5: Enzymes

Question 1

Catalyst definition

Answer 1

substance that increases the rate of a chemical reaction and is not changed by the reaction

Question 2

Enzyme definition

Answer 2

proteins that function as biological catalysts

speed up the rate of metabolic reactions

Question 3

Why are enzymes important in all living organisms?

Answer 3

speed up the rate of metabolic reactions
without - would take too long to occur

(so we will probably die :D)

Question 4

Enzyme action

Answer 4

Lock and key hypothesis

1. Substrate that fits the specific active site of enzyme binds to create an ENZYME-SUBSTRATE COMPLEX
2. reaction occurs (catalysed by the enzyme)
3. products released

Question 5

Enzyme specificity

Answer 5

Each enzyme is complementary to only 1 type of substrate

has an active site - sequence of amino acids with specific shape that fit specific substrate

Question 6

Factors that affect the rate of an enzyme-controlled reaction (4)

Answer 6

• temperature
• pH
• substrate concentration
• enzyme concentration

Question 7

effect of temp on enzymes

above opt temp?

Answer 7

↑ temp = ↑ rate
until opt temp, particles have more KE - move faster = more successful collisions occur - more enzyme-substrate complexes formed

above optimum temperature:
enzymes DENATURE
active site distorted - heat breaks bonds that hold enzyme together
no longer fits the substrate- no enzyme-substrate complex can be formed (no reaction)

Question 8

effect of pH on enzymes

above opt pH?

Answer 8

opt pH = highest rate

pH is too ↑ or ↓ = rate ↓
enzymes DENATURE - active site distorted, no longer fits the substrate