Biology Chapter 4

Question 1

enzymes are used in all…

Answer 1

Enzymes are used in all metabolic reactions that occur in cells. All chemical reactions
that occur in the cells are often termed as metabolic reactions.

Question 1

2 types of reactions

Answer 1

anabolic reactions and
catabolic reactions.

Question 2

Catalyst def

Answer 2

catalyst is a substance that can speed up chemical reatcion without itself being chemically changed at the end of the reaction

Question 3

anabolic reaction def

Answer 3

Anabolic reactions refer to the process of synthesizing complex molecules from simpler
molecules. Eg: synthesis of proteins from amino acids

BUILD UP

Question 4

cataboic reaction def

Answer 4

Catabolic reactions refer to the process of breaking of complex molecules into simpler
molecules. Eg: catalase breaks down hydrogen peroxide into oxygen and water

BREAK DOWN

Question 5

enzymes definition

Answer 5

enzymes are proteins. that function as biologicl caltalysts. they catalyse/speed up the rate of chemical reaction. they remain chemically unchanged at the end of the reaction.

Question 6

enzymes are made up of?

Answer 6

protein molecules folded to take on a 3d globular shapes.

Question 7

activation energy def.

Answer 7

the energy needed tpo start a chemical raction

Question 8

reactant? product?

Answer 8

R - the main thing eg a rock
P - Smaller pieces eg small pieces of a rock

Question 9

Enzymes linked with aftivation energy. how do they help?

Answer 9

enzymes provide an alternative pathway with lower activation energy needed to start a CR. enzymes catalyse chemical reactions. they speed up the rate of CR by lowering AE

Question 10

why are enzymes required to break large molecules into simpler and smaller substances?

Answer 10

• solube in water
• small enough to diffuse through cell membrane

Question 11

DIGESTIVE ENZYMES

Answer 11

amylase - starch into maltose
maltase - maltose into glucose
protease - proteins to polypeptides the. amino acid
lipase - fats to fatty acid to glycerol

Question 12

HOW ARE ENZYMES CLASSIFIED?

Answer 12

carbohydrases - digestst carbohydrates
proteases - digest proteins
lipases - digestts lipds/fats

Question 13

Enzyme specificty

Answer 13

each CR in a cell is catalysed by a unique enzyme

Question 14

Substrates def

Answer 14

the substance on which enzymes act.

Question 14

Why is an ezyme specific in its actions?

Answer 14

because of its 3d shape. the lock and key hypothysis explains how the shape of an enzyme affects its funtion

Question 15

What does enzyme reactions depedn on?

Answer 15

the active site.

Question 16

Lock: ?
Key: ?

Answer 16

enzyme
substrate

Question 17

What is an active site?

Answer 17

grooves on the surface of an enzyme molecule into whicg the substrate molecules with the matching shape fot.

Question 18

what happened when the substrate binds to the active site?

Answer 18

an enzyme-substrate complex is formed.

Question 19

what is enzyme-substrate complex

What happens after bidning?

Answer 19

a temporary molecule formed when substrate binds to the enzyme. reatcions occcur at active site to convert substrate molecules into product molecules. the product molecule then separates from enzyme.

Question 20

what happenes to enzyme molecule after product moelcuels separates from it?

Answer 20

enzyme molecules remain unchange. free to combine again.

Question 21

what are the 5 characteristics of enzymes?

Answer 21

1. speed up chemical reactions
2. specific in action
3. affected by temp
4. required in minute amounts and remain unchanged at the end of a reaction
5. affected by pH

Question 22

what are the 5 things of how enzymes are affected by temp?

Answer 22

1. less active at low temp
2. temp increases, rate pf enzyme reaction increases
3. optimum temp where enzyme is most ative
4. increasing temp above optimum causes decrease in the rate of enzyme reaction
5. enzymes have becme denatured

Question 23

enzymes are less active at low temp

Answer 23

at low temp:
- KE of molecule is low
- enzyme and substrate molecules move slowly
- rate of substrate molecules colliding with enzymes is low

Question 24

temp increases, rate pf enzyme reaction increases

Answer 24

• increaese in KE
• rate of effective collision has increased
• increase in rate of ESC formation

Question 24

optimum temp for enzymes

Answer 24

in humans, its about 40-45. optimum temp where enzyme is most ative

Question 25

Effect of Substrate Concentration REGION Y

At high concentration of the substrate…
All the active sites…
When this occurs there are more…

Answer 25

At high concentration of the substrate, the rate of enzyme reaction plateaus (at maximum).

● All the active sites available are occupied and engaged in the reaction. The enzymes are saturated.

● When this occurs, there are more substrate molecules present than enzyme molecules. Enzyme concentration is the limiting factor.

Question 25

What is a limiting factor??

Answer 25

A limiting factor directly affects the rate of a chemical reaction.

Question 26

Effect of Substrate Concentration REGION X
At a low concentration of the substrate, the enzyme..
At a low concentration of the substrate available…
As substrate concentration increases…
More ESC

Answer 26

At a low concentration of the substrate, the enzyme occurs in excess.

● At a low concentration of the substrate available, all substrate molecules can bind to the active site of enzymes immediately.

● As substrate concentration increases, the frequency of effective collisions between the active site of enzymes and substrates increases.

• More enzyme-substrate complexes are formed resulting in more products formed per unit time, hence the rate of enzyme reaction increases.

Question 27

Effect of enzyme concentration REGION X

At a low enzyme concentration…
This is because…
The frequency of…
More ESC…

Answer 27

At low enzyme concentrations, the rate of reaction increases as enzyme concentration increases.

● This is because more active sites are available to bind with the substrate molecules.

• The frequency of effective collisions between the active site of enzymes and substrates increases.

● More enzyme-substrate complexes are formed resulting in more products formed per unit time.

Question 28

Effect of enzyme concentration REGION Y
- As enzyme concentration increases…
- This is because
- All of the substrate molecules
- Substrate concentration

Answer 28

• As enzyme concentration increases to higher concentrations, rate of reaction plateaus and remains constant.

● This is because the number of substrate molecules is fixed and there is now an excess of enzyme molecules present.

• All of the substrate molecules are bound to an enzyme’s active site and are engaged in the reaction.

● Substrate concentration is the limiting factor.

Question 29

Enzymes are affected by pH. Example of enzymes that work best in alkali and acid

Answer 29

Proteases
Intestinal Enzyme

Question 29

DEFINE DENATURATION

Answer 29

the change in the 3d structure of an enzyme or any ither soluble protein, caused by heat or chemicals such as acids or alkalis.

Question 29

Increasing the temp above the optimum causes a rapid decrease in the rate of enzymes reaction

Answer 29

The active site of the enzyme molecule begins to lose its og shape and is no longer complementary to the substrate shape

Question 29

enzyme molecules when temp is too high?

enzyme molecules when temp is too low??

Answer 29

denatured

inactive

Question 30

what happens when enzymes are placed in pH conditions that vary from the optimum?

Answer 30

START TO DENATURE BRO NOT THAT DEEP

Question 31

optimum pH of the followinh:
protease in stomache

amylase

protease in samll intestine

Answer 31

1

6

a little shy of 8