2.1.4 enzymes
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are enzymes globular or fibrous proteins?
globular
how are enzymes biological catalysts?
speed up cellular reactions without being used up in said reactions
enzymes are specific in the shape of their _________ as each enzyme will only catalyse one reaction
active site
what does the binding of the complementary substrate to its specific enzyme form?
an enzyme-substrate-complex
describe induced fit model of enzyme activity
• more dynamic interaction • as an enzyme & substrate come together, their interaction causes a small shift in the enzymes structure in order to bind & form ESC to catalyse a reaction • conformational change
describe lock and key model of enzyme activity
• proposes that they enzyme & substrate fit together perfectly aka a complementary fit
why are products released from the active site?
they are no longer complementary in shape so the enzyme is recycled to catalyse the same reaction with another substrate molecule
what does it mean if an enzyme reaction is anabolic?
2 or more substrates are combined form a product e.g. they build up molecules
what does it mean if an enzyme reaction is catabolic?
substrate is broken down to form 2 or more products
why do energy changes occur when chemical reactions occur?
• changes in the structure of the substance • breaking (hydrolysis) & reforming (condensation) chemical bonds
is heat released or absorbed in endothermic reactions?
absorbed
is heat released or absorbed in exothermic reactions?
released
are most spontaneous reactions endothermic or exothermic?
exothermic
in living organisms energy released can be in 3 different energy forms:
• heat (thermal) • light • chemical
which 2 types of energy are often lost when released during reactions in living organisms?
heat and light
what do exergonic reactions involve?
release of energy during the reaction
what do endergonic reactions require?
input of energy
an example of an exergonic reaction
respiration
an example of an endergonic reaction?
synthesis of macromolecules e.g. proteins & photosynthesis
what is activation energy?
energy required for a reaction to begin
enzymes ______ the activation energy required for the reaction to proceed, so the reaction can proceed ______ & at ______ temperatures
1.lower 2. faster 3. lower
enzymes provide an ____________ pathway for the reaction to occur
alternative/different
how do enzymes lower the activation energy?
• provide an active site to bring the substrate closer together • moulding of the active site around the substrate helps to break bonds by putting strain on them
what does metabolism refer to?
all the chemical reactions which occur in organisms