m2 enzymes

describe properties of enzymes

• they have a tertiary structure

• they’re specific

• their structure is disrupted by high temperatures and extremes of PH

what are enzymes

• they control the rate of chemical reactions

• they are globular proteins

• they are biological catalysts, they are used in metabolic reactions , lower the activation energy and is not used up in the reaction

how do enzymes work , explain why activation energy is needed

• they work by lowering activation energy

• activation energy is energy needed to break existing bonds before new bonds can form

• chemical reactions can proceed quickly at low temps

define anabolic reactions

• they require energy

• usually combine simple molecules to form new molecules

define catabolic reactions

• release energy that is used to drive chemical reactions

• they break down larger molecules into more simple molecules

define intracellular reactions and gtive example

• reactions that occur within a cell

• (there are these reactions performed by catalase that works inside liver cells to break down hydrogen peroxide into oxygen)

define extracellular reactions and give examples

• reactions that occur outside of a cell

• (extracellular enzymes such as amylase that breaks down carbohydrates and tripsin that breaks down proteins)

where are extracellular/intracellular enzymes made

• both made inside a cell

• extracellular is released by exocytosis to be used outside of the cell such as protease or amylase

how do enzymes work

• enzymes combine reversibly with substrate molecules to form an enzyme-substrate complex

• the enzyme-substrate complex then breaks down to give the product and release the enzyme in an unchanged form

describe lock and key hypothesis

• thought that substrate has specific and complimentary shape to active site

• active site is a certain shape that doesn’t change shape at all

describe induced fit hypothesis

thought that the active site changes shape slightly to accommodate the substrate

describe the effect of temperature on rate of reaction

• as the temp increases the enzyme and substrate gain kinetic energy

• there are more successful collisions between the substrate and active site so there are more enzyme substrate complexes

• this occurs until optimum temperature

• after optimum temperature due to gaining a lot of kinetic energy the molecules in the enzyme move around more

• this breaks hydrogen and ionic bonds and denatures the enzyme

• the active site is no longer complimentary or specific in shape to the substrate

• the tertiary structure of the enzyme changes

• fewer enzyme substrate complexes are formed

describe the effect of PH

• by the H+ in the acid attract negative oxygen within hydrogen bond and negative ion within ionic bond since the H+ attracting the R  groups the hydrogen and ionic bonds will break

• this changes the tertiary structure of the enzyme

• the active site is no longer complimentary or specific in shape to the substrate

• there are fewer enzyme substrate complexes formed

• OH- in alkali will attract positive parts in the bond but still have same effect

describe the effect of substrate concentration

• as the substrate concentration increases there are more successful collisions between the active site and substrate

• there are more enzyme substrate complexes formed

• until all active sites are saturated it hits a plateu

• so the enzyme concentration becomes the limiting factor

describe the effect of enzyme concentration

• as the enzyme concentration increases there are more successful collisions between the active site and substrate

• there are more enzyme substrate complexes formed

• until all substrates are used up it hits a plateu

• so the substrate concentration becomes the limiting factor

describe coenzymes

• organic , not permanently bound to enzyme

• needed to activate enzyme

• produce specific shape of active site and take part in the reaction

• as concentration of coenzymes increase within a reaction rate of reaction increases

describe cofactors

• inorganic , permanently bound to enzyme

• produce specific shape of active site but do not take part in reaction

what are prosthetic groups

non protein group that is permanently bound to enzyme

give example of cofactor

• chlorine ion is a cofactor for amylase

give example of prosthetic group

• zinc 2+ is a prosthetic group for carbonic anhydrase

give example of coenzyme

• vitamins are a source of coenzymes

• if concentration of vitamins increases , rate of reactions will increase asw

function of competitive inhibitor

• substrate competes with inhibitor

• both substrate and inhibitor have complimentary specific shape to active site

• there will be fewer enzyme substrate complexes

• more substrate reduces chance of inhibitor getting into active site

function of non competitive inhibitor

• inhibitor fits into allosteric site away from active site

• this changes shape of active site

• substrate no longer complementary to active site

• there will be fewer enzyme substrate complexes

• active site change is non reversible so with this inhibtor the plateu will hit lower as fewer enzyme substrate complexes re

describe product inhibition

end product binds to enzyme away from active site preventing it from binding to any more substrate

describe inactive precursor

no biological activity until it’s metabolised by an enzyme into its active form