Chapter 8- Cellular metabolism (1)

Question 1

What is a metabolic pathway?

Answer 1

A series of chemical reactions occurring within a cell.

Question 2

What part of the pathway is modified by a sequence of chemical reactions?

Answer 2

The initial chemical (metabolite)

Question 3

The reactions in a metabolic pathway are catalysed by?

Answer 3

Enzymes

Question 4

What is the main aim of metabolic pathways?

Answer 4

To generate ATP

Question 5

If ATP production falls by 5- 10%, then what will happen to the cell?

Answer 5

The cell is likely to die

Question 6

ATP depletion may trigger what?

Answer 6

Apoptosis- where a cell realises that it hasn’t got enough energy and selectively kills itself.

By selectively killing itself, the surrounding cells are now not competing with that cell so the probability of those cells surviving is higher.

Question 7

What are the two metabolic pathways?

Answer 7

1- Catabolic pathways

2- Anabolic pathways

Question 8

What do catabolic pathways do?

Answer 8

Break down food into smaller molecules with the release of energy.

This results in ATP production and transfer of energy

Breaks down macromolecules

Question 9

What do anabolic pathways do?

Answer 9

Anabolic pathways are biosynthetic and use the energy released by catabolism to synthesize molecules that the cell requires

Question 10

What is biosynthetic?

Answer 10

The production of complex molecules within living organisms or cells.

Question 11

How do cells release energy in relation to food molecules?

Answer 11

Cells release energy by the oxidation of food molecules.

Question 12

How is the energy released by the oxidation of food molecules stored?

Answer 12

It is stored in the chemical bonds of a set of carrier molecules.

Question 13

What do carrier molecules include?

Answer 13

1- ATP- adenosine triphosphate

2- NADH- nicotinamide adenine dinucleotide

Question 14

ATP is a nucleotide that contains 3 main structures:

Answer 14

1- Nitrogenous base (adenine)

2- Ribose sugar

3- 3 phosphate groups bound to the ribose

Question 15

How is ATP broken down into ADP?

Answer 15

Through the process of hydrolysis- addition of a water molecule

ADP is formed when one phosphate is removed from ATP.

Question 16

Electron carriers are involved in what type of reactions?

Answer 16

Redox reactions- carrying electrons from one reaction to another.

Question 17

What is the process of glycolysis?

Answer 17

Converts a 6 carbon glucose molecule into two 3 carbon molecules of pyruvate.

Question 18

Where does glycolysis occur?

Answer 18

In the cytoplasm

Question 19

What is the net gain of glycolysis?

Answer 19

2 molecules of ATP and 2 molecules of NADH for each molecule of glucose

Question 20

How is ATP formed?

Answer 20

By ADP and phosphate coming together.

Question 21

There is fast ATP production during glycolysis, but has a low what?

Answer 21

Low yield

Question 22

When there is no oxygen available, pyruvate turns into what?

Answer 22

Lactate. This reaction is catalysed by lactate dehydrogenase

Question 23

When does the conversion from pyruvate to lactate occur?

Answer 23

When the intake of oxygen cannot match the amount of energy we are using up.

Question 24

When there is oxygen available, what is pyruvate converted to?

Answer 24

Acetylecoenzyme A and carbon dioxide is formed.

This is called a transition reaction and occurs in the mitochondria.

Question 25

What is a key intermediate to transfer 2 carbon atoms into the Krebs cycle?

Answer 25

AcetylCOA