Enzymes

Question 1

What constitutes cellular metabolism?

Answer 1

Chemical reactions that take place in cells, maintaining the living state of the cells and organisms

Question 2

Participating molecules in cellular metabolism are known as what?

Answer 2

Metabolites

Question 3

What are the two types of reactions in cells?

Answer 3

Anabolic and catabolic

Question 4

Define endergonic

Answer 4

A reaction requiring an energy input

Question 5

Define exergonic

Answer 5

A reaction that releases energy

Question 6

What is an anabolic reaction?

Answer 6

A reaction that consumes energy while synthesising compounds
Energy consumed by the reaction is stored in the chemical bonds
Forms more complex molecules
FORMS BONDS

Question 7

What is a catabolic reaction?

Answer 7

A chemical reaction that releases energy when chemical bonds are broken
The energy released is used within the cell for other reactions
More simple compounds
BREAKS BONDS

Question 8

What are enzymes?

Answer 8

Molecules that act as catalysts to speed up biological reactions

Question 9

Are enzymes consumed doing biological reactions?

Answer 9

No, and they may keep working

Question 10

The compound on which an enzyme acts is known as a what?

Answer 10

Substrate

Question 11

What is the structure of an enzyme?

Answer 11

Enzymes are proteins, with an active site where the substrate binds
They are substrate specific

Question 12

How are enzymes named?

Answer 12

They typically end in -ase, and can be named after their substrate
Eg- an enzyme working on lactose may be lactase

Question 13

Where does substrate modification occur?

Answer 13

At the active site

Question 14

What is a high specificity enzyme?

Answer 14

An enzyme that will only bind with a single type of substrate

Question 15

What is a low specificity enzyme?

Answer 15

An enzyme that will bind with a range of related substrates

Question 16

When a substrate bonds to an enzyme’s active site, an ___________________ is formed

Answer 16

Enzyme-substrate complex

Question 17

How do enzymes work?

Answer 17

They charge molecular energy
A substrate requires activation energy to charge. Enzymes reduce the activation energy of a reaction, therefore increasing the rate of reaction (speeding it up)
They can either break down a substrate into two or more products or add two or more substrates together

Question 18

What is activation energy?

Answer 18

Before a substrate can charge it must overcome an energy barrier. This is known as activation energy
The larger the activation energy the slower the reaction

Question 19

What is the lock and key model?

Answer 19

Proposes that the the substrate must ‘fit’ into the enzyme’s activation site (it must be compatible) in order to be acted upon

Question 20

What is the induced fit model?

Answer 20

Two substrate molecules drawn into an active site and the enzyme will change shape to combine the two substrates
The enzyme returns to its normal shape

Question 21

What is a co-enzyme?

Answer 21

A chemical compound that can take up space in an active site, allowing certain reactions to occur

Question 22

What is a competitive inhibitor?

Answer 22

A chemical compound that can ‘mimic’ the molecules that fit in an active site.It will stop the enzyme working by preventing substrates binding to the active site

Question 23

What is a non-competitive inhibitor?

Answer 23

A form on Inhibitor molecule that will bind to other parts of an enzyme (not the active site)
This is known as a allosteric site
The pressen if allosteric compound can change the structure of an enzyme, thus layering the active site and rendering the enzyme inoperable

Question 24

How are enzymes affected by temperature?

Answer 24

Enzyme activity increases with higher temperatures

Once the temperature gets too high, enzyme denaturation will occur and the enzyme will cease to function

Question 25

Define denaturation

Answer 25

A process in which proteins or nucleic acids lose their structure, often rendering them unable to function

Question 26

How are enzymes affected by pH

Answer 26

Extremes of pH away from the enzyme optimum can result in enzyme denaturation

Question 27

How are enzymes affected by enzyme concentration?

Answer 27

The rate of reaction will continue to increase with an increase in enzyme concentration
The rate this increases at will stop only depending on substrate concentration

Question 28

How are enzyme affected by substrate concentration?

Answer 28

The rate of reaction increases and the plateaus with increasing substrate concentration
Assuming a fixed rate of enzymes

Question 29

What is a metabolic pathway?

Answer 29

A metabolic pathways refers to chemical processes that are linked by producing substances that may drive, or be needed In the ‘next step’
The process will produce a product that is necessary for cell survival
Most metabolic pathways are enzyme driven
Eg- A —>B —>C. (B is necessary for step C)

Question 30

What is a cyclic metabolic pathway?

Answer 30

The function of a cyclic metabolic pathway is to produce a substrate that will be used again and again.
They usually involve a number of intermediates and products produced in the pathway may be distributed out of the cycle and used in the cell