Transport Through Membranes. I.Plasma membrane A.Flexible boundary between cell and its environment....
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Transcript of Transport Through Membranes. I.Plasma membrane A.Flexible boundary between cell and its environment....
Transport Through
Membranes
I. Plasma membrane
A. Flexible boundary between cell and its environment.
B. Selective Permeability – allows certain molecules to pass through while keeping others out.
C. Phospholipid Bilayer
1. Glycerol backbone.
2. Two fatty acid chains.
3. Phosphate group.
4. Two phospholipid layers.
II. Types of transport
A. Passive transport.
1. Requires no energy, as in
a.Simple diffusion
b.Facilitated diffusion
c.Osmosis
2. Moves materials
a.From higher concentrations
b.To lower concentrations
3. Solutions.
a.Hypertonic
1)Has higher concentration of salt, sugar, etc.
2)Causes cells to release water (lose mass).
b.Hypotonic
1)Has lower concentration of salt, sugar, etc.
2)Causes cells to absorb water (gain mass).
c. Isotonic
1)Has same concentration of salt, sugar, etc.
2)Cells balance absorbing and releasing water (same mass).
Hypotonic Hypertonic Isotonic
or or or
Hypertonic or Hypotonic or Isotonic?
Hypertonic or Hypotonic or Isotonic?
Hypertonic or Hypotonic or Isotonic?
Hypertonic or Hypotonic or Isotonic?
III. Active transport.
A. Requires
1. Energy
2. Transport Proteins
B. Moves materials
1. From lower concentrations
2. To higher concentrations
IV.Proteins - involved in both passive diffusion and active diffusion.
A.Protein channels create “tunnels” that don’t require energy. (left picture)
B.Carrier proteins require energy. (right picture)
V. Endocytosis – large materials into cell
VI. Exocytosis – wastes expelled