Topic 4 chapter 5 part 1 enzymes - biological catalysts

1. Topic 4: Chapter 5
EnzymesEnzymes –– Part 1Part 1
Biological
Biological
Catalysts
Catalysts

2. What are Catalysts?
• Substances which can alter or
speed up a chemical reaction,
• without itself being chemically
changed at the end of the reaction.
• Substances which can alter or
speed up a chemical reaction,
• without itself being chemically
changed at the end of the reaction.

3. CatalystsCatalysts
(A) Inorganic
• Iron – Haber process
• Vanadium (v) Oxide –
production of sulphuric
acid
• Manganese (IV) Oxide
(A) Inorganic
• Iron – Haber process
• Vanadium (v) Oxide –
production of sulphuric
acid
• Manganese (IV) Oxide
(B) Organic
• Digestive enzymes
• Metabolic enzymes
(B) Organic
• Digestive enzymes
• Metabolic enzymes

4. • Enzymes are biological catalysts
• which are mainly proteins that are produced
by living cells.
• Enzymes can be DENATURED by heating or
by changes in the pH of the solution
• E.g. Digestive enzymes,
Metabolic enzymes
(B) Organic Catalysts(B) Organic Catalysts

5. The function of enzymes
• How is energy released from sugar (glucose)?
• But how can our cells provide such high
temperatures during cellular respiration to
release energy from glucose??
Glucose + Oxygen  Carbon dioxide + Water + Energy
Strong Heat

6. The function of enzymes
Lower Activation EnergyLower Activation Energy
• Activation Energy: Energy required to start a
chemical reaction.
Activation Energy
with enzyme
Activation
Energy without
enzyme
Reactants (Substrate):
(Glucose + Oxygen)
Products:
(Carbon dioxide + water)
Energy
Time

7. Enzyme-Catalyzed ReactionsEnzyme-Catalyzed Reactions
(A) Synthesis of
complex substances
Anabolic Reactions
• Protein synthesis
• Photosynthesis
• Conversion of glucose
to glycogen
• etc…
(A) Synthesis of
complex substances
Anabolic Reactions
• Protein synthesis
• Photosynthesis
• Conversion of glucose
to glycogen
• etc…
(B) Breaking down of
complex substances
Catabolic Reactions
• Digestion
• Cellular Respiration
• Detoxification in the
liver and blood by catalase
• etc…
(B) Breaking down of
complex substances
Catabolic Reactions
• Digestion
• Cellular Respiration
• Detoxification in the
liver and blood by catalase
• etc…

8. Enzyme-Catalyzed Anabolic ReactionsEnzyme-Catalyzed Anabolic Reactions
Protein SynthesisProtein Synthesis
• Synthesis of proteins from amino acids in the
cytoplasm
PhotosynthesisPhotosynthesis
• Synthesis of sugar from carbon dioxide and water
Glycogen formationGlycogen formation
• Conversion of glucose to glycogen for storage.

9. Enzyme-Catalyzed Catabolic ReactionsEnzyme-Catalyzed Catabolic Reactions
DigestionDigestion
• Breakdown of complex food
substances to smaller, simpler,
more soluble and diffusible
substances.
• So that food can pass through the
cell membrane and be absorbed into
the bloodstream.
• Enzymes involved – Hydrolases
(e.g Carbohydrases, Proteases and Lipases)

10. Enzyme-Catalyzed Catabolic ReactionsEnzyme-Catalyzed Catabolic Reactions
Cellular RespirationCellular Respiration
• Oxidation of glucose by cells to release
energy.
• Many enzymes
involved

11. Enzyme-Catalyzed Catabolic ReactionsEnzyme-Catalyzed Catabolic Reactions
Detoxification in the liver and bloodDetoxification in the liver and blood
• Conversion of toxic to non-toxic substances
• Example: Conversion of toxic Hydrogen peroxide,
H2O2 (a by-product of cellular respiration) to non-
toxic water and oxygen by enzyme CATALASE

12. Classification of enzymes
HydrolasesHydrolases
• Enzymes that catalyzes hydrolytic
reactions which involves the
addition of water molecules to
breakdown a complex molecule
• Examples of hydrolytic reactions:
 Digestion of carbohydrates,
proteins & fats

13. Classification of enzymes
HydrolasesHydrolases
Types of
Hydrolases
Example(s) Substrate
Carbohydrases Salivary and pancreatic amylase Starch
Cellulase produced by some
bacteria
Cellulose
Proteases Pepsin produced in the stomach Proteins
Trypsin produced as an inactive
form (trypsinogen) by the pancreas
Proteins
Erepsin produced by intestinal
glands
Polypeptides
Lipases Pancreatic and Intestinal lipases Fats

14. Classification of enzymes
Oxidation-Reduction EnzymesOxidation-Reduction Enzymes
• Enzymes that
are involved in
cellular
respiration.
• Breaks down
glucose to
release energy,
carbon dioxide
and water

15. 15
Test yourself
With questions in
Textbook Page 75

16. 16
Test yourself – pg 75 - answers
1
An enzyme is a biological
catalyst made of protein. It
alters the rate of a chemical
reaction without itself being
chemically changed at the end
of the reaction.

17. 17
Test yourself – pg 75 - answers
2
Yes, the statement is valid. Large,
insoluble molecules such as
carbohydrates, fats and proteins
cannot diffuse through the cell
surface membrane. They must first
be converted into simpler, smaller
substances, which are soluble and
diffusible.

18. 18
Test yourself – pg 75 - answers
3
Meat contains mostly proteins,
hence we can infer that this
enzyme acts on proteins. The
enzyme could soften meat by
breaking down the proteins into
peptides or amino acids.

19. 19
Test yourself – pg 75 - answers
4
A very rapid, violent chemical
reaction would take place, with
a thick layer of foam produced.
Water and oxygen are produced
when catalase in the red blood
cells breaks down hydrogen
peroxide.