Proteins

Question 1

what is amino acid

Answer 1

monomers from which proteins are made

Question 2

draw the general structure of amino acids

Question 3

what does the NH2 represent

Answer 3

amino group

Question 4

what does the COOH represent

Answer 4

carboxyl group

Question 5

what does R group represent

Answer 5

variable group ( 20 options of amino acids)

Question 6

describe how the amino acids are joined together to form a dipeptide

Answer 6

via a condensation recation
results in the release of water
a peptide bond is formed between the OH in carboxyl group and H in amino group

Question 7

what are proteins

Answer 7

polymers made up of the monomers amino acid

Question 8

what are the four levels of structure in protein

Answer 8

primary
secondary
tertiary
quaternary

Question 9

describe the primary structure

Answer 9

the order/sequence of amino acids in a protein

contains the initial sequence of amino acids and so therefore determine the proteins functions in the end

Question 10

describe the secondary structure

Answer 10

-the shape that the chain of amino acid makes into either

-alpha helix or beta pleated sheet

-hydrogen bonds hold the secondary structure
-hydrogen bonds formed between the C=O groups of the carboxyl group of one amino acid and H in the amino group of the second amino acid.

Question 11

when is a dipeptide formed

Answer 11

when two amino acids join together via a condensation reaction

Question 12

when is polypeptide formed

Answer 12

two or more amino acids join together via a condensation reaction

Question 13

what are proteins made of

Answer 13

one or more polypeptides

Question 14

when does hydrolysis happen

Answer 14

when the polypeptide and dipeptides are broken down

Question 15

describe the tertiary structure

Answer 15

-further folding of the secondary structure
-leads to form a unique 3D shape
-held in place by ionic , hydrogen and disulphide bridges

Question 16

where are the bonds formed in the tertiary structure

Answer 16

-ionic and disulphide bonds form between the R groups of different amino acids

-Disulphide bonds only sometimes occur as there must be a sulfur in the R groups for this bond to occur (e.g, S—S)

Question 17

compare and contrast the bonding in the secondary and tertiary structures of a protein(2)

Answer 17

both secondary and tertiary contains hydrogen bonds whilst tertiary further contains ionic and disulphide bridges

Question 18

explain why the tertiary structure of proteins is important for metabolic reactions (3)

Answer 18

-enzymes are proteins that catalyse biological reactions
-the tertiary structure affects the shape of the enzymes active site
the active site must be complementary to the shape of the substrate in order to catalyse the reaction.

Question 19

define the quaternary structure

Answer 19

(protein made up of more than one polpeptide chain held together by bonds )

Question 20

example of a quaternary structure

Answer 20

haemoglobin

Question 21

Haemoglobin is the oxygen-carrying molecule in red blood cells. At low pH, haemoglobin’s ability to bind to oxygen is reduced.

Suggest why a low pH affects haemoglobin in this way.

Answer 21

interfers with the bonds in the haemoglobin causing it to change shape
means it can no longer bind onto the oxygen

Question 22

describe the importance of the primary structure and its impact

Answer 22

if one amino acid in the sequence is different then it will cause the ionic, hydrogen / disulphide bonds to form in a diff location

Impact:
-Enzymes will have a different active site shape ( non functioning)
-carrier proteins will have a diff shaped binding site ( so molecules are no longer complementary + so cannot be transported across membranes