Core Concepts; Enzymes and Biological Reactions
- Created by: Former Member
- Created on: 24-11-16 11:58
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- Enzymes & Biological Reactions
- Protein Nature
- reactions occur across metabolic pathways & include anabolic: build up; & catabolic: break down
- Enzymes are
- biological catalysts
- tertiary proteins with specific shape from bonding
- Sites of action
- extracellular: secreted from cells
- intracellular: in solution
- membrane bound
- Active Sites
- reactions occur in an enzyme-substrate complex
- Lock & Key
- enzymes have specifically shaped active sites that can only catalyse one reaction
- Induced Fit
- shape altered by substrate binding, but returns to normal
- Activation Energy
- minimum energy needed for molecules to react & break reactant bonds to form new ones
- More kinetic energy increases reaction rate as more successful collisions,
- temperature increase kinetic energy
- enzymes lower activation energy so reactions can occur at lower temps
- Factors Affecting Enzymes
- Temperature
- increase kinetic energy as more successful collisiond
- too high & vibrations break bonds so enzymes denatures
- pH
- small changes are reversible
- big changes cause denaturing
- Substrate conc
- big conc increases rate as more possible reactions
- at low conc, enzymes aren't working to full capacity
- rate plateaus when enzymes are saturated
- Enzyme conc
- enzymes are reusable so low conc needed to catalyse many reactions
- as increases, more collisions so faster rate of reaction
- Temperature
- Enzyme Inhibition
- Competitive
- shape similar to substrate so competes for active site
- makes collisions less likely but fixed by adding substrates
- Non-competitive
- bind at allosteric site & changes bonds & shape so substrate can't bind
- non-reversible
- Competitive
- Immobilsed Enzymes
- when enzyme is fixed on an inert matrix e.g. sodium alginate beads
- Benefits
- non-contaminating
- easy to recover and reuse
- easy to purify
- more stable as conditions change
- used to make lactose free milk
- fill beads with lactase which breaks lactose into glucose and galactose
- Protein Nature
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