Proteins (enzymes) Flashcards
how are enzymes biological catalysts (3 marks)
- lower activation energy
- by providing alternate route
-speed up reaction
draw graph for w/ catalyst vs w/o (1 marks)
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describe induced fit model on enzyme action (4 marks)
- substrate binds to active site
-causing active site to change shape so its complementary to substrate - so enzyme-substrate complex forms
-causing bonds in substrate to bend, lowering activation energy
induced fit vs lock and key (2 marks)
-lock and key says active site ids fixed shape lock and substrate is key fits easily
-induced fit, active site changes shape to be complementary to substrate
what determines the function/ activity of a enzyme (2 marks)
- primary structure (sequence of amino acids) determines function
-tertiary structure determines shape of active site
explain specificity of enzymes (3 marks)
-tertiary structure determines shape of active shape
-active shape is complementary to substrate
-only this substrate can bind to active fit, induced fit and form E-S complex
explain how enzyme concentration affects the rate of reaction (6 marks)
talk about conc, limiting factor, collisions
-Increasing enzyme conc. → rate of reaction increases.
-Enzyme conc. = limiting factor (substrate in excess).
-More enzymes → more available active sites.
-More successful E-S collisions and E-S complexes.
-At a certain point, rate of reaction plateaus.
-Substrate conc. = limiting factor (all substrates in use).
explain how substrate concentration affects the rate of an enzyme-catalysed reaction (5 marks)
talk about limiting factor, collsiions, plateaus
-Increasing substrate conc. → rate of reaction increases.
-Substrate concentration = limiting factor (too few enzyme molecules to occupy all active sites).
-More successful E-S collisions and E-S complexes.
-At a certain point, rate of reaction plateaus.
-Enzyme conc. = limiting factor (all active sites saturated; excess substrate).
explain how temperature affects the rate of an enzyme-catalysed reaction (6 marks)
talk about optimum temp, collsisions, bonds
-Increasing temp. up to optimum → rate of reaction increases.
-Increase in kinetic energy.
-More successful E-S collisions and E-S complexes.
-Increasing temp. above optimum → rate of reaction falls.
-Enzymes denature; tertiary structure and active site change shape (hydrogen and ionic bonds break).
-Fewer E-S collisions and E-S complexes (substrate no longer binds to active site).
-Rate of reaction 0 when all enzymes denatured.
explain how pH affects the rate of an enzyme-catalysed reaction (5 marks)
talk about optimum ph, bonds, collisions
-pH above/below optimum pH → rate of reaction decreases.
-Enzymes denature; tertiary structure and active site change shape
-hydrogen and ionic bonds break
-Complementary substrate no longer binds/fits to active site.
-Fewer E-S collisions and E-S complexes.
explain how concentration of competitive inhibitors affects the rate of an enzyme-catalysed reaction (5 marks)
talk about induced fit,e-s complex, effect of increasing sub conc of inhibitor
- decrease rate of reaction
-Similar shape to substrate.
-Competes for / binds to / blocks active site so substrates can’t bind.
-Fewer E-S complexes.
-Increasing substrate conc. reduces effect of inhibitor (level of inhibition dependent on relative concs. of substrate and inhibitor).
explain how concentration of non-competitive inhibitors affects the rate of an enzyme-catalysed reaction. (6 marks)
talk about active site, e-s complex, effect of increasing sub conc on rate of reaction
-decrease rate of reaction.
-Binds to site other than the active site (allosteric site).
- changes Enzyme tertiary structure
-so substrate can’t bind to active site.
-Fewer E-S complexes.
-Increasing substrate concentration has no effect on rate of reaction as causes permanent change to active site.
draw graph for effect of enzyme conc on rate of enzyme controlled reaction
check google
draw graph for effect of substrate conc on rate of enzyme controlled reaction
check google
draw graph for effect of temperature on rate of enzyme controlled reaction
check google
draw graph for effect of pH on rate of enzyme controlled reaction
check google
draw graph for effect of competitive and non-competitive inhibitors on rate of enzyme controlled reaction
check google
