Enzymes Flashcards
What is the function of an enzyme?
To control all the reactions in the cell
What can denature an enzyme?
Heat or pH levels
What is the active site?
The small area on its surface.
How do enzymes work?
The substrate enters the enzymes active site, and attaches to it. This lowers the energy needed for the reaction to start, allowing products to down more easily. The reaction takes place and products are formed.
What is an enzyme?
A biological catalyst: they speed up the reaction without being used themselves. Afterwards they are unchanged and free to catalyse more reactions.
How would you investigate the effect of temperature on enzyme activityby measuring how fast a substrate disappears?
Amylase breaks starch down into maltose. Measure the speed at which the starch disappears using iodine solution (turns from blue to browny/orange)
- Spots of iodine solution are placed on a sporting tile.
- 10 cm3 starch solution and amylase enzyme in a water bath at a constant temperature (10degrees)
- Immediately take a small sample and add it to the first drop of iodine solution on the tile.
- Time how long it takes for the starch to disappear by regularly sampling the starch solution, and use the times to compare rates between different tests
- Repeat the experiment at 20, 30, 40 and 50 degrees and compare the results
Control variables: volume and concentration of starch and amylase solution, volume of iodine solution
Where do enzymes catalyse reactions?
In the cytoplasm
How does the cell control the activities?
The nucleus contains the genes, which control the production of enzymes, which catalyse reactions in the cytoplasm.
Why are enzymes needed?
Body temperatures are low (about 37°C) and most of the reactions that happen in cells would be far too slow to allow life to go on without catalysts.
What is a substrate?
The molecule that an enzyme acts on.
Why is it called a ‘lock and key’ model?
The substrate fits into the active site rather like a key fitting into a lock.
What temperature do enzymes work best at?
Enzymes in the body have evolved to work best at 37°, this is the optimum temperature.
At what temperature roughly are enzymes in the body denatured?
40°C
What is the pH inside cells?
Around 7, neutral. Enzymes have adapted to work at this temperature.
Why are reactions faster at higher temperatures?
The molecules of enzyme and substrate have more kinetic energy so they collide more often. More collisions mean the reaction will take place more frequently.
