Required Practical 4 Flashcards
How do you calculate percentage uncertainties?
percentage uncertainty = uncertainty/mean value x 100%
Which part of the phospholipid is affected if temperature changes?
The fatty acid tails
What happens if the temperature is very high?
- The fatty acid tails gain kinetic energy
- They become less rigid and more fluid
- They gain enough energy to break the hydrogen bonds holding the bilayer together
- Permeability and fluidity of the membrane is increased
- More substances can exit and enter the cell
What happens if the temperature is much too high?
- The integral and peripheral proteins can denature completely
- Membrane becomes so fluid that dangerous substances can exit and enter the cell
What happens if the temperature is very low?
- The fatty acid tails lose kinetic energy
- More rigid and close together
- Less gaps in the bilayer, preventing more substances than usual to enter the cell
- Includes essential substances like oxygen and glucose
What happens if the temperature is much too low?
- The liquid inside the cells can freeze
- Creates crystals that can pierce the membrane and kill the cell
What is the optimum temperature for most cells?
37.5°C
What is a colorimeter?
A light-sensing device that is used to measure the absorbance of light as it moves through a sample of liquid.
Why is red cabbage used in the required practical?
Red cabbage has a red dye inside its cells which will leak out if the cell membrane becomes permeable