Bio – week 5 – lecture 1 – 31/3/25 – Osmosis
Centrosomes = Chromosomes can be attached by their
centromeres to structures called centrosomes.
Terminology:
If a solute can pass through a membrane, we say…
- The membrane is permeable to the solute
- The solute is permeant to the membrane.
Moles and molarity:
A “mole” of particles is about 600,000,000,000,000,000,000,000 particles or 6x10^23
particles
- We use moles for comparing concentrations. 6 x 10^23 glucose molecules in a Litre
of solution is a 1 mol/L glucose solution.
- Mol/L is pronounced “moles per litre” but we can also say “Molar” abbreviated “M”.
- Concentration is sometimes called “molarity”
- In biology, we’re normally interested in lower concentrations, so we use mmol/L (or
mM), umol/L (or uM), and nmol/L (or nM = 1 billion of a litre).
Moles and osmoles:
How to work out osmosis question:
Think about solutes first. Are any dissociative? Are any permeant (usually gases and small
uncharged molecules)? Remember that permanent solutions will move according to their
ow concentration gradients
- Remember water will move towards the higher total solute concentration
(osmolarity).
Hypertonic solution = solution has a higher solute concentration than cell -> water moves
out of cell.
Isotonic solution = concentration of solutes inside the cell is same as concentration outside -
> no net movement of water in or out which is an isotonic solution.
Hypotonic solution = solution lower solute concentration than cell -> water moves into cell.
Centrosomes = Chromosomes can be attached by their
centromeres to structures called centrosomes.
Terminology:
If a solute can pass through a membrane, we say…
- The membrane is permeable to the solute
- The solute is permeant to the membrane.
Moles and molarity:
A “mole” of particles is about 600,000,000,000,000,000,000,000 particles or 6x10^23
particles
- We use moles for comparing concentrations. 6 x 10^23 glucose molecules in a Litre
of solution is a 1 mol/L glucose solution.
- Mol/L is pronounced “moles per litre” but we can also say “Molar” abbreviated “M”.
- Concentration is sometimes called “molarity”
- In biology, we’re normally interested in lower concentrations, so we use mmol/L (or
mM), umol/L (or uM), and nmol/L (or nM = 1 billion of a litre).
Moles and osmoles:
How to work out osmosis question:
Think about solutes first. Are any dissociative? Are any permeant (usually gases and small
uncharged molecules)? Remember that permanent solutions will move according to their
ow concentration gradients
- Remember water will move towards the higher total solute concentration
(osmolarity).
Hypertonic solution = solution has a higher solute concentration than cell -> water moves
out of cell.
Isotonic solution = concentration of solutes inside the cell is same as concentration outside -
> no net movement of water in or out which is an isotonic solution.
Hypotonic solution = solution lower solute concentration than cell -> water moves into cell.
