Topic 2.4: Proteins

Question 1

Amino acids are joined together on the ribosome to form long chains called

Answer 1

polypeptides

Question 2

The covalent bond between the amino acids is called

Answer 2

a peptide bond

Question 3

Define primary structure of protein

Answer 3

The order of the amino acid sequence is called the primary structure and determines the way the chain will fold

Question 4

Define secondary structure of protein

Answer 4

Amino acid sequences will commonly fold into two stable configurations, called secondary structures

Question 5

Define tertiary structure of protein

Answer 5

The overall three-dimensional configuration of the protein is referred to as the tertiary structure of the protein

Question 6

Define quaternary structure of protein

Answer 6

Certain proteins possess a fourth level of structural organisation called a quaternary structure

Quaternary structures are found in proteins that consist of more than one polypeptide chain linked together

Question 7

When do alpha helices occur?

Answer 7

Alpha helices occur when the amino acid sequence folds into a coil / spiral arrangement

Question 8

When do beta-pleated sheets occur?

Answer 8

Beta-pleated sheets occur when the amino acid sequence adopts a directionally-oriented staggered strand conformation

Question 9

Define denaturation

Answer 9

a structural change in a protein that results in the loss (usually permanent) of its biological properties

Question 10

What two conditions can cause denaturation of proteins?

Answer 10

temperature and pH

Question 11

Define proteome

Answer 11

the totality of proteins expressed within a cell, tissue or organism at a certain time

Question 12

collagen and spider silk are examples of what type of protein function?

Answer 12

structure

Question 13

insulin and glucagon are examples of what type of protein function?

Answer 13

hormones

Question 14

immunoglobins are examples of what type of protein function?

Answer 14

immunity

Question 15

hemoglobin and cytochrome are examples of what type of protein function?

Answer 15

transport

Question 16

rhodospin are examples of what type of protein function?

Answer 16

sensation

Question 17

actin and myosin are examples of what type of protein function?

Answer 17

movement

Question 18

rubisco are examples of what type of protein function?

Answer 18

enzymes

Question 19

What are the two main classes of protein tertiary structure?

Answer 19

fibrous proteins and globular proteins

Question 20

Define fibrous proteins

Answer 20

Fibrous proteins are generally composed of long and narrow strands and have a structural role (they are something)

Question 21

Define globular proteins

Answer 21

Globular proteins generally have a more compact and rounded shape and have functional roles (they do something)

Question 22

What is the difference between fibrous proteins and globular proteins in terms of shape?

Answer 22

Fibrous: long and narrow

Globular: round/spherical

Question 23

What is the difference between fibrous proteins and globular proteins in terms of purpose?

Answer 23

Fibrous: structural

Globular: functional

Question 24

What is the difference between fibrous proteins and globular proteins in terms of acid sequence?

Answer 24

Fibrous: repetitive amino acid sequence

Globular: irregular amino acid sequence

Question 25

What is the difference between fibrous proteins and globular proteins in terms of durability?

Answer 25

Fibrous: less sensitive to changes in pH, temperature Globular: more sensitive to changes in pH, temperature

Question 26

What is the difference between fibrous proteins and globular proteins in terms of solubility?

Answer 26

Fibrous: generally insoluble in water Globular: generally soluble in water

Question 27

Collagen is an example of what type of protein (globular or fibrous)?

Answer 27

Fibrous protein

Question 28

Myosin is an example of what type of protein (globular or fibrous)?

Answer 28

Fibrous protein

Question 29

Fibrin is an example of what type of protein (globular or fibrous)?

Answer 29

Fibrous protein

Question 30

Actin is an example of what type of protein (globular or fibrous)?

Answer 30

Fibrous protein

Question 31

Keratin is an example of what type of protein (globular or fibrous)?

Answer 31

Fibrous protein

Question 32

Elastin is an example of what type of protein (globular or fibrous)?

Answer 32

Fibrous protein

Question 33

Enzymes is an example of what type of protein (globular or fibrous)?

Answer 33

Globular protein

Question 34

Hemaglobin is an example of what type of protein (globular or fibrous)?

Answer 34

Globular protein

Question 35

Insulin is an example of what type of protein (globular or fibrous)?

Answer 35

Globular protein

Question 36

Immunoglobulin is an example of what type of protein (globular or fibrous)?

Answer 36

Globular protein