Respiration

Question 1

glycolysis

Answer 1

occurs in cytoplasm
glucose is phosphorylated by 2 ATP to form glucose phosphate
glucose phosphate split into 2x triose phosphate (lysis)
triose phosphate is oxodised to pyruvate, removing a hydrogen ion , transferring it to NAD (2x ATP used)

Question 2

link reaction

Answer 2

if o2 is available, pyruvate enters the mitochondrial matrix by active transport
pyruvate is oxidised to form acetate
2x co2 removed ( decarboxylation)
acetate combines with co enzyme A to form acetyl coenzyme A
1 molecule of NAD reduced to NADH
LR occurs twice per glucose molecule

Question 3

krebs cycle

Answer 3

occurs in matrix of mitochondria
provides continuous supply of electrons to ETC
acetyl coA (2C) combines with oxaloacetate (coenzyme A is released) to form 6C compound- citrate
oxidation of citrate releases H atoms that reduce NAD
Co2 is released, forming a 5C molecule
atp is formed from adp + pi
another Co2 molecule is released from 5C forming oxaloacetate,
2x NAD and 1x FAD are reduced and carry h atoms (H ions and electrons) to ETC
reduced = NADH/FADH

Question 4

oxidative phosphorylation

Answer 4

occurs in inner mitochondrial membrane
1- NADH deposits high energy electrons onto first molecule carrier and split H atoms to H+ and e-
2- high energy e- enter ETC and release energy as they move down
3- energy used to transport protons (H+) across inter mitochondrial membrane into intermembrane space
4- conc gradient of protons is established
5-protons travel down gradient, to matrix, through ATP synthase by fac. diffusion, giving up energy as they pass through, for ADP to be phosphorylated to ATP
6-oxygen is the terminal electron acceptor as it combines 2 electrons and 2 H+ to form water
electrons cannot travel down ETC if there is no o2 to accept them

Question 5

anaerobic respiration

Answer 5

occurs when there is not enough o2 to respire aerobically, in cytoplasm
lactate- pyruvate from glycolysis is reduced to form lactate
oxidises NADH (to NAD) so that it can be used in glycolysis and keep producing ATP
NAD used in glycolysis to reduce triose phosphate to NADH and pyruvate
build up of lactate causes muscle cramps (denatures enzymes) which can broken down when o2 becomes available

plants+ yeast- pyruvate in glycolysis is converted into ethanol and carbon dioxide by NADH transferring its hydrogens to ethanol
oxidises NADH (to NAD) so that it can be used in glycolysis and keep producing (2x) ATP

Question 6

role of coenzymes

Answer 6

NAD and FAD are reduced- accept H atoms
electrons from reduced NAD and FAD are transferred to ETC
movement of H+ ions down protein gradient provides energy required for ATP synthesis

Question 7

respirometer

Answer 7

used to measure rate of resp by measuring rate of exchange of o2 and or co2

organisms are placed in one tube and non living material of the same mass is placed in another tube

as organisms respire, they take o2 from air and give out co2 (co2 absorbed by soda lime)

removal of o2 from air reduces volume and pressure in tube, so fluid moves towards organisms

distance moved by fluid in tube only affected by o2 as co2 is absorbed by soda lime

if o2 is absorbed and organisms anaerobically respires, they will produce co2, will increase pressure and so fluid will move other way (away)

Question 8

yield

Answer 8

glycolysis- 2xATP 2x reduced NAD 2x pyruvate
link- 2x acoA 2x Co2 2x reduced NAD
krebs- 2x reduced NAD 1x reduced FAD 1x ATP
ETC- 32x ATP, 1x H20

Question 9

respirometer

Answer 9

volume of oxygen absorbed by organisms

volume of liquid= pi r2 x length

Question 10

respirometer tube open

Answer 10

allow for pressure changes in equipment
to allow pressure to equilibrate
wait for rate of resp to become constant

Question 11

anaerobic leave for 10 mins

Answer 11

use up oxygen before it starts