Transcript Enzymes - eduBuzz.org

Enzymes
The cell’s essential
molecules
The Importance of Enzymes
Enzymes are very special
protein molecules found in
the cytoplasm of cells
 They speed up reactions in
cells without the need for an
increase in temperature !

Enzyme Activity

Enzymes are found in both animal and
plant cells where they speed up reactions.
 They can speed up reactions which break
down large molecules into small ones.
 They also build small molecules together
to produce larger more complex
molecules.
An enzyme in
the cell’s
cytoplasm
splitting
a dangerous
substance into
two harmless
ones.
An Enzyme at Work
Enzymes and Temperature

Enzymes can only help reactions when they come
in contact with their substrates* (*substances
which join to enzymes)
 Molecules in a liquid move faster if they are
given more energy by heating the liquid.
 Enzymes and their substrates find each other
faster in warm liquids.
 Enzyme reactions are faster in warm liquids!
The graph below shows how enzyme reactions
speed up when warm, but go slowly when cold!
Rate of reaction with Temperature
14
Volume of
Oxygen
produced
(cms 3 )
12
10
8
6
4
2
0
5
10
15
20
Temperature °C
25
30
35
Enymes and Temperature
continued

Write down the following temperatures in
your jotters with a space between them.
10°C _____ 20°C ____ 30°C ______
 Find out the volume of oxygen produced by
the enzyme at each of these temperatures.
 Your teacher will now take you back to the
last slide.
The graph below shows how enzyme reactions
speed up when warm, but go slowly when cold!
Rate of reaction with Temperature
14
Volume of
Oxygen
produced
(cms 3 )
12
10
8
6
4
2
0
5
10
15
20
Temperature °C
25
30
35
Enzymes in Danger
• Enzymes are very complex protein molecules.
• When they come in contact with very high
temperatures they start to change shape.
• If their shape is changed they can no longer work
as enzymes !
• Acids and alkalis also damage these complex
molecules !
Effects of Temperature and Acids and Alkalis
Enzyme before treatment - a
complex protein.
After heat or contact with acid
the protein unravels and no
longer functions as an enzyme!
The enzyme is denatured.
More about Temperature and enzymes

The graph on the next slide shows the way in
which the activity of an enzyme changes with
temperature. Try to answer the following
questions about this graph in your jotter.
 What is happening:—
 1. To the activity between points A and B
 2. To the activity at point B
 3. To the activity between points B and C
 4. To the enzyme between points B and C
 5. Think carefully - why was no measurement
made at 0°C ?
This graph shows what happens to they way an
enzyme reacts over a range of temperatures !
Enzyme fact file
Copy the title of this slide. Then copy and complete and the
sentences below.
1. Enymes are protein molecules found in the …….?…. of cells.
2. Enzymes ….?…. ..?. reactions inside cells.
3. Enzymes can speed up reactions which:—
……?…. small molecules into larger ones.
……?…. …?… large molecules into small simple molecules.
4. Reactions which use enzymes can be speeded up by ……?…….
the ……?……. .
5. Enzymes do not function when …..?….. by …..?…. temperatures.
6. ….?…. and …..?….. also damage enzymes.
Word Bank
damaged; increasing; acids; temperature; speed up; cytoplasm;
break up; extreme; build; alkalis