Unit 3D

Question 1

What is an enzyme?

Answer 1

An enzyme is a protein molecule that acts as a catalyst in a biochemical reaction.

Enzymes speed up chemical reactions without being consumed in the process.

Question 2

What are proteins made of?

Answer 2

Proteins are made of amino acids.

There are 20 different amino acids that combine in various sequences to form proteins.

Question 3

What is the central component of an amino acid?

Answer 3

A central (alpha) carbon with four chemical groups attached to it.

The four groups are a hydrogen atom, an amino group, a carboxyl group, and a variable R group.

Question 4

How are amino acids linked together?

Answer 4

Amino acids are linked together by peptide bonds.

These bonds are formed through condensation reactions.

Question 5

What occurs during a condensation reaction between two amino acids?

Answer 5

Water is produced.

This reaction results in the formation of a peptide bond between the amino acids.

Question 6

What is a dipeptide?

Answer 6

A dipeptide is formed by two amino acids linked by a peptide bond.

Question 7

What is a tripeptide?

Answer 7

A tripeptide is formed by three amino acids linked together.

Question 8

What is a polypeptide?

Answer 8

A polypeptide is formed when many amino acids join together.

A polypeptide with more than 50 amino acids is called a protein.

Question 9

What is the difference between the N terminal and C terminal of a protein chain?

Answer 9

The N terminal is the start of the protein chain, and the C terminal is the end of the protein chain.

Question 10

Fill in the blank: A polypeptide with more than 50 amino acids is called a _______.

Answer 10

protein.

Question 11

Research the structure of the R groups of which two amino acids?

Answer 11

Cysteine and threonine.

Question 12

What forms when two amino acids undergo a condensation reaction?

Answer 12

A dipeptide is formed.

Question 13

What is produced during the condensation reaction of amino acids?

Answer 13

Water is produced.

Question 14

True or False: There are 20 different R groups, leading to 20 different amino acids.

Answer 14

True.

Question 15

What is the active site of an enzyme?

Answer 15

The part of the enzyme where the biochemical reaction takes place

The active site consists of a specific shape formed by a small number of amino acids.

Question 16

What are the common shapes of secondary structures in proteins?

Answer 16

• a-helix
• B-pleated sheet

These structures are formed by orderly shapes of polypeptide chains.

Question 17

What holds the secondary structure of a protein in shape?

Answer 17

Hydrogen bonds

The bonds are between the -NH of one peptide link and the -C=O of another amino acid.

Question 18

How does the tertiary structure relate to an enzyme’s active site?

Answer 18

The tertiary structure gives the enzyme the shape of its active site

The specific shape allows for the binding of substrates.

Question 19

What happens when an enzyme catalyzes a reaction?

Answer 19

The substrate binds to the active site and is converted into products

After the reaction, the product is released, and the active site is available for further reactions.

Question 20

What is a substrate in the context of enzyme activity?

Answer 20

The substance that binds to the active site of an enzyme

Specific substrates have a complementary shape to the active site.

Question 21

What is the ‘lock and key’ mechanism?

Answer 21

The concept that the active site of an enzyme is a specific shape that only a complementary substrate can fit

This mechanism illustrates how enzymes are specific to their substrates.

Question 22

What happens to an enzyme if the temperature exceeds 40°C?

Answer 22

The enzyme denatures and loses its shape

This occurs because the hydrogen bonds break, altering the active site.

Question 23

What is a catalyst?

Answer 23

A substance that increases the rate of a reaction without being changed itself

Catalysts remain unchanged at the end of the reaction.

Question 24

What is required for a reaction to occur according to collision theory?

Answer 24

• Particles must collide
• Particles must have sufficient energy

The minimum energy required for a reaction to occur is known as the activation energy.

Question 25

What is meant by 'denatured' in terms of enzymes?

Answer 25

An enzyme that has lost its functional shape and can no longer act as a catalyst ## Footnote Denaturation can result from extreme temperatures or pH changes.

Question 26

Fill in the blank: The _______ binds to the active site of the enzyme.

Answer 26

substrate ## Footnote The specific substrate fits into the active site enabling the biochemical reaction.

Question 27

What are enzymes?

Answer 27

Biological catalysts that speed up reactions and remain unchanged at the end of the reaction. ## Footnote Enzymes participate in reactions but are not consumed.

Question 28

What is a catalyst?

Answer 28

A substance that speeds up a reaction. ## Footnote Catalysts can be involved in the reaction but are not permanently changed.

Question 29

What must occur for a reaction to take place according to collision theory?

Answer 29

Particles must collide and have enough energy to react. ## Footnote The energy of the collision depends on the speed and angle of the particles.

Question 30

What is activation energy?

Answer 30

The minimum energy needed for particles to react. ## Footnote Activation energy is a crucial factor in determining reaction rates.

Question 31

How does an enzyme affect activation energy?

Answer 31

It lowers the activation energy needed for a reaction. ## Footnote This increases the number of successful collisions and speeds up the reaction.

Question 32

What is catalytic activity?

Answer 32

The increase in the rate of a reaction caused by the inclusion of an enzyme. ## Footnote Catalytic activity is a key characteristic of enzymes.

Question 33

What is a substrate?

Answer 33

The molecule that is affected by the action of the enzyme. ## Footnote Substrates are converted into products in enzyme-catalyzed reactions.

Question 34

What is an active site?

Answer 34

The area of an enzyme where a substrate binds. ## Footnote The active site is specific to the substrate it binds.

Question 35

What does it mean if an enzyme is denatured?

Answer 35

The tertiary structure of the enzyme is changed. ## Footnote Denaturation can result from changes in temperature or pH.

Question 36

How can enzyme reactions be measured?

Answer 36

By measuring the decrease in substrate or the increase in product. ## Footnote Measuring product increase is often easier because the starting measurement is known.

Question 37

Why is it important to record the initial rate of an enzyme-catalyzed reaction?

Answer 37

Because the rate will decrease as the substrate is used up and its concentration decreases. ## Footnote Initial rates provide a baseline for understanding the reaction kinetics.

Question 38

Fill in the blank: The _______ is the area of an enzyme where a substrate binds.

Answer 38

active site

Question 39

True or False: Enzymes are consumed in the reactions they catalyze.

Answer 39

False

Question 40

What do enzymes need to work effectively?

Answer 40

Specific conditions ## Footnote If these conditions are not present, enzyme-catalysed reactions may slow down or not work at all.

Question 41

What is the optimum temperature for enzymes in humans?

Answer 41

About 40°C ## Footnote Each enzyme has an optimum temperature at which it works fastest.

Question 42

How does the reaction rate change as temperature increases up to the optimum temperature?

Answer 42

Rate increases ## Footnote As temperature increases, the reaction rate increases until the optimum temperature is reached.

Question 43

What happens to enzymes above their optimum temperature?

Answer 43

Enzymes denature ## Footnote Hydrogen bonds in the enzyme break, causing the enzyme and active site to lose shape, leading to no catalysis.

Question 44

What effect does a temperature below optimum have on enzyme activity?

Answer 44

Slower reaction ## Footnote Below optimum temperature, there is less energy, fewer collisions, and a slower reaction.

Question 45

What is the optimum pH range for many enzymes in the body?

Answer 45

Between 7 and 8 ## Footnote This range corresponds to the pH of most body cells and blood.

Question 46

What is a specific example of an enzyme with an extreme optimum pH?

Answer 46

Pepsin ## Footnote Pepsin is a stomach enzyme with a very low optimum pH, around 1-2.

Question 47

How does pH affect the charge on the active site of an enzyme?

Answer 47

It changes the charges ## Footnote Changes in pH can affect the ability of substrates to bind to the active site.

Question 48

What happens to the carboxyl group of an amino acid at low pH?

Answer 48

It is uncharged ## Footnote At high pH, it donates H+ and becomes negatively charged.

Question 49

How does substrate concentration affect the rate of reaction?

Answer 49

Increase in rate of collisions ## Footnote Higher substrate concentration leads to more collisions and an increased reaction rate.

Question 50

What happens if the substrate concentration is too high?

Answer 50

No more active sites available ## Footnote Increasing substrate concentration will no longer affect the rate of reaction.

Question 51

What is the effect of increasing enzyme concentration on the reaction rate?

Answer 51

Increases reaction rate ## Footnote More enzyme concentration leads to more collisions and an increased reaction rate.

Question 52

What occurs if the enzyme concentration is too high?

Answer 52

Too many free active sites ## Footnote The rate of reaction will no longer increase when there are too many active sites compared to substrate molecules.

Question 53

Fill in the blank: The optimum conditions for protease, an enzyme, are around pH _______ in the stomach.

Answer 53

1-2