Human Cells Unit 1 KA 6

Question 1

What is Metabolism?

Answer 1

Metabolism is all the chemical reactions that occur within the human body

Question 2

What is involved in Metabolic pathways? (2)

Answer 2

Metabolic pathways involve the…
1) BUILDING UP of molecules
2) BREAKING DOWN of molecules

Question 3

What do Anabolic pathways involve, what does it require?

Answer 3

Anabolic pathways involve biosynthetic (building up) processes
It requires energy

Question 4

What do Catabolic pathways involve, what does it release?

Answer 4

Catabolic pathways involve the breakdown of molecules, it releases energy

Question 5

How is the Rate of a chemical reaction indicated?

Answer 5

The rate of a chemical reaction is indicated by the quantity of chemical change that occurs per unit time

Question 6

What is the Activation energy?

Answer 6

The activation energy is the energy required to break chemical bonds in the reactant chemicals

Question 7

What is the Transition state?

Answer 7

The transition state is when bonds break because the molecules of the reactant have absorbed enough energy to make them unstable

Question 8

In what form does the energy input of a reaction often occur in?

Answer 8

The energy input of a reaction often occurs in the form of heat energy

Question 9

A reaction will only proceed at a high rate if the chemicals are raised to a ____ ____

(Fill in the blank)

Answer 9

A reaction will only proceed at a high rate if the chemicals are raised to a high temperature

Question 10

What is a Catalyst? (3)

Answer 10

A catalyst is a substance that -
1) Lowers the activation energy
2) Speeds up reaction rate
3) Remains unchanged

Question 11

What is an Enzyme?

Answer 11

An enzyme is a Biological catalyst

(Made of protein)

Question 12

An Enzyme contains an ____ ____
which is a ____ ____

(Fill in the blanks)

Answer 12

An enzyme contains an active site which is a specific shape

Question 13

Why does an Enzyme only act on one substrate?

Answer 13

An enzyme only acts on one substrate because the enzyme is specific to its substrate
The substrate is complementary to the enzymes active site

Question 14

Substrate molecules have a ____ affinity for the active site

(Fill in the blank)

Answer 14

Substrate molecules have a high affinity for the active site

Question 15

Products have a ____ affinity for the active site

(Fill in the blank)

Answer 15

Products have a low affinity for the active site

Question 16

What happens after the Product leaves the active site?

Answer 16

After the product leaves the active site, the enzyme is left free to repeat the process with new molecules of substrate

Question 17

What is the structure of the Active site like?

Answer 17

The structure of the active site is flexible and dynamic

Question 18

What is Induced fit?

Answer 18

Induced fit is when the active site changes shape to better fit the substrate after the substrate binds

Question 19

What does Induced fit increase the chance of?

Answer 19

Induced fit increases the chance of the reaction taking place

(Ensures active site comes in close contact with substrate)

Question 20

When a reaction involves 2+ substrates, why is the shape of the Active site important?

Answer 20

When a reaction involves 2+ substrates, the shape of the active site is important as it determines the orientation of the reactants

Question 21

What does the Enzyme do to the activation energy?

Answer 21

The enzyme weakens chemical bonds in the reactants, lowering the activation energy

Question 22

What does an Enzyme require to function efficiently? (4)

Answer 22

A suitable…
1) Temperature
2) pH
3) Substrate concentration
4) Enzyme concentration

Question 23

What are Inhibitors?

Answer 23

Inhibitors are a substance that decreases the rate of an enzyme controlled reaction

Question 24

As Substrate concentration increases, rate of reation ____

(Fill in the blank)

Answer 24

As substrate concentration increases, rate of reaction increases

Question 25

Why does the rate of reaction remains constant if all active sites are occupied?

Answer 25

If all active sites are occupied then the rate of reaction remains constant because **enzyme concentration** is the **limiting factor**

Question 26

How can **Metabolic pathways** be controlled? (3)

Answer 26

1) Presence of an enzyme 2) Absence of an enzyme 3) Key enzymes regulating the rate of the reaction

Question 27

What does the direction of a reaction depend on?

Answer 27

The direction of a reaction depends on the concentrations of the reactants and products

Question 28

Describe a **Competitive inhibitor** - (3)

Answer 28

1) Similiar molecular structure to substrate 2) Competes with substrate for enzyme active site 3) Binds to active site, prevents substrate from binding

Question 29

How can **Competitive inhibition** be reversed?

Answer 29

Competitive inhibition can be reversed by **increasing substrate concentration**

Question 30

Describe a **Non-competitive inhibitor** - (3)

Answer 30

1) Does not have a similiar molecular structure to substrate 2) Binds to **allosteric/regulator site**, changing active site shape to prevent substrate from binding 3) Can NOT be reversed

Question 31

What happens to reaction rate if the regulatory molecule is an **Activator**?

Answer 31

If the regulatory molecule is an activator, reaction rate **increases**

Question 32

What happens to the reaction rate if the regulatory molecule is an **Inhibitor**?

Answer 32

If the regulatory molecule is an inhibitor, reaction rate **decreases**

Question 33

What is **Feedback inhibition**?

Answer 33

Feedback inhibition is when the end product reaches a critical concentration and binds to an enzyme that catalyses a reaction earler in the pathway, inhibiting it and blocking the pathway

Question 34

What does **Feedback inhibition** prevent?

Answer 34

Feedback inhibition prevents further synthesis of the end product