2.2 Proteins

Question 1

What are globular proteins?

Answer 1

Proteins formed by compact amino acid chains, then folded into intricate chains that resemble spheres

Question 2

Are globular proteins soluble or insoluble in water?

Answer 2

Soluble

Question 3

Give an example of a globular protein and what it does:

Answer 3

Insulin, which is produced by the pancreas, it aids the bodies ability to regulate energy and metabolize sugars

Question 4

What does insulin illustrate?

Answer 4

A proteins ability to act as a biological messenger

Question 5

What else can proteins act as?

Answer 5

Biological transport mechanisms and they can play a role in the structure of animal cells

Question 6

What are conjugated proteins?

Answer 6

(Non-polypeptide) Proteins that function in interaction with other chemical groups

Question 7

What are conjugated proteins attached by?

Answer 7

They are attached by covalent bonds (weak interactions)

Question 8

Are conjugated proteins soluble or insoluble in water?

Answer 8

Soluble in water

Question 9

What are proteins?

Answer 9

Long chains of amino acids, they are a diverse group of large and complex molecules

Question 10

Give an example of conjugated proteins:

Answer 10

• haemoglobin

* catalase

Question 11

What are fibrous proteins?

Answer 11

A proteins with a elongated shape forming a rod or wire like shape

Question 12

What do fibrous proteins provide?

Answer 12

Structural support for cells and tissues

Question 13

Give examples of fibrous proteins:

Answer 13

• keratin
• elastin
• collagen

Question 14

Are fibrous proteins soluble or insoluble in water?

Answer 14

Insoluble

Question 15

What breaks down proteins?

Answer 15

Protease enzymes

Question 16

What is a prosthetic group?

Answer 16

A non protein component in globular proteins

Question 17

What are proteins without a prosthetic group called?

Answer 17

Simple proteins

Question 18

What is formed when a lipid and protein combine?

Answer 18

A lypoprotein

Question 19

What is a glycoprotein?

Answer 19

When a carbohydrate combines with a protein

Question 20

What is a COFACTOR?

Answer 20

A prosthetic group formed by metal ions and vitamins

Question 21

Give an example of a prosthetic group?

Answer 21

HAEM group - contain an iron ion

Question 22

What contains HAEM groups?

Answer 22

Catalase and haemoglobin

Question 23

What do protease enzymes break down?

Answer 23

Peptide bonds

Question 24

How does the protease enzyme denature the protein?

Answer 24

It breaks the bonds, altering the structure, it first breaks the hydrogen, then the ionic then the disulphide

Question 25

What changes in the structure of amino acids?

Answer 25

The R group changes, but all amino acids have the same general structure

Question 26

What are the four structures of proteins?

Answer 26

• primary structure
• secondary structure
• tertiary structure
• quaternary structure

Question 27

How many naturally occurring amino acids are there?

Answer 27

There are 20 naturally occurring amino acids each with their own R group

Question 28

How is a polypeptide chain formed?

Answer 28

When amino acids are added to a dipeptide

Question 29

How many polypeptides does one protein consist of?

Answer 29

One polypeptide

Question 30

What is polymerisation? And what type of reaction is this?

Answer 30

The process in which amino acid monomers are joined to form a polypeptide, this is a condensation reaction

Question 31

What are the types of proteins?

Answer 31

• structural
• catalytic
• signalling
• immunological

Question 32

What are structural proteins?

Answer 32

They are the main component of body tissues such as muscle, skin, hair and ligaments

Question 33

What are catalytic enzymes?

Answer 33

All enzymes are proteins catalysing many biochemical reactions

Question 34

What are signalling proteins?

Answer 34

Hormones and receptors (many of these are proteins)

Question 35

What are immunological proteins?

Answer 35

Antibodies are proteins

Question 36

Where is a disulphide bridge formed?

Answer 36

Between two cystine amino acids

Question 37

What does the primary protein structure look like? And what bond joined them?

Answer 37

A long chain of amino acids joined by polypeptide bonds

Question 38

What doe the primary structure of a protein determine?

Answer 38

It’s shape and function

Question 39

What are the two secondary structures?

Answer 39

• alpha helix

* beta pleated sheet

Question 40

What bond does the secondary structure contain?

Answer 40

Weak hydrogen bonds

Question 41

How are the weak hydrogen bonds form?

Answer 41

The positive charge on the hydrogen and the negative charge of the oxygen

Question 42

What do the hydrogen bonds cause in the secondary structure?

Answer 42

Causes the long polypeptide chains to twist into a 3D helix

Question 43

What is the tertiary structure?

Answer 43

The 3rd protein structure it is a further folded and twisted to give it a more complex 3D structure

Question 44

How is the tertiary structure maintained?

Answer 44

By a number of bonds

Question 45

What bonds are contained in the tertiary structure?

Answer 45

• disulphide bonds
• ionic bonds
• hydrogen bonds

Question 46

What are disulphide bonds?

Answer 46

Bridges formed between cystine they are strong and difficult to break

Question 47

What are ionic bonds?

Answer 47

Bonds formed between carboxyl and amino groups that are not involved in the formation of peptide bonds, they are weaker than disulphide bridges

Question 48

What are hydrogen bonds like?

Answer 48

They are numerous however they are weak and easily broken

Question 49

What is the bond between two amino acids?

Answer 49

A peptide bond

Question 50

How are peptide bonds formed?

Answer 50

The joining of amino acids by a condensation reaction