Title: Biological Membranes
1Biological Membranes
- Formation of the membrane lead to appearance of
the first cell. - Membrane define boundaries of the cell.
- Regulate traffic in and out of the cell.
- Divide internal space into compartments.
- Segregate processes and reactions.
2Biological functions of membranes are derived
from their physical properties.
- Flexible (allow cell growth and movement).
- Self-sealing (allow endo- and exo-cytosis).
- Selectively permeable to polar solutes (can
retain selectively specific compounds with in
cells). - Membranes contain proteins which catalyze various
cellular processes.
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4Membrane architecture.
- Membrane consist of two layers.
- Membranes are two-dimensional.
- Membranes are fluid.
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6Lipid composition of different membranes of the
rat hepatocyte.
7Fluid mosaic model
8Structural elements of membranes.
9Asymmetric distribution between inner and outer
monolayer.
10Membranes in motion.
11Organisms adapt their membranes to suit their
needs.
12Membrane proteins diffuse freely in the bilayer.
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14Some proteins span the lipid bilayer.
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16Proteins that span the bilayer.
17Peripheral and integral proteins.
18Proteins can be covalently attached to the lipids.
19Classification of the integral membrane proteins.
20Sequence of proteins can give clues to their
location.
21Membrane fusion.
22Viral entry through membrane fusion.
23Transport across membranes.
- Simple diffusion. Higher concentration to lower
concentration. - Ions of opposite charge separated by membrane,
create electrical gradient, Vm. - Direction of movement depends on the chemical and
electrical gradient. - Electrochemical gradient of electrochemical
potential.
24Solute transport across membranes.
25Transmembrane passage.
- Facilitated diffusion or passive transport.
- Transporters and permeases catalyze transport.
26Glucose transporter (passive).
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