4.2 Factors affecting enzyme activity

Question 1

How does temperature affect enzyme activity ?

Answer 1

increasing temp= increasing kinetic energy= particles move faster and collide more frequently
–> results in more frequent successful collisions between substrate and enzyme
–> increase in rate of reaction

Question 2

Low temperature? High temperature?

Answer 2

Too low= Low rate
–> Enzymes have too little kinetic energy and move slowly
–> Few successful collisions between enzyme and substrate

Too high= low rate
–> High heat breaks bonds maintaining tertiary structure of enzyme
–> active site becomes denatured and substrate no longer fits
–> No successful collisions= low rate ( abrupt decrease)

Question 3

Optimum temperature?

Answer 3

Optimum temperature is the temperature at which an enzyme has the highest rate of activity
–> lots of kinetic energy and move quickly
–> Higher frequency of successful collisions between enzyme and substrate = high rate

Question 4

Thermophilic vs psychrophilic

Answer 4

Thermophiles are organisms adapted to very hot living environments
–> enzymes are more stable due to increased number of bonds, esp hydrogen and sulfur bridges

Psychrophiles are organism adapted to very cold environments

Question 5

How does pH affect enzymes

Answer 5

Proteins and enzymes are affected due to the hydrogen and ionic bonds between amino acid R-groups in their 3D shape.
–> caused by interactions between polar and charged R groups of amino acids that form Primary structure)

–> change in pH= change in H+ conc.
More H+ = low pH acidic conditions
Less H+ = high pH alkaline conditions

Question 6

Low ph? High pH?

Answer 6

Acidity means less R groups interact and breaks bonds that maintain tertiary structure
–> change in active site= substrate no longer fits= no successful collisions= low rate

Alkalinity breaks bond maintaining tertiary structure of enzyme
–> change in active site= substrate no longer fits= no successful collisions= low rate

Question 7

Optimum pH?

Answer 7

High rate: when active site is the right shape at a certain H+ conc.
–> many collisions between working enzyme with specific shape and substrate
–> high rate

Question 8

Substrate/ enzyme concentration

Answer 8

High conc of either= higher colliison rate with active site of enzymes
–> formation of more enzyme-substrate complexes= higher rate

Question 9

What is Vmax

Answer 9

maximum rate of reaction possible for its concentration of substrate or enzyme
–> ALL OF ACTIVE SITES ARE OCCUPIED by substrate particles= no more ESC can be formed