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Lecture 6

BIOL107 Lecture 6: BIO107 – Lecture 6-Cell Transport, Cytotic Transport


Department
Biology (Biological Sciences)
Course Code
BIOL107
Professor
Cirelli,Damián
Lecture
6

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BIO107 Lecture 6- Cell Transport, Cytotic Transport
Cell Transport Recap:
Diffusion: movement of a solute from an area of high concentration to an area of low
concentration.
Things cannot diffuse from an area of low concentration to an area of high concentration;
cannot go against the concentration gradient.
Water can diffuse through a membrane but it is very inefficient.
Osmosis: High energy water moves toward low energy water.
How do Solutes get Across the Plasma Membrane?
Figure 1.Types of transport across membranes.
Passive Channels
Passive and Active Transporters
Diffusion
Transport Through the Membrane: Simple Diffusion
Diffusion through the phospholipid bilayer:
Gases
“Small” non-polar substances
Examples: Carbon Dioxide (CO2), Oxygen (O2), Steroid Hormones
It is possible for water to diffuse through the membrane, but it is very inefficient.
Transport through the membrane: Passive Transport- Channels
Channels provide facilitated diffusion (a structure that facilitates/ helps the process of
diffusion) of ions and water without requiring energy.
Channels facilitate the diffusion of molecules from one side of the membrane to the
other.
Since these channels are passive they do not require energy, and generally remain the
same shape.
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