Ch.4 Enzymes and metabolism

Question 1

Metabolism is divided into _________ and ________.

Answer 1

catabolism (分解代謝); anabolism (合成代謝)

Question 2

Metabolism is the sum of the ________ reactions that takes place in an organism.

Answer 2

chemical

Question 3

Catabolism is the _______-_____ reactions in an organism.

Answer 3

breaking-down

Question 4

Anabolism is the _______-___ reactions in an organism.

Answer 4

building-up

Question 5

Energy is released in { catabolism / anabolism }.

Answer 5

catabolism

Question 6

Enzymes are biological c_______.

Answer 6

catalysts (催化劑)

Question 7

Enzymes speed up chemical reactions in organisms by lowering the _________ energy of the reactions.

Answer 7

activation

Question 7

Enzymes speed up chemical reactions in organisms by lowering the _________ energy of the reactions.

Answer 7

activation (活化)

Question 8

T/F: Each substrate has an active site.

Answer 8

F.

Each enzyme has an active site.

Question 9

Substrate(s) binds to the active site of enzyme to form an ______-________ complex.

Answer 9

enzyme-substrate

Question 10

T/F: Formation of enzyme-substrate complex greatly highers the activation energy of the reaction.

Answer 10

F

The formation of enzyme-substrate complex greatly lowers the activation energy of the reaction.

Question 11

After binding with enzyme molecule, the substrate(s) is converted into _______(s), which then dissociate from the active site.

Answer 11

product(s) (生成物)

Question 12

T/F: Enzyme actions are specific.

Answer 12

T

Question 13

Each enzyme has a ______ active site, which has a specific ______. It only acts on substrates that can fit into its active site.

Answer 13

unique; shape

Question 14

The specificity of enzyme actions can be explained by the ____-___-___ hypothesis.

Answer 14

lock-and-key

Question 15

Enzymes are proteins. Their structures and hence their activity are easily affected by __________ and ___.

Answer 15

temperature; pH

Question 16

Are enzymes reusable? Why?

Answer 16

Yes. Enzymes is released in its original form after reactions.

Question 17

Enzymes are needed in relatively { large / small } amounts.

Answer 17

small

Question 18

Enzyme activity is low when temperature is low. Explain why.

Answer 18

The kinetic energy of enzyme and substrate molecules is low. The molecules move slowly and the chance of them to collide with each other is low.

Question 19

At low temperature, enzymes are inactive. The ______ energy of enzyme and substrate molecules is low.

Answer 19

kinetic

Question 20

As temperature rises, both enzyme and substrate molecules have more kinetic energy. They ______ with each other more frequently. This increases the chance of forming enzyme-substrate complexes.

Answer 20

collide

Question 21

At optimum temperature, enzyme activity reaches a { maximum / minimum }.

Answer 21

maximum

Question 22

Enzymes work best at their ________ temperature.

Answer 22

optimum

Question 23

At high temperatures, enzyme activity { increases / dereases }.

Answer 23

decreases

Question 24

High temperatures cause a change in shape of the active site of the enzyme molecule. The enzyme is ________d.

Answer 24

denatured (變性)

Question 25

The substrate can no longer fit into the active site of the denatured enzyme to form the enzyme-substrate complex. The enzyme loses its _______ ability permanently.

Answer 25

catalytic

Question 26

At optimum pH, enzyme activity reaches a { maximum / minimum }.

Answer 26

maximum

Question 27

Enzymes work best at their ________ pH.

Answer 27

optimum

Question 28

At unsuitable pH, enzyme activity { increases / dereases }.

Answer 28

decreases

Question 29

Unsuitable pH causes ___________ of the enzyme. The substrate can no longer fit into the active site of the enzyme. The enzyme loses its catalytic ability permanently.

Answer 29

denaturation

Question 30

_________s are substances that decrease the activity of enzymes.

Answer 30

Inhibitors (催化劑)

Question 31

Give examples of inhibitors.

Answer 31

Cyanide(氰化物), heavy metals, etc.

Question 32

How are enzymes used in producing cheese?

Answer 32

Proteases(蛋白酶) coagulate milk.

Question 33

How are enzymes used to produce fruit juice?

Answer 33

Pectinase(果膠酶) breaks down the pectin(果膠) in plant cell wall to increase the juice production. It also breaks down the pectin in the juice to make the juice looks clear.

Question 34

How are enzymes used to produce liquid-centred chocolate?

Answer 34

Invertase(轉化酶) breaks down the sugars into more soluble forms.

Question 35

How are enzymes used to produce biofuel (e.g. bioethanol)?

Answer 35

Cellulase(纖維素酶) breaks down the cellulose in crops into sugars to increase the biofuel production.

Question 36

How are enzymes used to produce biodegradable(可生物降解的) plastic?

Answer 36

An enzyme extracted from a bacterium breaks down the plastic to shorten the time for a plastic bag to degrade.

Question 37

How are enzymes used to produce meat tenderizers(鬆肉粉)?

Answer 37

Papain (木瓜酶) breaks down the proteins in meat to soften the meat.

Question 38

How are enzymes used to produce biological washing powders?

Answer 38

Proteases and lipase(脂肪酶) break down the insoluble proteins and lipids in stains into soluble products.

Question 39

How are enzymes used to produce cleansers(洗面乳)?

Answer 39

Papain breaks down dead cells in the skin.

Question 40

How are enzymes used to produce stonewashed jeans(石磨藍牛仔褲)?

Answer 40

Cellulase breaks down the cellulose fibres of the jeans.

Question 41

How are enzymes used to produce drugs?

Answer 41

Lysozyme(溶菌酶) breaks down the cell wall of certain bacteria to kill them.

Question 42

Enzyme can speed up __________ reactions. This shortens production time and allows the mass production of products.

Answer 42

chemical

Question 43

Many enzymes work at __________ conditions. This does not require extreme conditions, such as very high temteratures and pressures.

Answer 43

moderate (中性的)

Question 44

Enzymes are _______ in action. This produces fewer unwanted products.

Answer 44

specific

Question 45

Enzymes are ________ and are needed in small amounts only. This lowers the cost of production.

Answer 45

reusable

Question 46

Enzymes are ________ to temperature and pH changes. They cannot be used if the production process involves a high temperature or an unsuitable pH.

Answer 46

sensitive

Question 47

Enzymes are easily affected by _______s → all containers used in the production processes have to be clean to prevent the containers from being contaminated with them.

Answer 47

inhibitors