Transcript Enzymes for digesting proteins

Enzymes in Digestion
L.O: To understand how the enzymes
in the digestive system help digestion
Starter: digestion know the answer
Chew a piece of bread in your
mouth, do not swallow yet!
What do you notice about the taste? Can you
explain what is happening?
- Your teeth are physically breaking down the large
chunks
- Your saliva is mixing with the food making it
slippery and easier to swallow
- Enzymes in your saliva begin to break down the
carbohydrates into sugars
Digestive system
Now label your digestive system describing the jobs of the organs
Bile and The Liver
Bile is a chemical produced in the
liver and stored in the gall
bladder. It has 2 functions:
1) It neutralises stomach acid
and produces alkaline
conditions for enzymes to
work in
2) It emulsifies (“breaks down”
fats:
Fat
globules
Fat
droplets
How Enzymes Work
Enzymes have some important properties:
•They are proteins
•They are influenced by temperature and by pH
•They work best at certain temperatures and pH, eg 37 C
•They can be destroyed by extremes of heat and pH
•Each enzyme works on only one particular reaction
•Each enzyme molecule can affect a single reaction over and over again
•Most enzymes have names with ‘ase’ at the end, eg,
Carbohydrase acts on carbohydrates
Protease acts on proteins
Lipase acts on fats (lipids)
Record the chemical equations on the next few slides to show the action of the 3 enzyme groups.
Enzyme driven reaction
The digestion of carbohydrates can be represented
by the following equation.
Carbohydrates
carbohydrase
carbohydrase
Sugars
Enzymes for digesting proteins
Protein is made up of chains of amino
acids. There are over 20 different
kinds of amino acid.
The enzymes that digest proteins must amino
acids
be able to break the chemical bonds
between the different amino acids.
Enzymes that digest protein are known
as proteases.
The digestion of proteins can be represented by the
following equation.
protease
Protein
Amino Acids
sites of
enzyme
attack
Fat in our food
Fats are made up of a molecule of glycerol phosphate
attached to three fatty acid molecules. Fats are also
known as lipids.
The enzymes that digest fats must be able to break the
chemical bonds between the glycerol phosphates and the
fatty acids.
fatty
acids
site of
enzyme
attack
glycerol
phosphate
Fat digestion can be represented by the following equation:
lipase
Fat
Fatty Acids + Glycerol Phosphate
How Enzymes Work
Enzymes breaking down large carbohydrate molecules into smaller sugar
molecules that can pass across the gut wall
Blood Cell
Intestine Wall
Blood Vessel Wall
Enzymes
Carbohydrate
(eg starch)
Enzymes bind to
carbohydrate
Enzymes break the
links between the
sugars
Where are the enzymes made
and used?
• Digestive enzymes are different to other
enzymes because they work outside of your
cells.
• They are produced in glands, the pancreas,
and in the gut lining.
• Different enzymes work at different pH
levels so are found and used in different
parts of the digestive system (as we have
already found out the intestine is alkaline to
help break down fats).
Add this information onto your
diagram by colouring the
areas and doing a key
Slightly Alkaline
Acidic
Alkaline
Mouth
Carbohydrase (Amylase)
Starch  Simple sugars e.g. glucose
Stomach
Protease (Pepsin)
Protein  Amino Acids
Duodenum
Lipases / proteases (Trypsin) /
Carbohydrases
Fats  Fatty Acids and Glycerol
Protein  Amino Acids
Starch  Simple sugars e.g. glucose
The enzymes are made in the glands, pancreas and the gut lining
Enzymes in digestion
Carbohydrase (produced in the mouth,
pancreas and small intestine) breaks
_______ (a carbohydrate) down into
glucose:
Protease (produced in the stomach,
pancreas and small intestine) breaks
_______ down into amino acids:
Lipase (produced in the pancreas and
small intestine) breaks fats (_____)
down into fatty acids and glycerol:
Words – blood, lipids, proteins, digestion, starch, smaller
Bloodstream
Enzymes can be produced by the body to help _______. When they come
into contact and react with food they break it down into ______ pieces
which can then pass into the ______:
Digesting a Burger
Now describe what happens to a burger
during digestion including what parts are
digested where because of the enzymes
needed.
Multiple-choice quiz