Aerobic Respiration

Question 1

what are the 4 stages of respiration?

Answer 1

• glycolysis
• link reaction
• Krebs Cycle
• oxidative phospharylation

Question 2

what are the 4 stages of glycolysis?

Answer 2

• phosphorylation of glucose to glucose phosphate
• splitting of glucose phosphate
• oxidation of triose phosphate
• production of ATP

Question 3

what happens during stage 1 of glycolysis?

Answer 3

• glucose is made more reactive by the addition of 2 phosphate molecules (phosphorylation)
• hydrolysis of 2 ATP molecules releases 2 phosphate molecules and 2 ADP molecules

Question 4

what happens during the second stage of glycolysis?

Answer 4

• splitting of phosphorylated glucose
• each glucose molecule is split into 2 3 carbon molecules called triose phosphate

Question 5

what happens during the third stage of glycolysis?

Answer 5

• hydrogen is removed from each of the 2 triose phosphate molecules and transferred to NAD to form reduced NAD

Question 6

what happens during the final stage of glycolysis?

Answer 6

• enzyme-controlled reactions convert each triose phosphate molecule into another 3 carbon molecule called pyruvate
• two molecules of ATP are regenerated from ADP

Question 7

where does glycolysis occur?

Answer 7

cytoplasm

Question 8

where does pyruvate go after glycolysis?

Answer 8

actively transported into the mitochondrial matrix through a transport protein

Question 9

what is the yield from glycolysis?

Answer 9

• two molecules of ATP
• two molecules of reduced NAD
• two molecules of pyruvate

Question 10

what type of phosphorylation takes place in glycolysis?

Answer 10

substrate-level phosphorylation

Question 11

why is the net production of ATP 2 in glycolysis?

Answer 11

4 molecules of ATP produced but 2 are used up in initial phosphorylation of glucose
4-2=2

Question 12

what happens during the link reaction?

Answer 12

• pyruvate is oxidised to acetate(2C). This reaction involved the decarboxylation of pyruvate (loses a CO2) and the dehydrogentaion of pyruvate (loses hydrogens)
• this happens to each pyruvate produced by the glucose
• the hydrogens are accepted by NAD to form reduced NAD which is later used to produce ATP
• 2 carbon acetate combines with coenzyme A to form acetylCoA (2C- acetyl coenzyme A)

Question 13

what is the summary equation for the link reaction?

Answer 13

pyruvate + NAD + CoA –> acetyl CoA + reduced NAD + CO2

Question 14

where does the link reaction take place?

Answer 14

mitochondrial matrix

Question 15

what can ATP be used for?

Answer 15

• active transport
• mitosis
• DNA replication

Question 16

what happens during the Krebs Cycle?

Answer 16

• acetyl CoA (2C) from the link reaction combines with 4C molecule (oxaloacetate) to form a 6C molecule (citrate) CoA goes back to the link reaction to be used again.
• citrate loses CO2(decarboxylation) and hydrogen(dehydrogentation) (hydrogen accepted by NAD to form NADH) to form a 5C molecule
• 5C molecule is then 4C molecule (oxaloacetate). Decarboxylation and dehydrogenation occurs produces one molecule of reduced FAD and two molecules of reduced NAD. ATP produced from direct transfer of phosphate from intermediate ADP compound (substrate level phosphorylation)
• citrate is converted back to oxaloacetate

Question 17

what are the products of Krebs cycle and where do they go?

Answer 17

• 1 CoA = reused in link reaction
• oxaloacetate = regenerated for use in next Krebs cycle
• 2 CO2 = released as a waste products
• 1 ATP = used for energy
• 3 reduced NAD = oxidative phosphorylation
• 1 reduced FAD = oxidative phosphorylation

Question 18

what is the order of events from 5 carbon molecule to 4 carbon molecule?

Answer 18

• removes CO2
• NAD –> reduced NAD
• ADP + Pi –> ATP
• FAD –> reduced FAD
• NAD –> reduced NAD