Aerobic and anaerobic respiration

Question 1

what is respiration

Answer 1

a series of enzyme-catalysed reactions which release chemical energy from organic molecules (usually glucose) inorder to synthesise ATP.

Question 2

what are the four main stages of the breakdown of glucose molecules to carbon dioxide and water

Answer 2

glycolysis
link reaction
krebs cycle
electron transport chain

Question 3

Info about glycolysis

Answer 3

takes place in cytoplasm, does not require oxygen and results in the net production of only 2 ATP.
involves the phosphorylation of glucose. glucose is split into 2 x 3-carbon triose phosphate molecules.
the 3C TP are then oxidised to 3C pyruvate releasing H atoms to be picked up by NAD to form reduced NAD.

Question 4

What is the glycolysis production

Answer 4

for each glucose molecule that enters glycolysis
2 ATP are used in phosphorylation, makes the glucose more reacted and able to split into 3C triose phosphate.
4 ATP are produced through substate phosphorylation giving a total of 2 ATP.
2 reduced NAD are produced as a result of the oxidation of 3Ctriose phosphate
2 Molecules of pyruvate produced (then enters link reaction)

Question 5

Info about link reaction

Answer 5

Pyruvate diffuses from the cytoplasm into the mitochondrial matrix.
here the 3C pyruvate is converted into 2C acetate.
Carbon dioxide is lost followed by the removal of hydrogen by the reduction of NAD.
The acetyle group then combines with co-enzyme A o produce acetyl co-enzyme A.

Question 6

products of the link reaction

Answer 6

2 x Carbon dioxide - removed using the enzyme decarboxylase
2 x reduced NAD - hydrogen passed on to hydrogen acceptor using enzyme dehydrogenase
2 x Acetyle co enzyme A which enters the krebs cycle

Question 7

Info about krebs cycle

Answer 7

A series of decarboxylations (removal of carbon dioxide using decarboxylase) and dehydrogenation (removal of hydrogen using dehydrogenase).
the 2C acetate combines with a 4C compound to make a 6C compound.
the Co-enzyme A is regenerated and passed back to the link reaction.
the 4C compound is regenerated.

Question 8

productions in krebs cycle

Answer 8

6 reduced NAD
2 Reduced FAD
2 x ATP (between 5C and 4C)
4 x CO2

Question 9

How many ATP is made thorugh oxidative phosphorylation

Answer 9

32

Question 10

Total of ATP made from glyoclysis, link reaction, krebs cycle and oxidative phosphorylation

Answer 10

38

Question 11

what happens if there is no oxygen

Answer 11

reduced NAD cannot be reoxidised and so are unable to pick up more hydrogen, oxidative phosphorylation will not take place. meaning, link reaction and krebs cycle cannot take place.

Question 12

what happens in glycolysis in anaerobic respiration

Answer 12

takes places as usual. pruvate is made and a small amount of ATP (2 ATPP) from substrate level phosphorylation

Question 13

what happens if pyruvate levels were allowed ot build up

Answer 13

it would stop glycolysis and inhibit ATP production

Question 14

solutions to the stopping of glycolysis and inhibiting ATP production

Answer 14

alcholic fermentation used by fungi and plants (forms ethanol and carbon dioxide)
Lactic fermetnations used by animals forms lactate

Question 15

Info about alcholic fermentation

Answer 15

first, CO2 is removed from pyruvate to produce ethanal.
alcohol dehydrogenase converts ethanal to ethanol by adding hydrogen taken from reduced NAD.
process used by humans for many thousands of years to produce risen breads and alcohol for drinking

Question 16

Info about lactate fermentation

Answer 16

first, pyruvate becomes lactate when a hydrogen is taken from a reduced NAD

Question 17

how many molecules of ATP for each glucose molecule in anaerobic respiration

Answer 17

2 molecules of ATP

Question 18

calculate energy effieciency for aerobic respiration

Answer 18

30kJ x 38 = 1140kJ
divide by 2880 kJ and then x 100.
40% energy effieciency, the rest of the energy is lost as heath

Question 19

calculate energy efficiency for anaerobic respiration

Answer 19

30kJ x 2 = 60kJ
divide by 2880 kJ and then x by 100.
2% energy effieciency

Question 20

What are the alternative energy sources

Answer 20

lipids and proteins
lipids are made of fatty acids and glycerol.
glycerol is converted into a 3C sugar, this enters the kreb cycle via triose phosphate
fatty acid chains are split into 2C fragments which eneter krebs cycle as acetyl coenzyme A
proteins are made of amino acids, will ojly be used if the body is in starvation mode when all carbohydrates and lipids are used up.
the amino acids are deaminated. the NH2 gorup is removed and converted into urea.
urea is then excreted through kidneys.
the organic acid left is fed into krebs cycle