2.1.4 Flashcards
What are enzymes?
Biological catalysts that speed up the metabolic reactions
What happened to the enzymes at the end of the reaction?
Nothing they remain unchanged so can be used again
How do you enzymes increase the reaction rate?
By lowering its activation energy
What are intracellular enzymes?
Enzymes act within cells
What type of enzyme is catalase and what does it do?
Intracellular
Quickly breaks down hydrogen peroxide into water and oxygen
What are extracellular enzymes?
Enzymes that act outside the cell that made them.
What form of nutrients in and how are they dealt with?
Polymer form: proteins/polysaccharides
They are broken down into smaller components first then absorbed through cell membrane
What is the role of extracellular enzymes?
They are released from cells to break down large nutrient molecules e.g. indigestion
Extracellular enzymes and single celled organisms, how do they work?
They release enzymes into immediate environment to break down polymers needed for nutrition
How do you enzymes work in multicellular organisms?
The large molecules need to be digested so that they can be absorbed into the bloodstream and transported around and used as substrate in cellular reactions
What enzymes are used for human digestion?
Amylase and trypsin
What is the structure of enzymes?
They are globular proteins
What is anabolic reactions?
Building up a molecule (synthesis)
What is catabolic reaction?
Breaking down a molecule Hydrolytic reaction (produces water and enzyme substrate complex)
What is metabolism?
Combination of anabolic and catabolic reactions
What metabolic pathway?
Sequence of enzyme controlled reactions
What is the mechanism of enzyme action?
Reactions happen when molecules occur in rights orientation
Speed increases, more collisions, more successful collisions, reaction rate will increase
What is specificity?
How one enzyme catalyse one biochemical reaction
What Is activation energy?
Energy needed to be supplied for most reactions to start
What do R groups in enzymes do?
Interact with substrate to make temporary bonds,
Putting strain on bonds within substrate therefore helping the reaction along
What is the induced fit hypothesis?
Initial interaction between enzyme and substrate is weak
These interactions rapidly induced changes in tertiary structure
Strengthening binding and putting strain on molecule
Therefore bonds in substrate weaken so the activation energy decreases
What affect does temperature have on the rate of reaction?
Temperature increases, increase in kinetic energy, faster movement, more collisions, more successful collisions
Faster rate of reaction
What happens when there is too much heat?
Bonds break, so the tertiary structure changes and so will the active site denaturing the enzyme
What effect does PH have on rates of reaction?
Low pH means acidity bricks bond is causing enzyme to be denatured
High PH means alkalinity breaks bonds causing denaturation
What affect the substrate concentration have on the rate of reaction?
Low means low rate as there is less chance of successful collisions
High means higher rate as there is more chance of successful collisions
What are cofactors?
Non-protein-helper-component
Transfer atoms or groups of atoms from one reaction to another in multistep pathway
What are co-enzymes?
Organic molecules derived from vitamins.
How do you coenzymes work?
Briefly find with or two active sites before or simultaneously with substrate.
What may happen to the enzyme because of a co-enzyme?
Maybe changed so can’t be reused (chemically changed)
Cofactors can be:
- Loosely or temporarily bound
- tightly bound and form a more permanent feature of enzyme
Describe what happens using carbonic anhydrase
It’s the enzyme needed for metabolism of CO2.
CO2 and H2O move into red blood cells and combine with carbonic acid.
Carbonic anhydrase catalyses this reaction.
What do you enzyme inhibitors do?
Inactivate enzymes by:-preventing them from catalysing
-slowing them down
What is competitive inhibition?
Molecule or part of molecule that fits into the active site.
Blocks the substrate
So it competes with the substrate to bind to active site.
What impact do you competitive inhibitors have on enzymes?
Reduce the rate of reaction but doesn’t change V-max
As an inhibitor what does aspirin do?
It inhibits COX enzymes, preventing chemicals responsible for producing pain fever being synthesised
What is non-competitive inhibition?
Molecule or part of molecule binds to allosteric site.
Causes enzymes tertiary structure to change and so the active site changes.
What is the allosteric site?
Location other than the active site
What affect does non-competitive inhibition have on the rate of reaction?
Reduces the rate of reaction as more active sites becomes unavailable
What are irreversible inhibitors?
Inhibitors that cant be removed (often toxic)
What is end product inhibition?
When product of reaction acts as an inhibitor to the enzyme that produces it.
What type of inhibition is end product inhibition?
Non compétitive réversible inhibition
Describe the two steps of respiration making ATP
-Addition of two phosphate groups to glucose molecule
-addition of second phosphate group results in initial breakdown of glucose.
The breakdown of glucose is catalysed by phosphofructokinase (inhibited by atp)
