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Enzymes Flashcards

1
Q

What is a catalyst?

A

A substance that speeds up the rate of a chemical reaction, without itself being altered at the end of the reaction.

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2
Q

What are enzymes?

A

Biological catalysts found in living things, made of protein.

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3
Q

How do enzymes affect chemical reactions?

A

They alter the rate of chemical reactions without being changed themselves at the end of the reactions.

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4
Q

What do enzymes do to activation energy?

A

They lower the activation energy of a chemical reaction.

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5
Q

What is activation energy?

A

The energy needed to start a chemical reaction.

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6
Q

What happens to reaction rates in the presence of an enzyme?

A

The rate at which the products are formed is increased.

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7
Q

Fill in the blank: Enzyme-catalysed reactions can be classified into two groups: _______ reactions and catabolic reactions.

A

Anabolic

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8
Q

What are anabolic reactions?

A

Reactions in which complex substances are synthesised from simpler ones.

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9
Q

What are catabolic reactions?

A

Reactions in which complex substances are broken down into simpler ones.

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10
Q

True or False: Enzymes are changed during the reactions they catalyze.

A

False

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11
Q

What is the role of special enzymes in the synthesis of proteins?

A

They build up proteins from amino acids

This process occurs in the cytoplasm.

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12
Q

During photosynthesis, enzymes synthesize glucose from which two substances?

A

Carbon dioxide and water

This process is crucial for producing energy in plants.

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13
Q

What do digestive enzymes do to large molecules in food?

A

They break them down into smaller, soluble molecules

These smaller molecules can pass through the cell membrane.

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14
Q

What is an example of a toxic molecule that certain enzymes break down?

A

Hydrogen peroxide

It is produced during some chemical reactions in cells.

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15
Q

What enzyme breaks down hydrogen peroxide, and what are the products?

A

Catalase; water and oxygen

Catalase is abundant in the blood and liver of mammals.

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16
Q

What is released when glucose is broken down during cell respiration?

A

Energy, carbon dioxide, and water

This process is essential for cellular energy production.

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17
Q

What type of digestive enzyme digests carbohydrates?

A

Carbohydrases

They are responsible for breaking down carbohydrate molecules.

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18
Q

Which enzyme digests starch to maltose?

A

Amylase

It is a type of carbohydrase.

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19
Q

What is the function of proteases?

A

Digest proteins

They break down proteins into smaller peptides and amino acids.

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20
Q

Which enzyme digests lactose to glucose and galactose?

A

Lactase

It helps in the digestion of dairy products.

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21
Q

What do lipases digest?

A

Fats (lipids)

They convert lipids into glycerol and fatty acids.

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22
Q

What is the role of pepsin in digestion?

A

It digests proteins to polypeptides

Pepsin is active in the stomach.

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23
Q

What do peptidases do?

A

Digest polypeptides into amino acids

They are essential for protein digestion.

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24
Q

Fill in the blank: Steapsin digests lipids to _______.

A

Glycerol and fatty acids

This enzyme is a type of lipase.

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25
What represents the activation energy of the reaction without an enzyme?
X + Y
26
What represents the activation energy of the reaction with an enzyme?
Y
27
What is the term used for the substances that enzymes work on?
Substrates
28
Where do substrates fit on an enzyme?
Active site
29
What hypothesis explains enzyme specificity?
Lock-and-key hypothesis
30
What is an enzyme-substrate complex?
The complex formed when a substrate binds to the active site of an enzyme
31
What characteristic of enzymes contributes to their specificity?
Three-dimensional shape
32
True or False: Each chemical reaction is catalyzed by a unique enzyme.
True
33
Fill in the blank: A substrate fits into an _______ on the surface of an enzyme.
active site
34
According to the lock-and-key hypothesis, which component is like a lock?
Enzyme
35
According to the lock-and-key hypothesis, which component is like a key?
Substrate
36
What is the term for the energy required to initiate a chemical reaction?
Activation energy
37
What occurs at the enzyme's active site?
Chemical reactions occur to convert the substrate into products.
38
What happens to the enzyme after the products leave the active site?
The enzyme remains unchanged and is free to catalyse another reaction.
39
What is the relationship between the amount of enzyme and substrate in a reaction?
Only a small amount of an enzyme is needed to catalyse reactions for a large amount of substrate.
40
True or False: The shape of the substrate is the same as the enzyme's active site.
False
41
What must the shape of the substrate be in relation to the enzyme's active site?
The shape of the substrate must be complementary to the enzyme's active site.
42
Fill in the blank: The _______ has protruded surfaces that match with depressed surfaces of the enzyme's active site.
[substrate]
43
What is formed when the substrate binds to the enzyme?
An enzyme-substrate complex.
44
What is released after the chemical reaction within the enzyme's active site is completed?
Products leave the active site.
45
What does the enzyme do after catalysing a reaction?
It can be used repeatedly.
46
What factors directly affect the rate of enzyme-catalysed reactions?
Temperature and pH ## Footnote Both temperature and pH can influence enzyme activity significantly.
47
At what conditions do enzymes work best?
At their optimum temperature and pH ## Footnote Each enzyme has specific conditions under which it operates most effectively.
48
How are enzymes characterized in relation to temperature?
Enzymes are temperature sensitive ## Footnote Changes in temperature can lead to changes in enzyme activity.
49
What happens to enzyme and substrate molecules at low temperatures?
They have low kinetic energy and move slowly ## Footnote This results in a lower chance of collision between enzyme and substrate.
50
How does increasing temperature affect enzyme reactions?
The rate of enzyme reactions increases ## Footnote Increased temperature leads to more kinetic energy and higher collision rates.
51
What is the effect on the rate of enzyme reaction for every 10°C increase in temperature?
The rate of enzyme reaction doubles ## Footnote This effect continues until the optimum temperature is reached.
52
What is the optimum temperature for enzymes in the human body?
37°C ## Footnote This temperature is crucial for optimal enzyme activity in human physiological conditions.
53
Fill in the blank: Enzymes are said to be _____ when they lose their functional shape due to extreme temperature.
denaturing ## Footnote Denaturation can lead to loss of enzyme activity.
54
What happens to the chances of substrate molecules colliding with enzymes as temperature increases?
The chances increase ## Footnote Higher kinetic energy leads to more frequent collisions.
55
What happens to the rate of enzyme reaction when the temperature is increased beyond the optimum temperature?
The rate of enzyme reaction rapidly decreases ## Footnote High temperatures irreversibly break the bonds that keep the enzyme in shape.
56
What is denaturation in the context of enzymes?
The change in the three-dimensional structure of an enzyme or any other soluble protein ## Footnote It may be caused by heat or chemicals such as acids and alkalis.
57
At what temperature are most enzymes irreversibly denatured?
Above 60°C
58
What occurs to the active site of an enzyme when it is denatured?
The active site loses its original shape and the substrate can no longer fit into it.
59
How does pH affect enzyme activity?
As pH deviates from the optimum pH, the rate of enzyme reaction rapidly decreases.
60
What can cause denaturation of enzymes?
Extreme changes in acidity or alkalinity of the solution.
61
Do different enzymes have the same optimum pH values?
No, different enzymes have different optimum pH values at which they work best.
62
True or False: Low temperatures cause an enzyme to become denatured.
False ## Footnote Low temperatures do not denature the enzyme but reduce enzyme activity.
63
What is the effect of low temperatures on enzyme activity?
Low temperatures reduce the rate of enzyme activity.
64
How does temperature affect the rate of enzymatic reaction?
It has an asymmetrical bell-shaped curve.
65
How does pH affect the rate of enzymatic reaction?
It has a symmetrical bell-shaped curve.

Biology (6 decks)

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