How Enzymes Are Affected

Question 1

Enzymes important

Answer 1

•allow chemical reactions to occur fast enough to support life
•speed up rate of reactions, by lowering activation energy
•anything an enzyme combines with is a substrate
•enzyme can catalyse 1-10,000 molecules per second
•not altered during their reactions
•highly specific for their substrate
•generally, one specific enzyme for each specific chemical reaction

Question 2

Why enzymes can be affected

Answer 2

•enzymes made of proteins, which are chains of amino acids, that fold & twist creating a unique shape
•shape of enzyme’s active site affected by this - can change ability to bind to substrate
•when active site changes shape, enzyme has denatured

Question 3

Factors affecting enzymes

Answer 3

•temperature - increase temp speeds up reaction, too hot though and denature
•pH - optimal pH range, change can slow reaction, extreme pH can denature
•enzyme concentration - increasing concentration speeds up reaction (if there is a substrate)
•substrate concentration - increases rate of reaction, but once all enzymes bound, further substrate increase will have no affect (enzymes will be saturated & working at max rate)

Question 4

Graphically - temperature

Answer 4

•as temp increases, rate of reaction increases
•max rate reached at optimum temp
•increase past optimum, rate of reaction decreases until denatured
•heat gives molecules more kinetic energy, causing more collisions & enzyme-substrate complexes
•too much kinetic energy causes active sit to change shape - enzyme denatures (stops working)

Question 5

Graphically - pH

Answer 5

•below optimum pH, rate of reaction low or 0
•maximum rate of reaction at the optimum pH
•above optimum, rate of reaction low or 0
•acidic conditions, H+ ions break hydrogen bonds & denature enzymes
•optimum pH - the pH enzymes react fastest at
•alkaline conditions (pH above 7), OH- ions break hydrogen bonds & denature enzymes

Question 6

Graphically - concentration of enzyme

Answer 6

•as enzyme concentration increases, rate of reaction increases
•as enzyme concentration increases further, rate of reactions plateaux (level off)
•reactions speed up because there are more enzyme molecules to form more enzyme-substrate complexes
•levels off because all substrate molecules available are being acted upon - substrate concentration becomes the limiting factor

Question 7

Graphically - concentration of substrate

Answer 7

•substrate concentration increases, rate of reaction increases
•substrate concentration increases further, rate of reactions plateaux
•speeds up reaction because there are more substrate molecules to form more enzyme-substrate complexes
•plateaux at saturation point - all active sites occupied by a substrate, enzyme concentration becomes limiting factor

Question 8

Normal body temperature

Answer 8

•normal body temp 37 degrees Celsius
•infection will cause rise in body temp, rise too high (above 41 degrees Celsius) enzymes start to denature
•if infection continues, enzyme dysfunction can be permanent
•same applies if body too cold (hypothermia)

Question 9

Enzymes in digestion

Answer 9

•digestive tract provides variety of pH ranges for enzymes to function
•digestive enzymes adapted to only work at specific pH of area where found, when it moves to new area they denature.
•oesophagus (pH 7), stomach (pH 1-2.5, 5 when fed)

Question 10

Reduction of enzymes

Answer 10

•enzymes found in saliva, pancreas, intestines, and stomach - break down food into nutrients body uses for growth & cell repair
•conditions that affect pancreas (cystic fibrosis, pancreatic cancer) can reduce number of enzymes produced
•this makes it difficult to digest food - get nutrition
•in liver, elevation in liver enzymes can be caused by liver diseases/medications (fatty liver disease & statins)