2.1.5 Biological Membranes – Factors affecting membrane structure Flashcards
(12 cards)
What effect does lowering temperatures have on molecules?
They have less kinetic energy, causing them to move slower.
When temperature increases, so does membrane _______ and ________.
Permeability
Fluidity
As the temperature begins to increase, what happens to the rate of diffusion across a membrane?
It increases.
Why does diffusion increase across a plasma membrane when the temperature increases?
The phospholipids have more kinetic energy and move more within the bilayer, therefore creating more gaps between the phospholipids, so substances can pass through at a greater rate.
If the temperature is too high, what will happen to the plasma membrane?
The phospholipids will have too much kinetic energy and will break apart from each other. The proteins may also denature.
What two factors affect membrane structure?
Temperature and solvents
What effect do organic solvents have on membranes?
Organic solvents (e.g. acetone/ ethanol) will damage cellular membranes as they dissolve lipids.
In an investigation into the effect of temperature of membrane permeability, what is the independent variable?
The temperature
In an investigation into the effect of temperature of membrane permeability, what is the dependent variable?
The membrane permeability (measured as the absorbance value)
What piece of equipment can be used to measure the opaqueness of a coloured liquid?
A colorimeter
In a scientific experiment, what is the most reliable way to control the temperature of the practical equipment?
Using an electronic water bath
Beetroot cut into cylinders can be used to investigate the effect of temperature on membrane permeability, what must be controlled about the beetroot?
- The species/type
- The age
- Where in the beetroot the samples are taken from (middle/edge etc)
- The length of the beetroot cylinders
- The diameter of the beetroot cylinders
