Enzymes And Biological Reactions

Question 1

Enzymes structure

Answer 1

Globular proteins, tertiary structure

Question 2

Structure bonds in enzymes

Answer 2

Hydrogen, Ionic, Disulphide

Question 3

Functions of enzymes

Answer 3

Biological catalysts- speed up rate of reaction. Reusable (unchanged). Specific

Question 4

Name the model where the substrate is complementary to the active site

Answer 4

Lock and key model

Question 5

Name the model where the substrate doesn’t fit the active site

Answer 5

Induced fit model. Enzymes slightly alters shape of active site putting strain on the bonds wearing and lowering the EA of the reaction

Question 6

What is activation energy? How do enzymes affect it?

Answer 6

Energy needed for a reaction to take place. Enzymes lower the AE- less energy needed to react.

Question 7

What is the turnover number?

Answer 7

The max. number of molecules of substrate that can be converted to product per unit time

Question 8

5 factors that affect enzyme activity

Answer 8

1) pH 2) temperature 3) substrate conc. 4) enzyme conc. 5) presence of inhibitors

Question 9

What is an anabolic reaction?

Answer 9

small+small=large molecule (condensation reactions- producing larger molecules)

Question 10

What is a Catabolic reaction?

Answer 10

Breaking down of larger molecules to smaller ones

Question 11

What are intracellular enzymes?

Answer 11

Inside the cell (e.g. breakdown of glucose to ATP)

Question 12

What are extracellular enzymes?

Answer 12

Released to work outside the cell (e.g. digestive enzymes)

Question 13

3 ways to measure enzyme activity

Answer 13

1) time taken for reaction. 2) rate of reaction (1/time). 3) concentration of products formed

Question 14

How do you plot a graph (axis)?

Answer 14

x axis= whatever you CHANGED. y axis= whatever you MEASURED

Question 15

How does temperature effect enzyme conc?

Answer 15

Increased temp= more KE= more successful collision= more ESC. Above optimum= denatured (bonds broken, shape altered)

Question 16

How does pH effect enzyme conc?

Answer 16

Optimum= charge of active site complimentary to charge of substrate. Small change= R groups repel= less ESC (can be reversed). Extreme change= denatured. pH buffers neutralise pH

Question 17

How does changing substrate conc. effect enzyme conc?

Answer 17

No. of ESC increases with substrate conc. More KE= more collisions. Levels off as active sites fill (enzyme conc= limiting)

Question 18

How does changing enzyme conc. effect enzyme conc?

Answer 18

Increased enzyme conc= increased RoR- excess of substrate so always collisions and ESC

Question 19

Source of industrial enzymes

Answer 19

Obtained from microorganisms e.g. fungi & bacteria. Grown in fermenters, reproduce rapidly, produce enzymes as part of usual metabolic activity

Question 20

What is an immobilized enzyme?

Answer 20

When an enzyme us fixed to an inert, insoluble matrix

Question 21

Four methods of immobilization

Answer 21

1) enzyme inclusion 2) cross linked enzyme 3) carrier bound enzyme 4) microcapsule

Question 22

Method: enzyme inclusion

Answer 22

entrapment in a cellulose mesh

Question 23

Method: cross linked enzyme

Answer 23

chemically bonded cross linked by glutaraldehyde

Question 24

Method: carrier bound enzyme

Answer 24

Adsorption onto inert material e.g. glass beads/ clay particles

Question 25

Method: microcapsule

Answer 25

encapsulation in alginate beads

Question 26

5 advantages of immobilized enzymes

Answer 26

1) reusable- lower costs. 2) not contaminated. 3) microenvironment means more stability at higher temps/ pH. 4) continuous. 5) several enzymes at once

Question 27

5 disadvantages of using immobilized enzymes

Answer 27

1) enzyme can detach and contaminate. 2) takes time to diffuse through gel. 3) gel can alter active site shape. 4) expensive and complex. 5) contamination is expensive

Question 28

How does a competitive inhibitor work?

Answer 28

similar shape to active site- blocks substrate. reversed by increasing substrate conc

Question 29

How does an non-competitive inhibitor work?

Answer 29

DO NOT COMPETE FOR ACTIVE SITE. attach to allosteric site and distort shape of active site

Question 30

How are biosensors used?

Answer 30

medical diagnosis. detect specific molecule in a mixture (immobilized enzymes) works as enzymes are specific