PROTEINS & ENZYMES

Question 1

what are proteins?

Answer 1

proteins are functional units of the cell

Question 2

what do proteins form?

Answer 2

enzymes, structural, transport, storage, signalling, receptors, gene regulation

Question 3

what links monomers to form polymers?

Answer 3

dehydration reaction - forming peptide bonds between 2 amino acid monomers

Question 4

how many amino acids make up a proteins?

Answer 4

20

Question 5

what determines the structure and function of the protein?

Answer 5

side-chain R of the protein

Question 6

what makes up a protein?

Answer 6

variable side chain (R group), Carboxyl group, Hydrogen atom and amino group

Question 7

how does protein name come about?

Answer 7

by the two primary functional groups

Question 8

how many essential and non-essential amino acid are there?

Answer 8

essential : 9 - cannot be synthesized by body

non-essential : 11 - can be synthesized by body

Question 9

what are the functional group?

Answer 9

gives the molecule the properties and are centres of chemical reactivity

Question 10

what are proteins composed of?

Answer 10

C, H, O, N & small amounts of other elements notably sulfur

Question 11

what are the level of structures?

Answer 11

primary, secondary, tertiary, quarternary

Question 12

what are primary structures?

Answer 12

linear order of amino acid joined together by as polypeptide

Question 13

what are secondary structures?

Answer 13

localised folding of linear polypeptide resulting in alpha helix or beta pleated sheet or random loop

Question 14

what are tertiary structures?

Answer 14

3d shape of a protein which closely links to its function

Question 15

what are quarternary structures?

Answer 15

made up of 2 or more subunits of proteins

Question 16

what are peptides and polypeptide?

Answer 16

peptide : 2 or more amino acids linked

polypeptide : chain of amino acids joined by peptide bonds

Question 17

what determines amino acid sequence?

Answer 17

the genes - number and sequences of amino acid vary in proteins

Question 18

what happens during secondary structure?

Answer 18

chemical and physical interactions causes the polypeptide chains to be folded or pleated into different shapes by hydrogen bonding between amino acids

Question 19

what r group interactions contribute to tertiary structure?

Answer 19

hydrogen, ionic, disulphide bonding, hydrophobic interactions and van der waal’s force

Question 20

what happens in quarternary structure?

Answer 20

the individual polypeptides join together to form a larger protein - all subunits must be present for protein to function

Question 21

what causes protein to denature?

Answer 21

pH or heat cause irreversible change in protein shape

Question 22

what are enzymes?

Answer 22

proteins which acts as a catalyst to speed up a chemical reaction

Question 23

what does enzymes have?

Answer 23

enzymes have an active site where the substrate binds

Question 24

what are substrates?

Answer 24

the molecules that an enzyme work on

Question 25

what can enzymes do?

Answer 25

either break a single structure or join two or more substrate molecules together

Question 26

what are the two mechanism of enzyme action?

Answer 26

lock and key - substrate must be compatible so that enzymes can modify the substrates
induced fit hypothesis - enzyme will mold itself to the shape of the molecule once the proper substrates makes contact with the enzyme

Question 27

properties of an enzyme?

Answer 27

• all enzymes are proteins
• speed up biochemical reactions
• very specific (substrate-specific)
• lowers activation energy by lowering energy barrier allowing the reactants to react faster forming the products
• not damaged during the reaction - can be reused

Question 28

what do some enzymes require?

Answer 28

cofactors - required in diet of organisms

Question 29

factors that affect the rate of enzyme reaction?

Answer 29

temperature - must hit optimum temp ; high temp breals the disulphide bonds holding the tertiary structure - DENATURED
pH - must reach optimum pH (5-9)
substrate concentration - directly proportional at the start and no effect nearing the end as all enzymes are working at max. rate
enzyme concentration - directly proportional all the way if substrates are in excess
enzyme inhibitors - active enzymes is prevented from combing with its substrate

Question 30

what type of enzyme inhibitors are there?

Answer 30

IRREVERSIBLE - Inhibitors are temporarily bound
REVERSIBLE - competitive and non-competitive
- Inhibitors bind permanently, permanently deactivating the enzyme

Question 31

competitive inhibition

Answer 31

inhibitor competes with the substrate for the active site

Question 32

non-competitive inhibition

Answer 32

inhibitor binds to the allosteric site and alters its shape