Enzymes

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  • Created by: Lotto65
  • Created on: 06-12-16 19:01
What do catalysts do?
Speed up chemical reactions
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Are catalysts normally changed themselves after a reaction?
No
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What sort of proteins are enzymes?
Globular proteins
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What is a substrate?
The reactant in an enzyme-catalysed reaction
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Where do enzyme-catalysed reactions take place?
In the active site of the enzyme
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What is the condition for catalysis?
The reactants are in a liquid
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Why is it necessary for reactants to be in a liquid?
Continual random motion so increased chance of collisions between substrate and active site
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What is necessary for binding to take place?
The shape and chemical properties of the active site complements the substrate
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What is a word to describe how enzymes have active sites specific to a certain substrate?
Substrate-specific
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What happens to the energy for a reaction when using an enzyme?
It is reduced for them to be converted into products
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Does catalysis happen very quickly?
Yes - many times per second
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How are enzymes normally found when used in industry?
Immobilised
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Name advantages of immobilisation of enzymes
Catalysis can be controlled by adding or removing enzymes; Concentrations can be higher; Reusable; More stable; Products not contaminated
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Name ways in which enzymes are immobilised
Adsorption, entrapment or aggregation, cross-linking
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What is adsorption?
Attaching enzymes to surfaces like glass, carbon, clay or resin
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What is entrapment?
Trapping the enzymes in a membrame or gel
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Give an example of what enzymes can be trapped in?
Alginate beads
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What is aggregation?
Bonding enzymes together into particles of up to 0.1mm diameter
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What enzyme can break up lactose?
Lactase
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What can lactose be broken up into?
Glucose and galactose
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What is the name of the process to break down lactose?
Hydrolysis
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For an immobilised enzyme to work, what must it be immobilised in/on?
Porous material so the substrate can get to the enzyme
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How is lactose made?
From microorganisms such as kluveromyces lactis
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Which solution makes alginate solution into alginate beads?
Calcium chloride solution (2%)
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What is the name of the clip that stops milk leaving the syringe barrel immediately?
Screw-gate clip
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Give four reasons why lactose-free milk is good
For those with a lactose intolerance; G+ G are sweeter so less sugar in sweet foods; Lactose crystallises in ice cream production but glucose and galactose more soluble so smoother texture; bacteria ferment G+G faster so production faster
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How much does enzyme activity increase roughly for every 10 degrees celcius rise?
Doubles
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Why does enzyme activity increase with temperature?
Gain kinetic energy so more collisions between substrate and active site more frequently due to faster molecular motion
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What is the most common optimum pH for enzymes?
pH 7
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Why does enzyme activity increase with increased substrate concentrations?
Random collisions between substrate and active site happen more frequently with higher substrate concentrations
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Why does high substrate concentration have little effect on enzyme activity?
Most of the active sites get occupied
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How many independent variables should you have in an experiment?
One
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Does it matter how large the range of independent variables is?
Should be large enough to show all trends e.g. pH 1-14
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Give examples of what to measure when doing an enzyme experiment
How long it takes for the substrate to be used up; The amount of product formed in a certain amount of time
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The results of an enzyme experiment should be qualitative/ quantitative...
Quantitative
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Why must an experiment be repeated?
To give replicate results and to find an average; To evaluate if they are reliable results
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What are control variables?
Other factors that affect enzyme activity
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Why must other variables be kept constant?
So they do not cause differences in results
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Other cards in this set

Card 2

Front

Are catalysts normally changed themselves after a reaction?

Back

No

Card 3

Front

What sort of proteins are enzymes?

Back

Preview of the front of card 3

Card 4

Front

What is a substrate?

Back

Preview of the front of card 4

Card 5

Front

Where do enzyme-catalysed reactions take place?

Back

Preview of the front of card 5
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Comments

BlackJack23

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proteins are globular and tertiary! it a key word and could give an extra mark

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