enzyme action

Question 1

what are enzymes

Answer 1

biological catalysts that speed up metabolic reactions in living organisms by raising activation energy
catalysts remain unchanged at the end of the reaction
small amount can catalyse conversion of large no of substrates into product

Question 2

turnover number

Answer 2

the number of reactions that an enzyme molecule can catalyse per second

Question 3

what type of protein is an enzyme

Answer 3

globular protein
soluble in water bc of hydrophilic nature of R groups in their aa

Question 4

why are enzymes important

Answer 4

to sustain life, chemical reactions must occur rapidly with the aid of enzymes

Question 5

what is the role of enzymes in anabolic reactions

Answer 5

build up/synthesise large polymers
e.g. cellulose/long protein molecules
catalyses reaction

Question 6

what is the role of enzymes in catabolic reactions

Answer 6

break down large organic molecules
e.g. disgestion of large organic molecule starch into monomer, release of energy during respiration
catalyses reaction

Question 7

how does enzyme function

Answer 7

both intra/extraceullarly

Question 8

example of an intracellular process

Answer 8

dna replication
dna polymerase, ligase
catalse, protects cell from damage by breaking down hydrogen peroxide to water and oxygen
4 polypeptide chains and a haem group, highest turnover number

Question 9

example of an extracellular process

Answer 9

digestion
amylase, produce in salivary glands, digest starch to maltose

Question 10

what is a metabolic pathway

Answer 10

series of consecutive reactions with each step being catalysed by a different enzyme, specific to substrate produced
cam be anabolic/catabolic
e.g. respiration, photosyntesis

Question 11

what happens when one enzyme cannot function

Answer 11

whole metabolic pathway cannot run

Question 12

what are metabolites

Answer 12

reactants, intermediaries, products

Question 13

what are oxidoreductases

Answer 13

enzymes that catalyses the transfer of electron during oxidation and reduction reactions

Question 14

transferases

Answer 14

the transfer of functional group from one molecule to another

Question 15

hydrolases

Answer 15

catalyses hydrolysis

Question 16

lyases

Answer 16

splitting of bonds

Question 17

isomerases

Answer 17

rearranging of molecule

Question 18

ligases

Answer 18

joining two molecules by forming covalent bonds

Question 19

general equation for enzyme-controlled reaction

Answer 19

enzyme + substrate –> enzyme-substrate complex –> enzyme product complex –> enzyme
+ product

Question 20

activation energy

Answer 20

energy to start the reaction

Question 21

how do enzymes increase the rate of a reaction

Answer 21

activation energy is transferred to break the bonds of reactants
enzyme lowers activation energy by creating a transition state between the enzyme and substrate that is more stable
if 2 substrate molecules need to be joined, attaching to enzyme holds them close together so they can bond more easily
if enzyme is catalysing a breakdown, fitting into active site puts a strain on the bonds in the substrate allowing molecule to break more easily

Question 22

what maintains the shape of the enzyme and active site

Answer 22

amino acids

Question 23

how does enzyme form

Answer 23

folding of sequence of amino acids

Question 24

lock and key hypothesis

Answer 24

substrate fits exactly into active site just like a key fitting a lock
held there with various bonds to form enzyme-substrate complex
1. substrate molecule is split into two or more products
2. more substrate molecules are joined together
complex only exists for a fraction of a second until the products are formed
products leave the active site and enzyme is free to take part in another reaction

Question 25

induced fit hypothesis

Answer 25

active site initially not an exact fit for the substrate

substrate moves into active site, forces between the two molecules, distort enzyme and active site
enzyme substrate complex forms
formation of complex lowers activation energy to form products
products leave the active site and enzyme return to shape

Question 26

cofactors

Answer 26

a small non-protein molecule attached to enzymes

Question 27

two types of cofactors

Answer 27

activators and coenzyme

Question 28

activators

Answer 28

inorganic groups that permanently bound to the enzyme and prosthetic group
iron zinc copper

Question 29

coenzymes

Answer 29

large organic molecules that bind temporarily to the enzyme transferring chemical groups that is necessary for reaction to occur
nad
vitamin b3, c

atp

Question 30

amylase as an example of cofactor

Answer 30

only digest starch if Cl- is present

Question 31

precursor activation

Answer 31

inactive enzymes
important bc some enzymes causes damage in their activated form
undergo a change in shape to be activated, by addition of a cofactor
precursor protein, apoenzyme before activation
holoenzyme after activation