Enzymes

Question 1

metabolism

Answer 1

is the sum of all the chemical reactions in a cell or an organism.

Question 2

source of energy

Answer 2

solar energy

Question 3

solar energy

Answer 3

source of all living material through photosynthesis

Question 4

chemosynthetic

Answer 4

get their energy from chemical reactions

Question 5

cellular energy

Answer 5

stored and released by the cells

Question 6

enzymes

Answer 6

a protein biological catalyst

Question 7

Enzymes role in metabolism

Answer 7

1. control metabolic reactions

2. allow reactions to occur at a rate suitable to sustain life

Question 8

substrate

Answer 8

substance on which an enzyme works on

Question 9

enzyme is affected by

Answer 9

pH and temperature

Question 10

optimum (activity, pH, temperature)

Answer 10

. when an enzyme is working at its maximum rate

. the pH or temperature the enzyme works best at

Question 11

denatured

Answer 11

enzyme has lost its structure and can no longer function

Question 12

specific

Answer 12

only act on one particular substrate

Question 13

mechanism of enzyme activity

Answer 13

1. The Substrate binds to active site of enzyme
2. An Enzyme-substrate complex is now formed
3. The enzyme changes shape to fit better around the substrate
   [This is called Induced Fit]
4. The Product(s) are formed and then released.
5. The enzyme returns to its original shape ready to be used again

Question 14

Anabolic

Answer 14

Complex molecules are formed from simpler ones. Needs energy
examples : photosynthetic and protein synthetic

Question 15

Catabolic

Answer 15

Simpler products are formed from a more complex molecule Releases energy
example : digestion and respiration

Question 16

Effect of pH on the Rate of Catalase Activity

Answer 16

add to graduated cylinder
5g chopped celery
pH 4 buffer
one drop of washing up liquid
add 10cm3 of hydrogen peroxide using syringe
stand both in water bath at 25 degrees cellules
calculate rate enzyme activity
at 25 add substrate to enzyme
measure and record foam height per minute
repeat using different buffers 9, 13
A control using the same set-up, but do not add enzyme
.Results
a. Catalase activity varies with ph.
b. The most foam is produced at pH9 as this is the optimum pH for catalase activity
.c. At pH 4 and13 no foam is produced, as the enzyme catalase is denatured at these pH values.
d. At pH 7 and11 catalase did show activity, but produced less foam.

graph

Question 17

Effect of Temperature on the Rate of Catalase Activity

Answer 17

add to graduated cylinder
5g chopped celery
pH 9 buffer
one drop of washing up liquid
add 10cm3 of hydrogen peroxide using syringe
stand both in water bath at 0 degrees cellules
calculate rate enzyme activity
at 0 add substrate to enzyme
measure and record foam height per minute
repeat using different water baths 25 and 60
A control using the same set-up, but do not add enzyme
Results
a. Temperature does affect the rate of catalase activity
b. The optimum temperature for catalase is 25 C as most foam was produced
c. At 60 C –‘catalase was denatured’ as no foam was formed
d. At 0oC –‘catalase was inactive’, producing little/no foam. But increasing the temperature showed enzyme activity resume

graphs

Question 18

Effect of Heat Denaturation on the Activity of Catalase

Answer 18

denature enzyme by boiling at 100 C for 5mins.
add denatured enzyme to graduated cylinder with pH 9 buffer and one drop of washing up liquid
Add 10cm3 of hydrogen peroxide to test tube using syringe
Stand both the graduated cylinder and the test tube in a water bath at 25 C
Calculate the rate of enzyme activity
a. At 25 C , **add the substrate to the enzyme in the cylinder
b.Measure and record the foam height , per minute
prepare a control using same set up but leave the enzyme untreated
provide optimum conditions for both experiment and control

pH 9 buffer and 25 using water bath

results

a. experiment- no activity
b. control - foam is produced

Question 19

Bioprocessing

Answer 19

use of living organisms to make useful substances

Question 20

• Bioreactor

Answer 20

vessel in which products are made by cells (or organisms)

Question 21

• Immobilized

Answer 21

trapped in a gel or are fixed to each other

Question 22

1. Immobilizing the enzyme

Answer 22

1. Mix enzyme [yeast] with sodium alginate solution
2. Using a syringe drip this into calcium chloride solution
3. Beads form
4. Leave to harden for 10 minutes
5. Filter off beads using sieve and wash with distilled water

Question 23

Using the Immobilized Enzyme

Answer 23

add substrate sucrose to the immobilized enzyme in separating funnel.
enzyme sucrase in yeast will digest sucrose to form glucose
control - use free yeast in the same set up
results- test for glucose
open taps in each funnel and run some liquid in beakers
use clinistix to test for glucose in each beaker
repeat at 2 minute intervals until glucose appears turns purple
TURBIDITY - run remaining product from each and compare both

control free yeast - cloudy product not pure.
immobilized clear pure product

Question 24

Applications of Immobilized Enzymes

Answer 24

1. Making ethanol using yeast working on glucose

2. Using glucose isomerase [enzyme] to convert glucose [substrate] to fructose [product]

Question 25

Advantages of Enzyme Immobilization

Answer 25

a) Product easily recovered
b) Enzyme lasts longer
c) Easier to purify product

Question 26

Role of Adenosine Triphosphate (ATP)

Answer 26

a) Stores, transports and releases energy within the cell
b) Energy stored using the reaction ADP + P + energy = ATP
c) Energy is stored in the final P~P bond
d) Energy released using the reaction ATP = ADP + P + energy

Question 27

Role of Nicotinamide Adenine Dinucleotide (NAD)

respiration and photosynthesis

Answer 27

a) In respiration
• NAD+ traps and transfers electrons and hydrogen ions
• From Krebs Cycle to Cristae of mitochondria

b) In photosynthesis
• NADP+ picks up 2 e- to become NADP-
• NADP- picks up H+ to become NADPH
• It passes on the H+ and the e-s to reduce CO2 in the Dark Stage to produce carbohydrates

Question 28

sodium alginate

Answer 28

gel substance to trap the enzyme

Question 29

calcium chloride

Answer 29

make gel insoluble forms the beads