Please enable JavaScript.
Coggle requires JavaScript to display documents.
Respiration Practicals Redox Indicators - Coggle Diagram
Respiration Practicals
Redox Indicators
During Respiration
many
DEHYDROGENATION
reactions
hydrogen
atoms
removed
catalysed by
dehydrogenase
enzymes
Hydrogen atoms used to
REDUCE NAD/FAD
form reduced NAD/FAD
Redox Indicators
used to demonstrate
dehydrogenation
taking place
D: chemicals different colour when reduced compared to when oxidised
take place of NAD/FAD
Methylene Blue
when
REDUCED
= COLOURLESS
when
OXIDISED
=
BLUE
acts as HYDROGEN ACCEPTOR
Method
1.
CRUSH
soaked peas into a paste
using pestle and mortar
place in BOILING TUBE
Repeat with
BOILED
peas
make up
METHYLENE BLUE
of suitable concentration
add 2cm3 MB to
each boiling tube
place in WATER BATH
@ temp above 35°C
Results
higher temperatures
blue to colourless FASTER
dehydrogenase enzymes
more kinetic energy
form
more complexes
with substrate
boiled or too high temperatures
remain blue
enzymes would be
denatured
active site shape changed
unable to combine with substrate molecules
Dependent Variable
record
TIME TAKEN
for
COMPLETE LOSS of BLUE COLOUR
Questions
ensure results obtained in
short period of time?
peas were soaked
peas were ground up
dilute methylene blue
what causes MB
blue to colourless?
during respiration - hydrogen atoms released
accepted by MB - reduced
colour change blue to colourless
increased glucose
concentration?
more glucose
faster respiration
MB decolourise
shorter time
why blue colour returned
after shaking tubes?
oxygen enters solution
MB becomes oxidised
so turns blue