Transcript enzymes - onlinebiosurgery

BIOLOGICAL CATALYSTS
FIND THE LINK…
What do these images of
• a feeding flesh fly
• a flashing firefly!
• biological washing powder
• a jar of baby food
have in common?
……ENZYMES !
A. Biological washing
powders contain
hydrolytic enzymes to
digest stains and clean
our clothes.
C.
Light is created when oxygen
combines with a substance called
luciferin in the presence of the
enzyme luciferase. The rhythm
and intensity of the flashes serve
to identify males and females to
each other.
B.
A flesh fly vomits digestive
juices, enzymes, and saliva on a
decaying caterpillar carcass
which begins to break down and
dissolve it. The fly can then
suck up the liquid food with its
mouth parts.
D. Enzymes are used to ‘pre-digest’
some of the larger food
molecules in baby food making it
easier for a baby’s digestive
system to function.
PROPERTIES OF ENZYMES
• enzymes are biological catalysts
controlling the chemical reactions that
take place in all our body cells
• they speed up reactions but do not get
used up themselves
• they are protein molecules made up of
long chains of amino acids
• they are folded to produce a special
shape vital for their function
How do enzymes work?
• The molecules that react in the enzyme-catalysed
reaction are substrates
• Molecules produced in the reaction are products
• The active site is the part of the enzyme where the
substrate fits and product forms
• Just like a key only fits into a specific lock, each
enzyme has its own specific substrate.
• Once the reaction is complete and the required
product has been produced, the enzyme is free to bind
with more molecules of substrate.
• Each enzyme can be used many thousands of times.
Lock and Key Hypothesis
Induced Fit Hypothesis
(this is extension work)
• This is similar to the ‘lock and key’ but it is thought that
the enzyme changes shape slightly as substrate binds
i.e. hand fitting into a glove
Factors affecting enzyme action
• Temperature
• pH
• Enzyme concentration
• Substrate concentration
Factors affecting enzyme action
•
Temperature is important in all reactions. As the temperature
increases, so does the rate of reaction. This is because heat energy
causes more collisions between the particles in the enzyme and
particles in the substrate.
•
Very high temperatures damage or denature enzymes.
•
Different enzymes work best at different pH values.
•
The optimum pH for an enzyme depends on its site of action. For
example, enzymes in the stomach have an optimum pH of about 2
because the stomach is acid, but intestinal enzymes have an optimum pH
of about 7.5.
•
Enzyme concentration. The more enzyme molecules, the more active
sites for substrate molecules to react and make more products
•
Substrate concentration. The more substrate molecules to react, the
more product can be made
MEASUREMENT OF CARBON DIOXIDE
1.
2.
3.
4.
5.
What is the purpose of the potassium hydroxide solution?
What does the indicator solution in flask B show?
How can you explain the change in flask D?
Suggest a suitable control investigation and explain your
choice.
Suggest any visible change that might happen in flask C.
Explain your answer.
To maintain a steady body
temperature in colder
surroundings in mammals
and birds
To enable muscles to
contract in animals
USES of
RELEASED
ENERGY from
RESIPIRATION
To build up larger
molecules using smaller
ones
To build up sugars,
nitrates and other
nutrients into amino acids
which are then built up
into proteins in plants
Human Digestive System
Can you name parts A-K?
A
K
B
C
J
I
D
H
E
G
F
Human Digestive System
Now Annotate each label
oesophagus
Parts of the Digestive System
•
•
•
•
•
•
•
•
•
•
•
A Mouth
B Liver
C Gall Bladder
D Large intestine
E Appendix
F Anus
G Rectum
H Small intestine
I Pancreas
J Stomach
K Oesophagus
•
•
•
•
•
Function of parts of the Digestive System
A
B
C
D
E
• F
• G
• H
• I
• J
• K
Mouth -food is ingested and mixed with saliva
Liver-produces bile which neutralises food, emulsifies fat
Gall Bladder-stores bile
Large intestine-reabsorbs water
Appendix-no known function in humans
Other animals?
Anus –exit for undigested food (faeces)
Rectum –stores undigested food (faeces)
Small intestine
- in the first part semi-liquid food is mixed with
pancreatic juice & bile
- in the second part digested food is mixed with
intestinal juice & absorbed into the blood
Pancreas – produces pancreatic juice (containing
enzymes, mucus & hydrogen carbonate ions)
Stomach – food mixed with acidic digestive juices
Oesophagus – carries food from mouth to stomach
Using which method?
Types of enzyme
1.
•
•
2.
Enzymes can either be
extracellular or
intracellular
Digestive enzymes are extracellular
enzymes - they control reactions that take
place outside cells.
3. Those enzymes which control reactions inside
cells are called (not surprisingly!) intracellular
enzymes e.g. enzymes in respiration and
photosynthesis
1.
MODEL GUT EXPERIMENT
What is the test for
Starch and Glucose?
2. What part does the
visking tubing play?
3. Can you predict the
results of this
experiment?
4. Justify your prediction.
ROLE OF DIGESTIVE ENZYMES
Copy and complete the table
ENZYME
AMYLASE
(a carbohydrase)
PROTEASE
LIPASE
PRODUCTION
SITE
SUBSTRATE
PRODUCT/S
AND WHERE
DIGESTION
TAKES PLACE
CONDITIONS
ROLE OF DIGESTIVE ENZYMES
ENZYME
AMYLASE
(a carbohydrase)
PROTEASE
LIPASE
PRODUCTION
SITE
Salivary
Glands
Pancreas
Small Intestine
Stomach
Small Intestine
Pancreas
Small Intestine
SUBSTRATE
STARCH
PROTEIN
LIPIDS
(FATS & OILS)
PRODUCT/S
AND WHERE
DIGESTION
TAKES PLACE
CONDITIONS
SUGARS in
mouth &small
intestines
ALKALINE
# no digestion
takes place in
the pancreas #
AMINO ACIDS
in stomach &
small
intestines
Stomach
produces
Hydrochloric
ACID
Fatty acids
Glycerol in
small
intestines
Bile produced
(by liver)
neutralises
stomach acid
to ALKALINE
conditions in
small intestines
MAKING USE OF ENZYMES IN THE HOME & INDUSTRY
ENZYME
Protease
Lipase
Carbohydrase
Isomerase
Example
WHAT DOES THE ENZYME DO?
MAKING USE OF ENZYMES IN THE HOME & INDUSTRY
ENZYME
Example
WHAT DOES THE ENZYME DO?
Protease
Used to pre-digest proteins during
the manufacture of baby foods
Lipase
Used (together with protease) in
biological detergents to digest the
food stains into smaller, water
soluble substances
Carbohydrase
Used to convert starch syrup, which
is relatively cheap, into sugar syrup,
which is more valuable - for
example as an ingredient in sports
drinks
Isomerase
Used to convert glucose syrup into
fructose syrup (fructose is sweeter
than glucose so it can be used in
smaller amounts in slimming foods)