Enzymes

Question 1

What are enzymes made up of?

Answer 1

Proteins

Question 2

What type of protein are enzymes?

Answer 2

Globular proteins

Question 3

State the roles of enzymes (3)

Answer 3

Reduce activation energy, speed up the reaction, break and bond molecules

Question 4

Differentiate between intracellular enzymes and extracellular enzymes

Answer 4

Intracellular: Used in the cells (E.g. ATPase , Helicase)
Extracellular: Those secreted out of the cell (E.g. pancreatic enzymes: -> Protease, Amylase, Maltase, Lipase,)

Question 5

Explain the lock and key theory

Answer 5

Enzymes have a specific cleft/shape that substrates must fit into to be catalyzed (complimentary shape).

Question 6

Which part of the (protein) enzyme binds with the substrate?

Answer 6

The R-group

Question 7

What complex is formed after the substrate-enzyme complex?

Answer 7

enzyme-product complex

Question 8

Explain the induced fit theory

Answer 8

Enzymes slightly change shapes to fit substrates into its active site

Question 9

Which 4 factors effect enzyme activity?

Answer 9

Temperature, pH, enzyme concentration, substrate concentration

Question 10

What is the optimum temperature for enzymes?

Answer 10

37 degrees celcius

Question 11

Explain what happens if the temperature gets too high/too low for the enzymes.

Answer 11

Too high: enzymes become denatured
Too low: enzymes become inactive

Question 12

Explain what happens if an enzyme is brought to a pH it is not made for.

Answer 12

Enzymes become inactive

Question 13

Explain the relation to enzymes and pH

Answer 13

Enzymes have an optimum pH and work efficiently only in a narrow range (of pH). If brought out of it, it becomes inactive.

Question 14

Which protein structures are enzymes? (primary - quartenary)

Answer 14

Tertiary structures (globular)

Question 15

Why does the enzyme concentration graph become saturated?

Answer 15

If all enzyme active sites are occupied by a substrate (assuming its the limiting factor), adding enzymes won’t increase the rate of reaction, and saturation will occur.

Question 16

Why does the substrate concentration graph become saturated?

Answer 16

Adding more substrates when all active sites of enzymes are occupied makes no difference, resulting in saturation as a further increase in rate of reaction is impossible.

Question 17

Why does increasing the number of substrate molecules increase the number of substrate-enzyme complexes?

Answer 17

An increase in substrates increases the probability of substrates colliding with enzymes, causing the enzyme-substrate complex.

Question 18

Define the Michaelis - Mentein constant (Km)

Answer 18

Concentration of substances that enables the enzyme to achieve half the maximum rate of reaction (Vmax/2)

OR.

is the substrate concentration at which an enzyme works at half of its maximum reaction rate (Vmax).

Question 19

Define Vmax

Answer 19

Maximum rate of reaction. The enzyme is saturated with substrates

Question 20

Explain affinity

Answer 20

The attraction/attachment between an enzyme and a substrate.
High affinity - strong attachment /attraction
Weak affinity - weak attachment/attraction

Question 21

What does a lower Km mean in terms of affinity?

Answer 21

stronger affinity

Question 22

What is the Michaelis-Mentein formula?

Answer 22

v0 = Vmax x [S] / Km + [S]

Question 23

In the Michaelis-Mentein formula, what does each variable represent?

Answer 23

v0 = Initial reaction rate
Vmax = Maximum reaction rate
Km = Half of Vmax
S = substrate concentration

Question 24

Define what an inhibitor is

Answer 24

An inhibitor is a molecule that slows down the rate of reaction of enzymes.

Question 25

State and explain the 4 types of inhibitors

Answer 25

//Competitive inhibitors: molecules that compete with the substrate for the active site of enzymes, inhibiting the reaction by preventing substrate binding.
//Non-competitive inhibitors: molecules that bind to a site other than the active site (such as the allosteric site), causing a change in the enzyme’s shape, which can render the enzyme inactive or slow down the reaction.
//Irreversible inhibitors: molecules that permanently bind to the enzyme, often leading to denaturation, and thus completely inhibit its activity. (e.g. Penicillin and Nervous gas)
//End product inhibitors: When a reaction needs to stop producing, the accumulation of end products inhibits earlier enzymes in the pathway by binding to them. This prevents further reactions and helps regulate the overall process.

Question 26

What are immobilizing enzymes?

Answer 26

Keeping enzymes in one place (immobilized) so they can’t move around. It helps them work better and allows for reuse in different reactions.
Typically for commercial purposes

Question 27

List 4 advantages of immobilizing enzymes.

Answer 27

1-Not contaminated
2-More tolerant to pH
3-More tolerent to temperature
4-Bead formation protects the vulnerable parts