Topic 1: Proteins

Question 1

True or false: proteins are the most important biological molecule for living organisms

Answer 1

False-after water, proteins are the next major biological molecule in living organisms

Question 2

What monomers make up proteins?

Answer 2

Amino acids

Question 3

What chemical elements do amino acids contain?

Answer 3

Carbon,hydrogen,oxygen and nitrogen
Some amino acids contain sulphur

Question 4

Name the 4 different components that make up amino acids

Answer 4

1. Amine group
2. Carboxyl group
3. Carbon-containing side chain or R group
4. Hydrogen atom

Question 5

How many types of amino acids are there in the body?

Answer 5

20

Question 6

What makes amino acids different from each other?

Answer 6

The R groups

Question 7

What is the bond between amino acids called?

Answer 7

Peptide bond

Question 8

What is formed when 2 amino acids are joined together?

Answer 8

Dipeptide

Question 9

What is it called when dipeptide or more than 2 amino acids join together?

Answer 9

Polypeptide

Question 10

What are the 4 different levels of protein structure in order?

Answer 10

Primary
Secondary
Tertiary
Quaternary

Question 11

What controls the structure of different proteins?

Answer 11

Genes

Question 12

What is the structure of a protein determined by?

Answer 12

The number and position of amino acids

Question 13

What is the primary structure?

Answer 13

The sequence of amino acids
When many amino acids join together by condensation reactions to form a polypeptide chain

Question 14

What can happen as a result of changes in the amino acid sequence (primary structure)?

Answer 14

Changes in the tertiary structure which can affect its ability to function

Question 15

Why can changes in the primary structure affect the tertiary structure of a protein, and its ability to function?

Answer 15

Bonds that form between R groups of different amino acids form in different places

Question 16

True or false: all proteins are made of a singular polypeptide chain?

Answer 16

False: some may be a singly polypeptide chain but most are made up of more than one

Question 17

How is the secondary structure of proteins formed?

Answer 17

When hydrogen bonds form between amino acids

Question 18

In secondary structure, hydrogen bonds form. Give an example of where the bonds form and why

Answer 18

Between the amine group and the carboxylic acid group
Because the amine group is negatively charged and the carboxyl group is positively charged

Question 19

What structures are produced in secondary structure as a result of hydrogen bonding?

Answer 19

Alpha helix or beta pleated

Question 20

How is tertiary structure formed?

Answer 20

By interactions between the R groups of amino acids

Question 21

Secondary structure can result in alpha helices or beta pleated. What happens to alpha helices in tertiary structure?

Answer 21

They can be twisted and folder further to create more complex and unique 3D structures

Question 22

How are tertiary structures maintained?

Answer 22

By different bonds forming between the R groups

Question 23

What bonds can form between R groups in tertiary structures?

Answer 23

Hydrogen bonds, ionic bonds, disulphide bridges

Question 24

Where do ionic bonds form in tertiary structure?

Answer 24

Between carboxyl groups and amino groups
They aren’t involved in a peptide bond

Question 25

Describe how easily the bonds in tertiary structure can be broken

Answer 25

Hydrogen bonds- numerous but easily broken
Ionic bonds- weaker than disulphide bridges and can be easily broken by changes in PH
Disulphide bridges- strong so aren’t easily broken

Question 26

What is formed as a result of more bonds in tertiary structure?

Answer 26

Hydrophobic and hydrophilic regions

Question 27

What does tertiary structure mean for proteins that are made from a single polypeptide chain?

Answer 27

Tertiary structure forms their final 3D structure, they don’t have quaternary structure

Question 28

Why is the tertiary structure important?

Answer 28

It forms the specific shape of the protein e.g. enzyme active site, due to the bonding between the R groups of different amino acids

Question 29

What is the quaternary structure of proteins?

Answer 29

The protein structure when more than one polypeptide chains are combined together and bonds are formed between them

Question 30

Give 3 examples of proteins with quaternary structure

Answer 30

Haemoglobin
Antibodies
Protein receptors

Question 31

What are the 2 kinds of proteins?

Answer 31

Fibrous and globular

Question 32

What are fibrous proteins?

Answer 32

Fibrous proteins that have polypeptides that join together to form long fibres or sheets
They consist of long chains running parallel to one another and are held together by cross-bridges

Question 33

What is the main function of fibrous proteins and can you describe a property of them

Answer 33

• structural function
  -strong and are insoluble in water

Question 34

Give 2 examples of fibrous proteins and where they are found in the body

Answer 34

Keratin: fingernails and hair
Collagen: skin,bone,blood vessels and teeth, it is found in tendons which join muscles to bones

Question 35

Describe each structure level of the fibrous protein: Collagen

Answer 35

Primary- amino acids join to = polypeptide chain
Secondary- alpha-helix
Tertiary- alpha-helix is twisted to form a second helix
Quaternary- three similar polypeptides are wound together like rope which gives molecule the strength

Question 36

How are globular proteins different to fibrous?

Answer 36

-have a more spherical shape rather than long sheets
-biochemical function not structural
-they are soluble in water

Question 37

Give 3 examples of globular proteins

Answer 37

-enzymes
-channel proteins in cell membranes
-haemoglobin