Enzymes

Question 1

What do anabolic reactions do

Answer 1

build up molecules e.g protein synthesis

Question 2

What do catabolic reactions do

Answer 2

break down molecules e.g digestion

Question 3

What are enzymes

Answer 3

globular proteins that act as catalysts

Question 4

Why are enzymes called biological catalysts

Answer 4

Because they are made of living cells

Question 5

What is the structure of an enzyme

Answer 5

Protein with tertiary structure
Hydrophillic R groups on the surface making it soluble
Particular sequence of amino acids
R groups determine shape and bonds that form

Question 6

What is the active site

Answer 6

specific 3D site which substrate binds to by weak chemical bonds

Question 7

what are the general characteristics of enzymes

Answer 7

speed up reactions
not used up
have a high turn over rate
only catalyse reactions that are energetically favourable

Question 8

what are the 3 sites of enzyme action

Answer 8

extracellular
intracellular in solution
intracellular membrane bound

Question 9

what is an example of an enzyme acting extracellular

Answer 9

enzymes secreted from cells in exocytosis

Question 10

what is an example of an enzyme acting intracellular in a solution

Answer 10

in solution inside cells e.g glucose breakdown in glycolysis

Question 11

what is an example of an enzyme acting intracellular membrane bound

Answer 11

attached to membranes e.g mitochondria in ATP formation

Question 12

what is the lock and key model

Answer 12

the active site and substrate are complementary to each other and it is a specific fit

Question 13

what is the lock and key model

Answer 13

the active site shape changes slightly to acomodate the substrate

Question 14

how do enzymes speed up the rate of reaction

Answer 14

they modify the substrate so that the reaction requires a lower activation energy
when substrate enters active site the molecules alters the shape so reactions can occur at lower temp

Question 15

what is activation energy

Answer 15

minimum energy required in a chemical system for a reaction to occur

Question 16

what is the first limiting factor in a reaction

Answer 16

the enzyme conc

Question 17

what is the limiting factor as the reaction carries on

Answer 17

the substrate conc

Question 18

how do you calculate rate of production

Answer 18

increase in mass divided by time

Question 19

how do you calculate % increase in mass

Answer 19

actual increase in mass divided by initial mass X100

Question 20

what is inactivation

Answer 20

reversible reduction of enzyme activity at low temp
insufficient energy to form E+S complexes

Question 21

what happens to enzymes over 40 degrees

Answer 21

denature due to increasing breaking hydrogen bonds and altering the enzymes tertiary structure

Question 22

what happens to enzymes at low temps

Answer 22

they become inactivated

Question 23

what happens to enzymes if PH is too high

Answer 23

it becomes neutralised by positive OH- charges

Question 24

what happens to enzymes if the PH is too low

Answer 24

the H+ ion attracts negative charges and neutralises them

Question 25

What is enzyme inhibition

Answer 25

the decrease in the rate of an enzyme controlled reaction by an inhibitor

Question 26

What does an inhibitor do

Answer 26

binds with the enzyme and stops it from forming an enzyme substrate complex

Question 27

What is the effect of substrate concentration on enzyme activities

Answer 27

the more substrate the more successful collisions and complexes formed

Question 28

What is the effect of enzyme concentration on activity

Answer 28

as enzyme concentration increases there are more active sites available so more complexes can form

Question 29

What is the effect of pH on enzyme activities

Answer 29

too High
Neutralised by excess OH-ions
Too low
The H+ions neutralise negative charges
Both of these disrupt ionic and hydrogen bonds which changes the shape of the active site

Question 30

How are enzymes immobilised

Answer 30

fixed trapped or bound on an inert matrix

Question 31

What materials can be used to immobilise an enzyme

Answer 31

sodium alginate beads or cellulose microfibrils

Question 32

How do immobilised enzymes work at higher temperatures and pH

Answer 32

It creates a microenvironment because trapping the molecule prevents the shape change that would denature the active site

Question 33

what is an example of an inhibitor being used and how does it work

Answer 33

lactose free milk
milk passed through a column with immobilised lactase
lactose binds to active site and is broken Down

Question 34

what are the advantages of immobilised enzymes

Answer 34

increased stability and function over a wide range of temperatures and pH
products not contaminated
enzymes easily recovered for reuse

Question 35

why do enzymes trapped in beads have lower rate of reactions

Answer 35

because as is inside bead so substrate has to diffuse
readily available to bind on a matrix