Enzymes and Digestion Flashcards
Enzyme
a biological catalyst.
Catalyst
it is a substance which increases the speed of a reaction, without being changed or used up in a reaction.
How does an enzyme work?
.Every enzyme has an active site with a unique shape that fits onto the substance involved in the reaction.
.For the enzyme to work, the substrate has to fit into the active site of the enzyme.
. The chemical reaction then takes place.
. The products are then released
Optimum conditions for enzymes: Temperature
.A higher temperature increases the rate at first.
.But if it gets too hot, some of the bonds holding the enzyme together break.
.This changes the shape of the active site, so the substrate won’t fit anymore.
.The enzyme is said to be denatured
What is the optimum temperature in a human body?
37 degrees Celsius
Optimum conditions for enzymes:
pH
.If the pH is too high or too low, it interferes with the bonds holding enzyme together.
.This changes the shape of the active site, so the substrate can no longer fit.
. The enzyme is now denatured
What is the optimum pH in many enzymes?
pH 7, but not for all enzymes
REQUIRED PRACTICAL:
Investigating the effect of pH on amylase
- Put a drop of iodine solution into every well of a spotting tile
- Place a Bunsen burner on a heat-proof mat, and a tripod and gauze over it.
- Put a beaker on top of the tripod and heat the water until it is 35°C
- Use a syringe to add 1cm^3 of amylase solution and 1cm^3 of buffer solution with a pH of 5 to a boiling tube.
- Using test tube holders, put the boiling tube into he beaker of water and wait for 5 minutes.
6.Next, use a different syringe to dd 5cm^3 of a starch solution to the boiling tube - Immediately, mix the contents of the boiling tube and start a stop clock.
- Continuously sample to record how long it takes for the amylase to break down all the starch. Use a dropping pipette to take a fresh sample from the boiling tube every 30 seconds and put a drop into a well.
- Repeat the whole experiment with buffer solutions of different pH values.
- When the iodine solution remains browny-orange, starch s no longer present.
Control variables for pH practical
. Concentration of amylase solution
. Volume of amylase solution
Rate of reaction
Rate = 1000/time
Rate of reaction change over time
change/time
Mechanical digestion
teeth grinding down food and stomach churning up food
Chemical digestion
Where enzymes help to break down food
What do carbohydrases break down into?
convert starch into maltose
Amylase
Where it is produced:
salivary glands, pancreas and small intestine
Where it works:
mouth and small intestine