23 October, 2013
- nonpolar AAs are hydrophobic
- Tend to be TM motion.
- 17-20 amino acids to make transmembrane chain – coz of the length of
the fatty acid.
Peripheral membrane protein (not really IMP)
- On surface of membrane
- Do not interact with hydrophobic core. Hydrophilic proteins.
- Made up of mixture of polar and non-polar amino acids. – Coz doesn’t have
exclusively polar amino acids. Non-polar will scattered throughout the
proteins. There are hydrophobic interactions between hydrophobic amino
- Most of these are on cytoplasmic side of a membrane. – Coz they would be
- Hydrophobic nature of a cell membrane restricts free movements of many
molecules and substances which are essential for life
- Movement of a substance across a membrane without need to expand
energy such as ATP.
- Driven by diffusion.
- Diffusion: net movement of a substance from a region of higher to lower
- Primary mechanism of solute movement within the cell and b/w celluer
compartments separated by a membrane.
- Rate of diffusion depends of the concentration gradient.
- Higher the concentration faster the reaction- bigger the gradient, faster
the diffusion rate.
- Form of potential energy.
- Driving force is an increase in entropy.
SIMPLE DIFFUSION :
- Passive transport of substances across lipid portion of membranes with
their concentration gradients - Small and unchar