3.1.4 Proteins- 3.1.4.1 General Properties

Question 1

What proteins are vital in all living organisms?

Answer 1

Enzymes

Antibodies

Hormones

Question 2

Give the functions of these vital proteins ?

Answer 2

Holding your body together

Allowing you to move

Digest and absorb your food

Controlling your body chemistry

Fighting off diseases

Question 3

What are proteins ?

Answer 3

Large, complex molecules

Always contain carbon, hydrogen, oxygen and nitrogen

Some contain sulfur

Question 4

What are amino acids ?

Answer 4

Monomers from which proteins are made

Question 5

Explain an amino acid in terms of the formula ?

Answer 5

There is an amino group -NH2

There is an acid group -COOH

The R group is the only group that changes
20 different amino acids so 20 different R groups

If sulfur was present it would be here

Question 6

What is the test for proteins ?

Answer 6

Biuret test -> biochemical test to detect peptide bond

Question 7

Explain the test for proteins and results

Answer 7

Dissolve substance in water

Add biuret reagents

A colour change will be from blue to purple/ lilac

Question 8

What is the biuret reagent made from ?

Answer 8

Copper sulfate

Sodium hydroxide

Question 9

How are amino acids joined together and what do they form ?

Answer 9

Condensation reaction

Forming peptide bonds and water

Question 10

What are two amino acids joined together called ?

Answer 10

Dipeptide

Question 11

What are three amino acids joined together called ?

Answer 11

Tripeptide

Question 12

What are many amino acids joined together called ?

Answer 12

Polypeptide

Question 13

How many amino acids would a protein never be and why ?

Answer 13

Tripepetide = 3

Because proteins are made with one or more polypeptides

Question 14

How many amino acids is haemoglobin made with ?

What is it called ?

Answer 14

Polypeptide =4

Question 15

Why do we divide the structure of proteins into 4 levels ?

Answer 15

Because they are large, complex organic molecules

Question 16

What are the four levels proteins are divided in ?

Answer 16

Primary structure

Secondary structure

Tertiary structure

Quaternary structure

Question 17

Explain the primary structure of a protein

Answer 17

Sequence of amino acids

Sequence is the order in which the amino acids are added

Question 18

Explain the secondary structure of a protein

Answer 18

Shape formed when chain of amino acids become folded and cooled with hydrogen bonds
Most common structures alpha-helix and Beta-sheet

Question 19

Explain the tertiary structure of a protein

Answer 19

Overall shape of the amino acid chain- whole polypeptide

When in water, variety of forces combine to twist, fold and bend the polypeptide into its most stable shape

Question 20

Explain the Quaternary structure of a protein

Answer 20

Occurs when protein has more than one polypeptide chain