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ICT IN BIOLOGY
MEMBRANE INTEGRITY IN RED CABBAGE LEAF
CELLS
Red
cabbage leaf epidermal cells are pigmented purple
with anthocyanins. The pigments are held in their
sap vacuoles. If the membranes of the cell are
damaged these pigments will leak from the cell.
Heat will
denature proteins, including those in the cell
membranes. At what temperature do red cabbage cell
membranes breakdown?
MATERIALS
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TI Graphing Calculator with
DataMate program installed
CBL2 interface
Colorimeter sensor
10 cuvettes
Electronic water bath
Thermometer |
10 test
tubes in a rack
1cm diameter cork borer
red cabbage
10cm3 syringe
Marker pen
Pipette |
METHOD
-
Cut discs from the red cabbage and
select 30 which are of uniform thickness. Place three
discs in each test tube and add 10cm3 of distilled
water to each tube.
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Put the tubes in the water bath
and set the temperature to 40°C. When the temperature
reaches 40°C remove a tube. Continue raising the
temperature and remove a tube at 5°C intervals.
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Suck up liquid from a test tube
and fill a colorimeter cuvette until it is 1 cm from
the top. Wash the pipette, take a sample from the
next tube and fill a fresh cuvette. When labelling
the cuvettes mark one side only near the top. Handle
the cuvettes near the top too.
Starting the DataMate Program and calibrating the
sensor
-
Use the
following steps to start the DataMate program on your
calculator:
Press
(for TI-73, 82 and 83 press
),
then press the calculator key for the number that
precedes
DATAMATE.
Press
.
An introductory screen will appear, followed by the
main screen.
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Plug the colorimeter probe into
channel
CH 1
on the CBL2 interface.
Collecting data
Trouble shooting
If you get readings that appear strange or impossible
try the following:
(a)
Press
and reboot the Datamate program.
(b)
Check the liquid that you have sampled. Is it
homogeneous?
(c)
Check the cuvette that you are using is not dirty or wet
on the outside.
(d)
Check the cuvette holder in the colorimeter. Is it clean
and dry?
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Note: You should try to keep your results between 0.050
– 0.550 absorbance. Outside this range the
calibration curve is not linear. If your results
are outside this range try a different wavelength
(light source) or the liquid may need diluting by
a known factor. |
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MOST IMPORTANT Storing your data in the
calculator’s archive
If you do not do this your data will be
lost. The next time you use a
spread sheet the data in L1, L2
etc will get compressed.
Archiving data will remove it from the RAM
memory but it will not stop it from being
over-written when new data is recorded. It
needs to be renamed.
To archive or unarchive a list variable
(L1) using a Memory Management editor
This frees up RAM memory so that you can continue recording more data.
1.
Press
then
MEM to display the MEMORY
menu.
2.
Select 2:Mem Mgmt/Del... to display the MEMORY
MANAGEMENT/DELETE menu.
3.
Select 4:List... to display the LIST menu.
4.
Press to archive L1. An asterisk (*) will appear to the
left of L1 to indicate it is an
archived variable.
To unarchive a variable in this screen, put
the cursor next to the archived variable
and press
. The asterisk will disappear.
5.
Press
then
QUIT to leave the LIST
menu. |
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ICT in Biology
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This Site was last
updated on
29/10/07
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© Paul Billiet 2007 |