Unit 2.1 Metabolic Parhways

Question 1

What is metabolism?

Answer 1

Metabolism is the collective term for the thousands of biochemical reactions that occur within a living cell.

Question 2

What are metabolic pathways?

Answer 2

Metabolic pathways are integrated and controlled pathways of enzyme-catalysed reactions within a cell.

For example, the breakdown of glucose to pyruvate is a metabolic pathway.

Question 3

What is metabolism?

Answer 3

Metabolism is the collective term for the thousands of biochemical reactions that occur within a living cell.

Question 4

What are metabolic pathways?

Answer 4

Metabolic pathways are integrated and controlled pathways of enzyme-catalysed reactions within a cell.

Example: The breakdown of glucose to pyruvate is a metabolic pathway.

Question 5

What are the two types of metabolic pathways?

Answer 5

The two types of metabolic pathways are:
1. Anabolic (Synthesis)
2. Catabolic (Degradation)

Question 6

What is an anabolic reaction?

Answer 6

An anabolic reaction is the buildup of larger complex molecules from simpler building blocks. Energy is required for these reactions.

Example: Anabolic steroids are sometimes used by athletes to increase muscle mass.

Question 7

What is a catabolic reaction?

Answer 7

A catabolic reaction is the breakdown of larger complex molecules into smaller ones. Energy is released during these reactions.

Question 8

What are metabolic pathways controlled by?

Answer 8

Metabolic pathways are controlled by the presence or absence of particular enzymes and the regulation of the rate of reaction of key enzymes.

Question 9

What is the role of enzymes in metabolic pathways?

Answer 9

Enzymes control the rate of reaction in metabolic pathways.

Question 10

How are Metabolic pathways controlled

Answer 10

Question 11

What kind of steps can metabolic pathways have

Answer 11

Question 12

Irreversible

Answer 12

Question 13

Reversible

Answer 13

Question 14

Alternative route

Answer 14

Question 15

What are reversible steps in metabolic pathways?

Answer 15

Reversible steps allow intermediates to convert back to previous intermediates.

Question 16

Can you give an example of a reversible step?

Answer 16

During fermentation in animal cells, pyruvate can be converted to lactate and vice versa.

Example: Pyruvate ↔ Lactate

Question 17

What are irreversible steps in metabolic pathways?

Answer 17

Irreversible steps occur when it is favorable for the cell, maintaining low concentrations of certain metabolites.

Question 18

Can you give an example of an irreversible step?

Answer 18

During glycolysis, glucose is irreversibly converted to an intermediate.

Example: Glucose → Intermediate

Question 19

What are alternative routes in metabolic pathways?

Answer 19

Alternative routes allow certain steps to be bypassed in metabolic pathways.

Question 20

Can you give an example of an alternative route?

Answer 20

Glucose can be converted to sorbitol when the cell has a high concentration of glucose.

Example: Glucose → Sorbitol

Question 21

What is induced fit?

Answer 21

Induced fit is the process where the active site changes its shape to fit the substrate, ensuring close contact and increasing the chances of a reaction.

Question 22

What does high affinity mean in the context of enzymes?

Answer 22

High affinity means that substrate molecules are strongly attracted to the active site.

Question 23

What happens to the affinity of products in enzyme reactions?

Answer 23

Products have a low affinity for the active site, encouraging them to leave, which allows the enzyme to be reused.

Question 24

Diagram of indices fit

Answer 24

Question 25

What is activation energy?

Answer 25

Activation energy is the energy needed to break the chemical bonds allowing a chemical reaction to take place.

Question 26

How do enzymes affect activation energy?

Answer 26

Enzymes lower activation energy.

Question 27

What is a metaphor for activation energy?

Answer 27

It is like rolling a boulder down a hill, but having to push it up a small hump first.

Question 28

What happens after the initial push in the boulder metaphor?

Answer 28

After the initial push, the boulder rolls on.

Question 29

How do enzymes relate to the boulder metaphor?

Answer 29

Enzymes make the small hump even smaller.

Question 30

What is embedded in cell membranes?

Answer 30

Protein pores, pumps, and enzymes are embedded in membranes.

Question 31

How does increasing substrate concentration affect the rate of reaction?

Answer 31

Increasing substrate concentration increases the rate of a reaction until a certain point is reached.

Question 32

What happens to the reaction rate at low substrate concentration?

Answer 32

At low substrate concentration, the reaction rate is low since there are too few substrate molecules to make maximum use of all active sites.

Question 33

What is concentration?

Answer 33

Concentration refers to the amount of a substance in a given volume. ## Footnote Example: A higher concentration of substrate can lead to a faster reaction rate.

Question 34

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

Answer 34

Increasing substrate concentration increases the rate of reaction as more active sites become involved. ## Footnote Example: As substrate concentration rises from 0 to 10, the reaction rate increases.

Question 35

What happens to the reaction rate as substrate concentration increases?

Answer 35

The reaction rate levels off as there is further increase in substrate concentration.

Question 36

Why does the reaction rate level off?

Answer 36

All active sites have become occupied.

Question 37

What factors affect enzyme activity?

Answer 37

Factors affecting enzyme activity include temperature, pH, substrate concentration, and inhibitors.

Question 38

What is an inhibitor?

Answer 38

An inhibitor acts by slowing down or stopping the rate at which an enzyme-controlled reaction can work.

Question 39

What are the types of inhibitors?

Answer 39

There are three types of inhibitors: competitive, non-competitive, and end point inhibition.

Question 40

What are competitive inhibitors?

Answer 40

Competitive inhibitors bind at the active site, preventing the substrate from binding.

Question 41

How do competitive inhibitors function?

Answer 41

Competitive inhibitors are similar in shape to the substrate, allowing them to fit into the active site.

Question 42

What are examples of competitive inhibitors?

Answer 42

Examples of competitive inhibitors include alcohol, statins, and methotrexate.

Question 43

How does ethanol act as a competitive inhibitor?

Answer 43

Ethanol is a competitive inhibitor to antifreeze for the enzyme alcohol dehydrogenase, treating antifreeze poisoning.

Question 44

How does methotrexate act as a competitive inhibitor?

Answer 44

Methotrexate is a chemotherapy drug that inhibits an enzyme involved in the synthesis of DNA and RNA in cancer cells.

Question 45

How do statins work as competitive inhibitors?

Answer 45

Statin drugs lower cholesterol levels by inhibiting the enzyme HMG-CoA reductase, involved in cholesterol synthesis.

Question 46

Is competitive inhibition reversible?

Answer 46

Yes, competitive inhibition is reversible and can be reversed by increasing substrate concentration.

Question 47

What are non-competitive inhibitors?

Answer 47

Non-competitive inhibitors bind away from the active site but change the shape of the active site, preventing the substrate from binding.

Question 48

What are examples of non-competitive inhibitors?

Answer 48

Examples of non-competitive inhibitors include lead and acetylcholinesterase inhibitors.

Question 49

How does lead act as a non-competitive inhibitor?

Answer 49

Lead acts as a non-competitive inhibitor of many enzymes in the human body, mimicking other metals involved in biological processes.

Question 50

How do acetylcholinesterase inhibitors function?

Answer 50

Acetylcholinesterase inhibitors increase the concentration of a neurotransmitter in the brain, improving cognitive function in Alzheimer's patients.

Question 51

What is the effect of cyanide as a non-competitive inhibitor?

Answer 51

Cyanide binds to an enzyme involved in the release of ATP by respiration, affecting tissues that depend on aerobic respiration.

Question 52

What is feedback inhibition?

Answer 52

Feedback inhibition occurs when the end-product in the metabolic pathway reaches a critical concentration.

Question 53

What happens when the end-product reaches a critical concentration?

Answer 53

The end-product inhibits an earlier enzyme, blocking the pathway.

Question 54

What is the effect of feedback inhibition on the synthesis of the end-product?

Answer 54

It prevents further synthesis of the end-product.

Question 55

What are the enzymes involved in the metabolic pathway?

Answer 55

Enzyme 1, Enzyme 2, and Enzyme 3.