B2 Enzymes (page 25) Flashcards
Finish the sentence;
Chemical reactions are what make you work, and enzymes are………
what make them work.
What are Enzymes?
they are catalysts produced by Living Things.
Living things have what going on inside them all the time?
they have thousands of different chemical reactions going on inside them all the time.
Why do chemical reactions inside living things need to be carfully controlled?
to get the right amounts of substances.
How can you usually make a reaction happen more quickly?
by raising the temperature. This would speed up the useful reactions but also the unwanted ones too…(not good).
Is there a limit to how far you can rise the temperature inside a living creature and why?
yes there is a limit to how far you can raise the temperature inside a living creature as the cells start getting damaged.
Living things produce enzymes that act as biological catalysts. explain what this is?
Ezymes reduce the need for high temperatures and we only have enzymes to speed up the useful chemical reactions in the body.
Explain what a Catalyst is?
it is a substance which INCREASES the speed of a reaction, without being CHANGED or USED UP in the reaction.
Enzymes are all large proteins, what do this mean?
all proteins are made up of chains of amino acids. These chains are folded into unique shapes, which enzymes need to do their jobs (see below).
Why do Enzymes have special shapes?
so they can catalyse Reactions.
Chemical reactions usually involve what?
things either being split aprt of joined together.
Every enzyme has an active site, explain what this is?
they have an active site, with a unique shape that fits onto the substance involved in a reaction.
Why are Enzymes really picky?
they usually only catalyse one specific reaction. This is because, for the enzyme to work, the substrate has to fit into its active site. If the substrate doesn’t match the enzyme’s active site, then the reaction won’t be catalysed.
(substrate means the surface on which an organism (e.g. plant, fungus or animal) lives or the substance on which an enzyme can act).
On page 25, 5), look at the diagram, it shows the ‘lock and key’ model of enzyme action. Explain how it works?
This is simpler than how enzymes actually work. In reality, the acive site changes shape a little as the substrate binds to it to get a tighter fit. This is called the ‘INDUCED FIT’ model of enzyme action.
What is the substance called that an enzyme acts on?
the substrate.
Do Enzymes need the right Temperature and pH?
Yes.
Changing the temperature changes the rate of what?
changes the rate of an enzyme-catalysed reaction.
Like with any reaction, a higher temperature increases the rate at first, but what happens if the enzyme gets too hot?
some of the bonds holding the enzyme toegether break.
What happens if the bonds holding the enzyme together break?
This changes the shape of the enzyme’s active site, so the substrate won’t fit any more. The enzyme is said to be denatured. (denatured basically means the key will no longer fit the lock)
All enzymes have an optimum temperature, what do this mean?
that they work best at.
(optimum means the most fabourable situation/temperture)
How do a pH affects enzymes?
if its too high or too low the pH interfered with the bonds holding the enzyme togeher. This changes the shape of the active site and denatures te enzyme.
(denature means the enzyme key will no longer fit the lock).
All enzymes have an optimum pH that they work best at, what is the optimum pH?
it’s often neutral pH 7, but not always - e.g. pepsin is an enzyme used to break down proteins in the stomach. It works best a pH 2, which means it’s well-suited to the acidic conditions there.
look at diagrams on pg 25 of the optimum temperture and optimum pH where the enzyme is most active.
Explain why enzymes have an optimum pH? (2 marks)
If the pH is too high or too low, it can interfere with the bonds holding the enzyme together. This changes the shape of the active site (1 mark) and denatures the enzyme (1 mark)
(make sure you use the special terms like ‘active site’ and ‘denatured’ - examiners will love it.
