer 10

Peptide bonds

Question 11

Describe the primary structure of a protein?

Answer 11

Amino acids are joined in a polypeptide chain by polymerisation.

Question 12

What bond holds together the secondary structure of a protein?

Answer 12

Hydrogen bonds

Question 13

There are two ways the chains arrange themselves in the secondary structure of a protein. What are they?

Answer 13

Alpha helix and beta pleated sheet

Question 14

Describe the tertiary structure of a protein

Answer 14

The folded/coiled amino acid chains are coiled and folded into their final structure.

Question 15

What bonds hold together the tertiary structure of a protein?

Answer 15

Hydrogen bonds, ionic bonds and disulphide bonds/bridges

Question 16

Which is the weakest bond in proteins?

Answer 16

Hydrogen bonds.

Question 17

Which is the strongest bond in proteins?

Answer 17

Disulfide bond.

Question 18

What is the quaternary structure of a protein?

Answer 18

The final 3D structure of a protein.

Question 19

Where are proteins made in the cell?

Answer 19

The cytoplasm

Question 20

Name the 3 types of proteins

Answer 20

Globular, conjugated and fibrous

Question 21

Name 3 properties of globular proteins

Answer 21

Compact. Water soluble. Slightly spherical shape.

Question 22

What makes globular proteins soluble?

Answer 22

Hydrophobic R-groups are folded away from aqueous environment and hydrophilic R-groups are folded on the outside of the protein.

Question 23

Give an example of a globular protein.

Answer 23

Insulin.

Question 24

What is the difference between conjugated protein and simple proteins?

Answer 24

Conjugated proteins have a non protein component called a prosthetic group. Simple ones don’t.

Question 25

Finish the sentences. 1) Lipoproteins are made when ______ combine with proteins. 2) _______ are when carbohydrates combine wthe proteins.

Answer 25

1) Lipids 2) Glycoproteins

Question 26

Name 2 conjugated proteins.

Answer 26

Haemoglobin. Catalase.

Question 27

Describe the structure of fibrous proteins.

Answer 27

Strong, long molecules with repetitive primary sequence.

Question 28

Name 3 fibrous proteins.

Answer 28

Keratin. Elastin. Collagen

Question 29

What makes keratin so strong?

Answer 29

Amino acids with R-groups containing sulfur create disulfide bridges (really strong)

Question 30

How is elastins structure related to its function in blood vessel walls?

Answer 30

Made from stretchy molecules called tropoelastin so it can stretch without breaking. Important for blood flow at high pressure.

Question 31

Where is collagen found?

Answer 31

A connective tissue found in skin, tendons, ligaments.

Question 32

What denatures a protein?

Answer 32

Changes in temperature, salt or pH concentration can all denature a protein

Question 33

What happens to fibrous proteins when denatured?

Answer 33

They lose their structural strength.

Question 34

What happens to globular proteins when denatured?

Answer 34

They become insoluble and inactive.

Question 35

What is catalase?

Answer 35

An enzyme that catalyses the breakdown of hydrogen peroxide in the body which is harmful to us.