12.1 Glycolysis

Question 1

What do cells use as an immediate energy source

Answer 1

ATP

Question 2

What are the two forms of cellular respiration

Answer 2

1. Aerobic respiration

2. Anaerobic respiration

Question 3

What is aerobic respiration

Answer 3

Requires oxygen and produces carbon dioxide, water and much ATP

Question 4

What is anaerobic respiration

Answer 4

Takes place in the absence of oxygen and produces lactate in animals, or ethanol and carbon dioxide in plants/fungi. In both cases, little ATP is formed

Question 5

What are the 4 stages of aerobic respiration

Answer 5

1. Glycolysis - The splitting of the 6 carbon glucose molecule into two 3-carbon pyruvate molecules
2. Link reaction - The 3 carbon pyruvate molecules enter a series of reactions which leads to the formation of acetylcoenzyme-A, a 2-carbon molecule
3. Krebs cycle - the introduction of acetylcoenzyme-A into a cycle of oxidation-reduction reactions that yield some ATP and a large quantity of NAD and FAD
4. Oxidative phosphorylation - The use of electrons, associated with reduced NAD and FAD, released from the krebs cycle to synthesis ATP with water as a by-product

Question 6

Where does glycolysis occur

Answer 6

In the cytoplasm of cells

Question 7

What are the four stages of glycolysis

Answer 7

1. Phosphorylation of glucose to glucose phosphate.
2. Splitting of phosphorylated glucose
3. Oxidation of triose phosphate
4. The production of ATP

Question 8

What happens during the phosphorylation of glucose to glucose phosphate

Answer 8

Before glucose can be split in two, it must be made more reactive which is done by the addition of two phosphate molecules.

The phosphate molecules come from the hydrolysis of two ATP molecules to ADP. This provides the energy for the phosphorylation of glucose as well as lowering the activation energy for the enzyme-controlled reactions that follow

Question 9

What happens during the splitting of phosphorylated glucose

Answer 9

Each glucose molecule is split into two 3-carbon molecules known as triose phosphate

Question 10

What happens during the oxidation of triose phosphate

Answer 10

Hydrogen is removed from each of the two triose phosphate molecules and transferred to a hydrogen-carrier molecule known as NAD to form reduced NAD

Question 11

What happens during the production of ATP

Answer 11

Enzyme controlled reactions convert each triose phosphate molecule into the 3-carbon molecule pyruvate. In the process, two molecules of ATP are regenerated from ADP

Question 12

What are the overall energy yields from glycolysis

Answer 12

1. Two molecules of ATP (4 but 2 are used in the phosphorylation of glucose)
2. Two molecules of reduced NAD
3. Two molecules of pyruvate

Question 13

What is glycolysis

Answer 13

A universal feature of every living organism