2.1.4 Enzymes COMPLETE

Question 1

Active Site

Answer 1

The intended area on the enzyme surface which has a complimentary shape to the substrate

Question 2

Catalyst

Answer 2

A Chemical that speeds up rate of reaction but remains unchanged

Question 3

Metabolism

Answer 3

Chemical reactions that take place in the living organisms

Question 4

Substrate

Answer 4

The molecule that is altered by an enzyme catalysed reaction

Question 5

DEFINITION- Enzyme

Answer 5

A globular protein with a specific shape that can act as a biological catalyst, speeding up metabolic reactions in living organisms

Question 6

Turnover Number

Answer 6

The number of reactions that an enzyme molecule can catalyse per second

Question 7

Intracellular Vs Extracellular

Answer 7

Intracellular work inside the cell catalysing reactions such as photosynthesis.
Example: Catalase
Extracellular work outside cells catalysing hydrolysis reactions that breakdown macromolecules
Example: Amylase & Trypsin

Question 8

How enzymes work

Answer 8

They speed up metabolic reactions by acting like a catalyst. Make substrates into products when they randomly collide

Question 9

Catabolic Reactions

Answer 9

Where substrates are broken down, strain is applied after the enzyme attaches so the molecule breaks apart.

Question 10

Anabolic Reactions

Answer 10

Where substrates are joined to make a larger product, When the enzyme attaches repulsion is reduced so they bond more easily

Question 11

Why enzymes are specific

Answer 11

The active site is specific for a reaction and the shape is maintained by the tertiary structure, therefore the enzyme only works with one molecule.

Question 12

Activation Energy

Answer 12

The energy that is required to begin a chemical reaction

Enzymes decrease the Ea so reactions take place more easily

Question 13

Lock and Key

Answer 13

The complimentary active site and substrate fit together like a lock and key

Question 14

Induced Fit

Answer 14

The enzymes active site changes slightly upon collision making the active site fit closer to the substrate.
May also be changes to the amino acids in the active site that contributes to holding the substrate in place.

Question 15

Temperature on rate of reaction

Answer 15

When heated kinetic energy increases so random collisions are more frequent, these also occur with more energy and greater force.
Therefore ROR increases

Question 16

Optimum Temperature

Answer 16

The temperature that gives the enzymes the maximum rate of reaction. Its a balance between increasing kinetic energy of the molecules and not denaturing it

Question 17

Temperature and Denaturation

Answer 17

When the tertiary structure I changed to the point where it no longer works, irreversible.
Molecules vibrate putting strain on the bonds, when the hydrogen and ionic bonds break the tertiary structure changes and ROR decreases

Question 18

ROR calculation

Answer 18

=1/ Time taken to reach end point

Refers to temp increasing by 10 degrees

Question 19

pH on Enzyme Reactions

Answer 19

H+ ions attach to negative charges and alter the active site. This is because they attach to the R groups in the amino chains and interfere with bonding.

Question 20

Optimum pH

Answer 20

Where the concentration of H+ gives the tertiary structure the best complimentary shape
A very narrow range is expected as small changes make big differences

Question 21

pH and Denaturation

Answer 21

Minor changes in pH do not denature enzymes as disrupted bonds reform. Denaturation only occurs with extreme pH away from the optimum

Question 22

Affect of Substrate Conc.

Answer 22

More substrate increases the rate of successful collision
When it reaches max value all the active sites are full so no more affect
V Max is the maximum initial velocity of rate of the enzyme catalysed reaction

Question 23

Affect of Enzyme Conc.

Answer 23

Increased enzyme conc. increases the ROR until all the substrates are full.
If both increased ROR consistently increases

Question 24

Enzyme Synthesis

Answer 24

Depending on the cells needs, genes for synthesising particular enzymes can be switched on or off

Question 25

Enzyme Degradation

Answer 25

In cells the proteins are broke down into constituent amino acids to be used to make new ones.

Question 26

Initial Reaction rates

Answer 26

Reaction rate will be highest when the substrate and enzymes initially mix
As the reaction processes it slows
Use a tangent to calculate

Question 27

Limiting Factors

Answer 27

Causes it to plateau as no more reaction can take place

Question 28

Cofactors

Answer 28

Some enzymes only work is there’s a non protein substance bound to them.
Two types including inorganic and organic

Question 29

Inorganic Cofactors

Answer 29

Ions
Do not permanently bind, and are not used up as don’t take part in the reaction.
Will either change the charge distribution or shape of the complex which makes the binding easier

Question 30

Organic Cofactors

Answer 30

Non protein molecules containing O, C and H
Bind temporarily to the active site, they take part in the reaction and are changed in some way however will be recycled.
Often act as carriers

Question 31

Prosthetic Groups

Answer 31

Coenzymes that permanently bind covalently

Question 32

Enzyme Inhibitors

Answer 32

A substance or molecule that slows down the rate of enzyme controlled reactions.
They can affect one or many enzymes.

Question 33

Reversible and Non reversible inhibitors

Answer 33

Don’t permanently bind to the enzyme or permanently bind.
Depends on the strength of the bonds, If covalently bonded then they can’t easily be removed
If Hydrogen or ionic bonds the inhibitor can be removed

Question 34

Competitive Inhibition

Answer 34

Molecules with a similar shape to the substrate will bind to the active site with no reaction. They block the active site, level of inhibition depends on relative concentration.

Question 35

Non competitive Inhibition

Answer 35

They bind to the Allosteric site and cause change to the tertiary structure so the active site changes and the substrate can no longer fit. Increasing conc. of substrate won’t make a difference.

Question 36

Metabolic Poisons

Answer 36

Interfere with metabolic reactions causing damage, illness or death.
E.g. Cyanide

Question 37

Venom

Answer 37

A mixture of toxins and different enzymes including ATPases, Phosphodiesterase’s and acetylcholinesterase inhibitors

Question 38

Control of metabolic Sequences

Answer 38

Many metabolic processes require a series of enzyme controlled reactions, these are called metabolic pathways.

Question 39

End product Inhibition

Answer 39

The end product binds to an earlier enzyme to change its active site reducing the ROR, this causes less product to be made. This is reversible and non competitive

Question 40

Enzyme Activation

Answer 40

Some enzymes are synthesised but are missing some amino acids. This means they are an inactive precursor. Many digestive enzymes are produced in this way. i.e. trypsin and pepsin