10 - glycolysis and redox reactions

Question 1

what is a redox reaction?

Answer 1

electron transfers provide most of the energy of living things.

reduction - oxidation (redox) reactions are coupled.

Question 2

what is oxidation?

Answer 2

oxidation is loss of electrons, e.g. the addition of oxygen or the removal of hydrogen

Question 3

what is reduction?

Answer 3

reduction is gain of electrons, e.g. the addition of hydrogen or the removal of oxygen.

Question 4

what is a H+ proton?

Answer 4

a hydrogen atom without its electron e-

Question 5

what is a hydride ion H- ?

Answer 5

is a hydrogen with 2 electrons e-

Question 6

what do biological redox reactions often use?

Answer 6

electron carriers

Question 7

what is happenes to glucose to release energy?

Answer 7

it is oxidised

Question 8

what are the three stages of glucose oxidation?

Answer 8

1. glycolysis
2. the citric acid cycle
3. electron transport chain

Question 9

what is glycolysis?

Answer 9

the splitting of sugar

it can happen without oxygen in the cytoplasm of the cell.

Question 10

what is the initial investment of ATP in glycolysis and net production?

Answer 10

initial investment is 2 molecules of ATP, 4 ATP are formed

the net production is 2 ATP

Question 11

advantages of glycolysis

Answer 11

• rapid release of energy from glucose
• Doesn’t require oxygen
• produces pyruvate and lactate from other pathways (TCA cycle) and tissues (skeletal and cardiac muscle)

Question 12

disadvantages of glycolysis?

Answer 12

• not much ATP produced
• reduces available NAD+ - can end up with a shortage of this cofactor
• metabolic acidosis from proton build up due to lack of cellular buffering (pyruvate to lactate retards acidosis rather than contributes)

Question 13

what is the fate of pyruvate if oxygen is present?

Answer 13

if oxygen is present (aerobic), pyruvate enters the TCA cycle = complete oxidation of glucose

Question 14

what happens to pyruvate if no oxygen is present?

Answer 14

if no oxygen present (anaerobic) pyruvate converted to ethanol (plants) or lactate.

fermentation = incomplete oxidation of glucose

Question 15

where is lactate produced?

Answer 15

in skeletal muscle and red blood cells.

Question 16

where is lactate transported to as fuel source?

Answer 16

other tissues, especially cardiac muscle.

Question 17

what is gluconeogenesis?

Answer 17

synthesis of glucose or glycogen from non-carbohydrate source substrates in liver.