Chapter 3 Proteins

Question 1

What is the general structure of an amino acid?

Answer 1

COOH—R—NH2

Question 2

What part of proteins determine function?

Answer 2

The R groups of amino acids, which result into precise shapes

Question 3

What bonds amino acids together? What is formed and how is it reverse

Answer 3

Condensation to bond
Dipeptide to Polypeptide
Hydrolysis

Question 4

What is the primary structure of proteins?

Answer 4

The sequence of the amino acids

Question 5

What is the secondary structure of proteins?

Answer 5

When the chain of amino acids coils to form an alpha helix or beta pleated sheet, formed from hydrogen bonds between N & H and O & H.
If it is between every 4 amino acids = helix
If it is between every 6 amino acids= sheet

Question 6

What is the tertiary structure of proteins and how is it formed?

Answer 6

The folding of a secondary structure, to form a very precise 3D shape
It is formed due to interactions between R groups of amino acids which stick out

Interactions include:
Ionic Bonding
Hydrogen Bonding
Disulphide bridges
London Forces / Permanent dipole-dipole

Question 7

What are the uncoiled polypeptide chains called in a protein?

Answer 7

Amorphous regions

Question 8

What is the quaternary structure of proteins?

Answer 8

The association of two or more amino acid subunits/ polypeptide folded chain, due to London Forces/ Permanent Dipole…, Hydrophobic/ Hydrophilic interactions, Ionic Bonds, Hydrogen Bonds, Disulphide bridges

Question 9

What test is used to test for proteins?

Answer 9

Bierets
Pale blue to purple

Question 10

What is globular protein and describe how it formed?

Answer 10

Spherical shaped, soluble proteins
Protein folds in tertiary so the hydrophobic R groups are pointed inwards, kept away from the aqueous environment
Hydrophilic R groups on outside

Question 11

What is a simple protein? What is a conjugated protein?

Answer 11

Conjugated- globular protein containing a non-protein inorganic component called a prosthetic group
Simple Proteins- ones without a prosthetic group

Question 12

Describe the structure of haemoglobin and how it related to its function

Answer 12

Haemoglobin in a globular, quartenary protein with 2 alpha and 2 beta subunits. It is a conjugated protein contains four haem groups, which bind reversibly to oxygen
It is water soluble which is necessary when it is find in high concentrations in the cytoplasm
Can change shape

Question 13

Describe the structure of a name enzyme and function

Answer 13

Catalase is a quartenary protein with 4 haem groups. It’s function is to catalyse and speed up the break down of H2O2 a toxic product of metabolism , when it builds up

Question 14

What is a fibrous protein?

Answer 14

Long insoluble proteins which contain a high proportion of hydrophobic R groups. They are unreactive and very strong, and flexible. They normally have a repetitive base structure and then to make strong, long, unfolded proteins. They play a structural role such as protective with keratin and nails, or to give elasticity like elastin

Question 15

What is the function of Keratin?

Answer 15

Protective role
Used to help form tissues of nails, hair and outer layers of skin
Lots of disulphide bridges (with the number of these bonds determining flexibility). Lots of amino acid cysteine

Question 16

What is the function of elastin? Give an example

Answer 16

Quartenary protein made from many stretchy molecules called tropoelastin. Found in elastic fibres with other protein fibres. Gives flexibility when needed. E.g in Blood Vessels, and alveoli, so they can expand and return to normal size

Question 17

What is the structure and function of collagen?

Answer 17

Used in connective tissues and blood vessels
3 polypeptides wound in a long and string rope structure