Chapter 3: 3.7

Question 1

What are the structural properties of globular protein?

Answer 1

• Compact
• Water soluble
• Spherical in shape
• Hydrophilic R-groups on the outside - this makes these proteins soluble

Question 2

What roles is a globular protein involved in?

Answer 2

> Regulating many process that are necessary to life (e.g. chemical reactions)

Question 3

What type of protein is insulin?

Answer 3

Globular

Question 4

What is the function of insulin?

Answer 4

A hormone involved in regulation of blood glucose concentration

Question 5

What are conjugated proteins? Structure?

Answer 5

Globular proteins containing a non-protein component called a prosthetic group

Question 6

What are simple proteins?

Answer 6

Proteins without prosthetic groups

Question 7

Elaborate on prosthetic groups

Answer 7

• Different types
• Lipids can mix with proteins forming lipoproteins
• Carbohydrates can mix with proteins forming glycoproteins
• Metal ions + molecules from vitamins form prosthetic groups
• These are called cofactors when they’re needed for the protein to carry out its function
• Haem groups (containing an iron II ion) are an example of prosthetic groups

Question 8

What is haemoglobin?

Answer 8

Red, oxygen-carrying pigment founds in erythrocytes (red blood cells)

Question 9

What type of protein is haemoglobin?

Answer 9

Quaternary protein

Question 10

What are the structural properties of hemoglobin? How does these properties help it do its’ job?

Answer 10

> Made from 4 polypeptides

> Made up of 2 beta/alpha sub units

> Each sub-unit contains a prosthetic haem group

> The Iron ions present in haem group can combine reversibly with an oxygen molecule - this enables haemoglobin to transport oxygen

Question 11

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Answer 11

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Question 12

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Answer 12

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Question 13

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Answer 13

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Question 14

What is catalase? What type of protein is catalase?

Answer 14

1. Enzyme

2. Quaternary protein

Question 15

What is catalase made up of?

Answer 15

4 haem prosthetic groups

Question 16

What does the presence of iron II ions allow catalase to do?

Answer 16

Allows catalase to interact with hydrogen peroxide and speed up its breakdown

Question 17

What is hydrogen peroxide?

Answer 17

A common byproduct of metabolism

Damaging to cells if it accumulates - catalase prevents this from happening

Question 18

What do fibrous proteins tend to make?

Answer 18

Strong, long molecules NOT folded into 3-D shapes like globular proteins

Question 19

What are fibrous proteins made from? Explain why.

Answer 19

Long, insoluble molecules - due to the presence of a high proportion of amino acids with hydrophobic R-groups in their primary structures

Question 20

What do fibrous proteins contain?

Answer 20

Limited range of amino acids with small R-groups

Question 21

Describe the amino acid sequence in the primary structure of fibrous proteins. What does this lead to?

Answer 21

1. Repetitive

2. Leads to very organised structures

Question 22

Give examples of fibrous proteins

Answer 22

1. Keratin
2. Elastin
3. Collagen

Question 23

What is keratin?

Answer 23

A group of fibrous proteins

Question 24

Where is keratin found?

Answer 24

Hair
Skin
Nails

Question 25

What does keratin contain? What does this result in?

Answer 25

1. A high proportion of the sulfur-containing amino acid, cysteine
2. Many strong disulfide bridges forming strong, inflexible and insoluble materials

Question 26

How is globular protein formed?

Answer 26

Form when proteins fold into their tertiary structure with the hydrophobic R-groups on the amino acids kept away from the aqueous environment

Question 27

What are the two types of protein?

Answer 27

Fibrous and Globular

Question 28

What properties does Insulin need to have?

Answer 28

Need to be soluble so they can move in the bloodstream

Hormones need to fit into specific receptors on plasma membranes to have their effect so need to have a precise shape