Bio – week 4 – lecture 2 – 28/3/25 -> membrane transport:
Centromeres: in eukaryotes after DNA replication, pairs of DNA
molecules are held together at regions called centromeres.
Simple diffusion: hydrophobic molecules and (at slow
rate) very small uncharged polar molecules can diffuse
through the lipid bilayer.
Good for:
- Dissolved gases (O2 and CO2)
- Other small uncharged molecules (H2O)
- Hydrophobic molecules (some lipids such as
steroid hormones)
Facilitated diffusion: many hydrophilic substances
diffuse through membranes with assistance from
transport proteins -> either channel proteins or carrier
proteins.
Good for:
- Anything charged (ions, amino acids)
- Larger hydrophilic molecules such as sugars.
Both high concentration -> low concentration.
Simple diffusion kinetics:
- In simple diffusion, the rate
of diffusion is proportional to
the concentration gradient.
Higher concentration
gradient -> faster diffusion
Centromeres: in eukaryotes after DNA replication, pairs of DNA
molecules are held together at regions called centromeres.
Simple diffusion: hydrophobic molecules and (at slow
rate) very small uncharged polar molecules can diffuse
through the lipid bilayer.
Good for:
- Dissolved gases (O2 and CO2)
- Other small uncharged molecules (H2O)
- Hydrophobic molecules (some lipids such as
steroid hormones)
Facilitated diffusion: many hydrophilic substances
diffuse through membranes with assistance from
transport proteins -> either channel proteins or carrier
proteins.
Good for:
- Anything charged (ions, amino acids)
- Larger hydrophilic molecules such as sugars.
Both high concentration -> low concentration.
Simple diffusion kinetics:
- In simple diffusion, the rate
of diffusion is proportional to
the concentration gradient.
Higher concentration
gradient -> faster diffusion
