PAG - The effect of ethanol concentration on membrane permeability Flashcards
1
Q
Background -
A
- Cell surface membrane has selectively permeable phospholipid bilayer
2
Q
what is membrane permeability affected by -
A
- temperature
- concentration of solvents
3
Q
The higher concentration of membrane permeability, what will happen to the beetroot
A
more belatain pigment will leak out of cells
4
Q
Step 1-
A
- Label 6 test tubes with concentrations of ethanol - 0%, 20%, 40%, 60%, 80%, 100%
- complete a table to work out the ratio of ethanol concentration : volume of water we need so each test tube has 5cm3 volume
= simple dilution
5
Q
after the simple dilution what is next
A
- collect beetroot cylinders and cut using a cork borer
- trim to 5mm each using a knife and ruler on a white tile
- rinse the cylinders and pat dry using a paper towel
6
Q
after we have prepared our cylinders what do we do
A
- add 1 cylinder to each test tube and leave for 15 minutes
- label cuvette tray with ethanol concentrations
- swirl the test tubes once after 15 minutes and use forceps to remove the cylinders
7
Q
after the cylinders have been removed what do we do (colorimeter)
A
- pour the liquids into the corresponding cuvettes
- have a blank cuvette with water to act as a blank and a control
- use a colorimeter to measure absorbance
8
Q
what filter is the colorimeter set at
A
green - 520 nm
9
Q
what is absorbance measured in
A
arbitary units - au
10
Q
what do we do once our data has been collected
A
plot a graph
11
Q
conclusion
A
the greater liquid, the more the phospholipid bilayer has been dissolved and membrane has been disrupted allowing more pigment to leak out
12
Q
IV
A
ethanol concentration
13
Q
DV
A
absorbance
14
Q
CVs
A
- ensure all beetroot cylinders are cut to 5mm
- add each cylinder to test tube for 15 minutes, the same time
- make sure each absorbance was read with the green filter at 520 nm
