Enzymes

HideShow resource information
Define active site
Specific to the substrate (complementary). The substrate binds to the active site and a chemical reaction occurs
1 of 34
Define enzyme action
Reduces activation energy
2 of 34
Define intracellular enzymes
Enzymes that are produced within the cell and used within the same cell (e.g. lysosomes)
3 of 34
Define extracellular enzymes
Enzymes produced within a cell but used outside of the cell
4 of 34
Define metabolism
Enzyme driven metabolic pathway
5 of 34
Complete this 'equation': enzyme+substrate->...
enzyme-substrate complex-> enzyme-product complex-> enzyme+product
6 of 34
Define activation energy
The amount of energy that needs to be supplied to the chemicals in a chemical reaction before the reaction will start
7 of 34
How do enzymes speed up the rate of reaction?
They lower the activation energy needed which allows reactions to occur at lower temperatures
8 of 34
How do enzymes help metabolic reactions to occur in the human body?
The human body temp of 37oC is relatively low so enzymes allow reactions to happen rapidly at this low temp
9 of 34
What happens to the shape of an enzyme when it denatures?
It changes shape which means the substrate can't fit into the active site any more so the reaction slows down/stops
10 of 34
What can cause an enzyme to denature?
a change in pH or temperature
11 of 34
What is the name of an earlier model of enzyme action?
Lock and Key Model
12 of 34
What does the Lock and Key model state?
The substrate fits into the enzyme in the same way a key fits in a lock. Not flexible/ the substrate fits the enzyme exactly
13 of 34
What is the Induced fit model?
States that the enzyme is flexible and can mould itself around the substrate. The enzyme-substrate complex can change shape slightly if the substrate doesn't exactly fit
14 of 34
How does the induced fit model explain why enzymes lower the activation energy needed to break bonds?
As the it changes shape, the enzyme puts a strain on the substrate molecule which distorts the bonds in the substrate ans subsequently lowers the activation energy needed
15 of 34
How do you work out the rate of reaction from a graph?
Draw a tangent to the curve of the graph using the normal line. Find the gradient by (dy/dx)
16 of 34
What is the optimum temperature?
The temp that results in the highest rate of reaction when using that enzyme
17 of 34
Why does increasing the temperature increase the rate of reaction?
The kinetic energy increases which causes molecules to move faster so substrates are more likely to collide with active sites. The collisions are also more likely to be successful
18 of 34
What happens to the enzyme when the temp is increased beyond the optimum?
The enzyme will start to denature which will decrease the rate of reaction as the active site changes shape so substrates can't fit in
19 of 34
Is denaturing by temperature permanent?
Mostly
20 of 34
What does the graph for rate of reaction when pH is involved look like?
A symmetrical bell
21 of 34
How do H+ and OH- ions affect enzymes? (when above and below optimum pHs)
They can disrupt the ionic and hydrogen bonds that hold the enzyme's tertiary structure. This causes the enzyme to denature as this changes the shape of the active site
22 of 34
What effect does increasing the substrate concentration have on the rate of reaction?
Increasing the concentration=increases rate of reaction bc there are more substrates available to bind with the active sites
23 of 34
What is the 'saturation point'?
all active sites are occupied so adding more substrate will not have an effect
24 of 34
What is the maximum rate of reaction called?
V(max)
25 of 34
What effect does increasing the enzyme concentration have on the rate of reaction?
More enzymes= collisions more likely so more enzyme-substrate complexes formed
26 of 34
What can limit the increased rate of reaction due to higher enzyme conc.?
If the amount of substrate is limited, there is a point where there are enough enzymes to deal with the substrate present so adding more enzymes will not increase the rate of reaction
27 of 34
How do competitive inhibitors work?
They compete with substrates to bind to active sites. They are a similar shape to the substrate so when bound to the active site, the inhibitor blocks the site so the reaction slows down
28 of 34
How can the effect of competitive inhibitors be reduced?
Increasing the substrate concentration will increase competition as it increases the chance of a substrate binding successfully with an active site
29 of 34
Are competitive inhibitors reversible?
Yes. They are bound to the active site by weak bonds so if the inhibitor leaves an active site a substrate can bind as normal
30 of 34
What site does a non-competitive inhibitor bind to?
Allosteric site
31 of 34
What do non-competitive inhibitors do to an enzyme?
They alter the shape of the enzyme which distorts the active site so substrates can't bind to it
32 of 34
Why won't increasing the substrate concentration have an effect on non-competitive inhibition?
These inhibitors are not competing with substrates so there will be no effect
33 of 34
Are non-competitive inhibitors permanent?
Mostly. Some can dissociate and the active site will revert to its original shape
34 of 34

Other cards in this set

Card 2

Front

Reduces activation energy

Back

Define enzyme action

Card 3

Front

Enzymes that are produced within the cell and used within the same cell (e.g. lysosomes)

Back

Preview of the back of card 3

Card 4

Front

Enzymes produced within a cell but used outside of the cell

Back

Preview of the back of card 4

Card 5

Front

Enzyme driven metabolic pathway

Back

Preview of the back of card 5
View more cards

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Biological molecules resources »