cc4 - enzymes

lock and key model

the enzyme's active site is specifically shaped to fit a particular substrate - they are complimentary, similar to a key fitting into a lock

induced fit model

The active site and substrate are not complimentary so the substrate changes the shape of the active site as it enters to allow the substrate to fit, lowering the activation energy

catalyst

a substance that increases the rate of a chemical reaction without being consumed in the process.

denaturisation by heat

the hydrogen bonds break, changing the shape of the active site so it can no longer form enzyme substrate complexes

activation energy

the energy needed to break existing chemical bonds inside molecules

metabolism

all reactions happening in a cell/organism

anabolic reactions

metabolic processes that build larger molecules from smaller ones, requiring energy.

catabolic reactions

metabolic processes that break down larger molecules into smaller ones, releasing energy.

intracellular/extracellular

intra=refers to processes occurring inside a cell, extra=outside of a cell

what type of protein are enzymes?

globular proteins, mainly tertiary structure with spherical shape

effects on rate of reaction

• enzyme concentration

• substrate concentration

• temperature

• pH level

competitive inhibitors

bind to the active site of the enzyme because they are similar shapes, blocking it so the substrate is unable to bind, decreasing the number of enzyme-substrate complexes

non-competitive inhibitors

binds to the enzymes allosteric site which changes the shape of the active site because the bonds are disrupted, meaning the enzyme and substrate are no longer complementary so no enzyme-substrate complexes can from

what are immobilised enzymes + 2 types?
evaluate

enzymes that cant move, are attached to an inert support, alginate beads and cellulose fibres

+can be reused, more stable to changes in temp and pH, denature at a higher temp

-initial cost to immobilise enzyme, maximum rate is reduced because its harder to form enzyme-substrate complexes

Buffer solution

Molecule that maintains a constant pH by neutralising small volumes of acid or base

Catalysis

Increasing the rate of chemical reaction via the reducation in activation energy

Enzyme

Biological catalyst (a protein) used to speed up the rate of biochemical reactions without being used up

Lysozyme

An enzyme found in tears and saliva that destroys pathogenic bacteria by breaking down its cell walls. the cell walls are polysaccharides, lysosomes have a ridge (shown by X-ray diffractor) that fits 6 amino sugars held in place by hydrogen and ionic bonds and it breaks the glyosidic bonds in the chain art a specific site

catalase

an enzyme with a high turnover, turns toxic waste hydrogen peroxide into harmless oxygen and water

why does big pH changes effect enzyme-substrate complexes

charges in the active site and the substrate need to attract. Active sites charge is determined by the number of free H+ and OH- ions, if there is too many of one the active site will have the same charge as the substrate and the molecules will repel (denaturisation)

Competitive inhibitor graph shape

At lower substrate concentration, rate is reduced

At higher substrate concentrations, rate is same as without inhibitor

Non-competitive graph shape

Rate is reduced at all substrate concentrations, maximum rate is not achieved