Proteins 2

Question 1

Give some examples of modified types of proteins?

Answer 1

Glycoproteins

Lipoproteins

Metalloproteins

Question 2

What are glycoproteins?

Answer 2

Compound composed of protein and carbohydrates

Question 3

How to glycoproteins occur?

Answer 3

From a post-translational modificaiton where a sugar molecule binds via an amino acid in the protein

Question 4

What are some of the roles of glycoproteins?

Answer 4

Protein stabalisation

Affect solubility

Protein orientation

Signalling

Cell recognition

Question 5

What is the process of forming a glycoprotein called?

Answer 5

Glycosylation

Question 6

Where does glycosylation occur?

Answer 6

The endoplasmic reticulum and the golgi apparatus

Question 7

What are some examples of glycoproteins?

Answer 7

Immunoglobulins

Blood group determinants

Question 8

What are lipoproteins?

Answer 8

Proteins and lipids bonded together

Question 9

What is the function of lipid proteins?

Answer 9

Transport insoluble fat and cholesterol in the blood

Question 10

What are examples of lipoproteins?

Answer 10

High density lipoproteins (HDL)

Low density lipoproteins (LDL)

Question 11

What are metalloproteins?

Answer 11

Protein molecules with a bound metal ion

Question 12

What are some examples of metalloproteins?

Answer 12

Enzymes

Storage

Signilling

Transport

Question 13

What are the three structures of proteins?

Answer 13

Globular (varied function)

Fibrous (structural function)

Membranous (associated with cell or orangelle membrane)

Question 14

What are some examples of globular proteins?

Answer 14

Enzymes

Messengers (hormones)

Transporters

Stack of amino acids

Structural function such as actin or tubulin

Question 15

What are some examples of fibrous proteins?

Answer 15

Bone matrices

Muscle fibres

Tendons

Connective tissue

Question 16

What are some examples of membranous proteins?

Answer 16

Relay signal

Membrane transporter

Membrane enzyme

Cell adhesion molecule

Question 17

What is a specific example of a globular protein?

Answer 17

Haemoglobin

Question 18

How does haemoglobin operate?

Answer 18

Carries O₂

Haem group at the centre of each polypeptide chain binds to a moleucle of O₂

Composed of 4 units, so you can carry 4 molecules of O₂

Question 19

What does the binding of O₂ do to the shape of haemoglobin?

Answer 19

Changes its conformaiton which allows for more O₂ to bind easier

Question 20

What is cooperative binding?

Answer 20

When a molecules binds to a protein and makes it easier for other molecules to bind

Question 21

What is a specific example of a fibrous protein?

Answer 21

Collagen

Question 22

What is the structure of collagen?

Answer 22

Three polypeptide chains coil around each other

Held together by hydrogen bonds

Composed of repeated units (glycine - x - proline)_n

where x = alanine, hydroxyproline or lysine)

Question 23

What happens when collagen interacts with each other?

Answer 23

They form fibriles and increase strength

Question 24

What kind of receptors are present in all cells and what do they allow?

Answer 24

LDL receptors

They allow the internalisation of LDL which is then broken down in lysosomes

Question 25

What are 5 possible classes of LDL receptor mutations?

Answer 25

1. Class 1 - no receptor produced
2. Class 2 - receptor never reach the cell surface
3. Class 3 - receptor can’t bind to LDL
4. Class 4 - receptors don’t internalise on binding
5. Class 5 - receptors don’t release LDL