respiration

Question 1

where does glycolysis occur?

Answer 1

cytoplasm

Question 2

what is the stage when glucose is phosphorylated into hexose diphosphate called?

Answer 2

glucose activation

Question 3

list the order of stages in glycolysis

Answer 3

glucose-> hexose diphosphate-> TP-> GP-> pyruvate

Question 4

at what stages are ATP used up and made, and NADH used and made?

Answer 4

ATP used: glucose -> hexose diphsphate (x2)
ATP made: TP -> GP (x2) and GP-> pyruvate (x2)
NADH made: TP-> GP

Question 5

what happens during anaerobic respiration in animals?

Answer 5

-TP is converted straight to pyruvate (making ATP and NADH)
- pyruvate is reduced to lactate (NADH is converted back to NAD as H is used in this)
- allows glycolysis to continue and a small amount of ATP (x2) to be produced

Question 6

what happens during anaerobic respiration in plants?

Answer 6

• TP converted to pyruvate (making ATP and NADH)
• pyruvate is decarboxylated to make ethanal (CO2 removed)
• NADH reduces ethanal to ethanol
• allows glycolysis to continue etc.

Question 7

where in the cell does the link reaction and the Kreb’s cycle occur?

Answer 7

matrix of mitochondria

Question 8

what happens during the link reaction?

Answer 8

• pyruvate decarboxylated to make acetate
• enzyme coA added to convert it to acetyl coA
• NAD reduced to NADH

Question 9

how many NADH, FADH2 and ATP are made per glucose molecule?

Answer 9

• there are 2x pyruvate made per glucose molecule
• 3x2= 6 NADH
• 1x2= 2 FADH2
• 1x2= 2 ATP

Question 10

explain the stages of oxidative phosphorylation

Answer 10

• NADH from glycolysis/link/krebs travels to inner membrane and is oxidised to NAD
• the H atom is split into H+ and an electron
• H+ is pumped across inner membrane to inter-membrane space
• e is passed along electron transport chain, where the energy released from the high energy e’s is used to fuel proton pumps
• eventually, e is passed onto final electron acceptor, O2, and water is made (H++O2+e-)
• because there is now an electrochemical gradient between the matrix and the inter-membrane space, H+ flows back into the matrix through ATP synthase by facilitated diffusion (chemiosmosis)
• ATP generated

Question 11

why does FADH2 produce less ATP molecules in the ETC than NADH?

Answer 11

• FADH2 has lower energy e’s
• process starts at 2nd proton pump
• only 2 (instead of 3) ATP made