Enzymes

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  • Created by: ZoeKing98
  • Created on: 09-05-16 09:47
What is an enzyme?
A biological globular protein that catalyses out metabolic reactions
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What is an active site?
A specific structured area in a enzymes that 'fits' a complimentary substrate
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What is the complex of a bonded enzyme and substrate?
Enzyme-substrate complex
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What is a anabolic reaction?
A 'build up' reaction
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What is a catabolic reaction?
A 'break down' reaction
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Enzymes lower activation energy. True or false?
True - reactions can occur at lower temperatures in the presence of a catalyst
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What is free energy?
The energy of a system that is available to perform work
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What is essential about free energy for reactions?
That of the products must be lower than the substrates
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State two types of enzymes
-Intracellular: inside the cell..... -Extracellular: outside the cell
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What creates the specific enzyme structure?
The sequence of amino acids
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Explain the induced fit mechanism
The induced fit model is a step up from the lock-and-key model whereby a substrate fits exactly into the active site. The induced fit models insteads say the substrate is not quite the same shape, but the active site 'shifts' to fit.
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How could you measure enzyme catalysed reactions?
- formation of products (e.g. volume of oxygen produced from a reaction)... - the disappearance of the substrate
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How do you measure rate of change?
By the gradient of a curve/line through a tangent, dividing Y axis by X axis
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What effects enzyme action?
-temperature..... -pH...... -enzyme concentration..... -substrate concentration
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How does temperature effect enzyme action?
A rise in temp increase kinetic energy therefore causes molecules to move around more rapidly and collide more frequently, which are also more likely to be successful due to more reactions having the minimum activation energy as it is lower
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What is the optimum temperature of many enzyme reactions?
40 degrees Celcius. Typically after 60 degrees Celcius, rate drops since vibrations become so violent that bonds break and the shape of the active site changes by denaturation which is a permanent change. Temperatures are dependent on the enzyme.
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How does pH effect enzyme action?
- More hydrogen ions collide at the active site and alter the shape.... - Alter the charge of the amino acids so the shape changes
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What is the optimum pH for many enzymes?
7, but changes with the area of the enzymes. For example, pepsin in the stomach makes the enzymes there have an optimum pH of 2.
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How does enzyme concentration effect enzyme action?
As long as there is an excess of substrates, increasing the concentration of enzymes will increase as collisions are more frequent. But rate will level once there is no excess as all sites are bonding as rapidly as possible
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How does substrate concentration effect enzyme action?
If enzyme conc is fixed and substrate conc increased, the rate or reaaction increases as more substrates are available to form complexes. This increase only occurs while there is an excess of enzymes, levelling off when there is not
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Name the two types of enzyme inhibitors
Competitive and non-competitive
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How do competitive inhibitors inhibit reactions?
They have a shape similar to that of the complimentary substrate and are therefore able to bind at the active site and form a enzyme-inhibitor complex. This blocks substrates from 'entering' - the change can be reversible or irreversible
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How do non-competitive inhibitors inhibit reactions?
They do not have a similar shape to the complimentary substrate, instead binding at the allosteric site and alters the shape of the active site. This change can be reversible or irreversible.
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Which inhibitor decreases rate of reaction?
Competitive inhibitors as they compete with substrates to form a complex
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Non-competitive inhibitors decrease rate of reaction. True or false?
False - they have no effect since they do not have to compete for active sites with substrates
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Other cards in this set

Card 2

Front

What is an active site?

Back

A specific structured area in a enzymes that 'fits' a complimentary substrate

Card 3

Front

What is the complex of a bonded enzyme and substrate?

Back

Preview of the front of card 3

Card 4

Front

What is a anabolic reaction?

Back

Preview of the front of card 4

Card 5

Front

What is a catabolic reaction?

Back

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