respiration Flashcards
glycolysis
in the cytoplasm
Phosphorylation of glucose (6c) to glucose phosphate (6c) using hydrolysis of atp
hydrolysed to 2 triose phosphates (2x 3c)
oxidised to 2 pyruvate
2 NAD reduced and net gain of 2 atp
what happens after glycolysis if anaerobic
pyruvate to lactate or ethanol
oxidising reduced NAD so NAD regenerated
so glycolysis can continue allowing continued production of ATP
why does anaerobic produce less atp per molecule of glucose than aerobic
only glycolysis involved which produces only 2 ATP
no oxidative phosphorylation which forms majority of ATP
link reaction
pyruvate AT to mitcho matrix
pyruvate oxidised to acetate
c02 produced
NAD picks up H = reduced NAD
acetate combines with coenzyme a forming acetyl coenzyme A
products per glucose in link reaction
2x acetylcoenzyme A
2 co2 released
2 reduced NAD
Krebs cycle
acetyl coenzyme A reacts with a 4c molecule
releasing coenzyme A
producing a 6c molecule that enters the Krebs cycle
series of redox reactions
4c molecule regenerated and
2x co2 is lost
coenzyme NAD FAD reduced
substrate level phosphorylation
ATP produced
products per glucose molecule in Krebs cycle
6 reduced NAD
2 reduced FAD
2 ATP
4 CO2
oxidative phosphorylation
cristae
reduced nad and fad oxidised to release h atoms
these split to protons and electrons
electrons transferred down ETC via redox
energy released by electrons used in the production of ATP from adp+PI
energy used by electron carriers to actively pump protons from matrix to inter membrane space
protons diffuse into matrix down electrochemical gradient via atp synthase
releasing energy to synthesise atp from adp pi
end of etc in matrix - oxygen is the final electron acceptor so P E 02 combine = water
how can a respirometer be used to measure the rate of aerobic respiration
measure o2 uptake
add set mass of single celled organism eg yeast to set conc of substrate eg glucose
add buffer to keep ph constant
add a chemical that absorbs co2 like NAOH
place in water bath at set temp and allow it to equilibrate
measure distance moved by coloured liquid in set time
why does liquid move (o2 uptake)
organisms respire aerobically - take in o2
co2 is given out but absorbedly NAOH
so volume of gas and pressure in container decreases
fluid in capillary tube moves down pressure gradient towards organism
why is respirometer apparatus left open for 10 minutes
allows apparatus to equilibrate
allow for overall pressure expansion and change
allow respiration rate of organism to stabilise
why airtight apparatus
prevents air entering or leaving
would change vol and pressure affecting liquid movement
what is an accurate way to measure volume of gas
use gas syringe
using respirometer to measure rate of anaerobic respiration
measure co2 release
same experiment as o2 one but remove chemical that absorbs co2
make conditions anaerobic by adding a layer of oil to stop oxygen diffusing in
add a chemical that absorbs o2
leave for an hour to allow o2 to be respired and used up
why does liquid move in the anaerobic respiration
yeast anaerobically respires releasing co2
so blouse of gas and pressure in container increases
fluid in capillary tube moves down a pressure gradient away from organism
how can redox indicator dyes eg methylene blue used to measure rate of respiration
redox indicator changes colour when accepts electrons and becomes reduced
take up hydrogens and get reduced modelling action of NAD AND FAD
add set volume of organism and respiratory substrate
add buffer keep ph contrant
place in water bath at set temp to equilibrate for 5 mins
add set volume methylene blue and shake
record time taken for colour to disappear
variables to control - methylene blue
volume of single celled organism
conc of rest substrate
temp
ph
why leave tubes in water bath for. 5 min
allow solutions to equilibrate and reach same temps water bath
control experiment for methylene blue
add methylene blue to dead yeast and all other conditions the same
shows change is due to respiration in organism
why to shake tubes with methylene blue
shaking - mixes it with oxygen
which oxidises methylene blue causing it to lose electrons
so methylene blue turns back to original blue colour
an error with methylene blue
subjective - determination of colour change
compare results to colour standard or use a colorimeter
