Protein Structure And Types

Question 1

The sequence of amino acids in a polypeptide chain is called the […] structure of a protein

Answer 1

Primary

Question 2

In a polypeptide there is always one end with a free amino group called the […] and one with a free carboxyl group called the […]

Answer 2

N-terminus, C-terminus

Question 3

When does a proteins secondary structure form

Answer 3

When a chain of amino acids coils to form an alpha helix or folds into a beta pleated sheet

Question 4

What bonding between the amine and carboxyl groups is needed for the proteins secondary structure to form

Answer 4

Hydrogen bonding

Question 5

What happens for the protein to form it’s tertiary structure

Answer 5

The secondary structures fold up to form a precise 3D structure

Question 6

What R group interactions are in the tertiary structure as

Answer 6

Hydrophobic and hydrophilic interactions (weak interactions between polar and non-polar R-groups, no actual bonds)

-Hydrogen bonds (weakest of the bonds formed)

-Ionic bonds (form between oppositely charged R-groups)

-Disulphide bonds/bridges (covalent bonds and the strongest, only form if the R-group contains sulfur atoms)

Question 7

What can split the hydrogen bonds in the tertiary structure

Answer 7

High temperatures / altered pH

Question 8

How do quaternary structure proteins form

Answer 8

Because of the interactions of the tertiary structures of the different subunits

Question 9

What are multiple polypeptide chains called

Answer 9

Subunits

Question 10

Haemoglobin is an example of a […] protein with a […] structure

Answer 10

globular, quaternary

Question 11

Summary of each type of structure found in proteins

Answer 11

• The primary structure of a protein is the sequence of amino acids, joined by peptide bonds

• The secondary protein structure occurs when the sequence of amino acids are linked by hydrogen bonds in an alpha helix or beta pleated sheets

• The tertiary structure describes the folding of a polypeptide chain that result from the molecular interactions among the R groups of the different amino acids (H, disulphide, ionic bonds)

• The arrangement of two or more polypeptide chains in a protein make up its quaternary structure

Question 12

Properties of globular properties

Answer 12

• compact
• water soluble
• roughly spherical in shape

Question 13

How come globular proteins are water soluble

Answer 13

In their tertiary structure they fold so their hydrophobic R-groups are kept away from the aqueous environment, and the hydrophilic R-groups are on the outside in the aqueous environment

Question 14

What are conjugated proteins

Answer 14

globular proteins that contain a non-protein component called a prosthetic group

Question 15

Lipids combined with proteins =

Answer 15

Lipoproteins

Question 16

Carbohydrates combined with proteins =

Answer 16

Glycoproteins

Question 17

Metal ions and vitamins can also form […] groups

Answer 17

Prosthetic

Question 18

Fibrous proteins characteristics

Answer 18

• tend to make strong long molecules which don’t fold into complex three dimensional shapes like globular proteins

Question 19

Why do fibrous proteins have organised structures (due to…)

Answer 19

• Fibrous proteins being formed from long insoluble molecules
•This is due to the presence of a high proportion of amino acids with hydrophobic R-groups in their structure
•The amino acids sequence in the primary structure is usually quite repetitive, therefore it’s organised

Question 20

Function of globular proteins

Answer 20

• acting as enzymes
• messengers
• transport molecules
  -acting as hormones

Question 21

Function of conjugated proteins

Answer 21

Provide structure and support for cells

Question 22

Whats a prosthetic group

Answer 22

A non-amino acid unit e.g sugar or a nucleic acid

Question 23

Haemoglobin is made from […] polypeptides, […] alpha and 2 […] subunits

Answer 23

4, 2, beta

Question 24

Each haemoglobin subunit contains a […] group

Answer 24

Prosthetic haem

Question 25

What enables haemoglobin to transport oxygen around the body

Answer 25

The iron (II) ions present in the haem group are each able to combine reversibly with an oxygen molecule

Question 26

Fibrous proteins characteristics

Answer 26

• long, insoluble molecules
• organised structures
• not 3D shapes

Question 27

Why are fibrous proteins insoluble

Answer 27

Due to the presence of a high proportion of amino acids with hydrophobic R groups in their primary structures

Question 28

Examples of fibrous proteins

Answer 28

Keratin, elastin, collagen

Question 29

Function of fibrous proteins

Answer 29

Provides structural strength due to presence of many hydrogen bonds which results in great tensile strength