unit 3 pp #9
TRANSCRIPT
Cellular Transport
Energy-less Transport
1) Diffusion – movement of substances from a higher concentration to lower concentration– The unequal distribution of particles is called
a concentration gradient– GOAL: EQUAL CONCENTRATION ON BOTH
SIDES– Osmosis: movement of water
Types of SolutionsInside Cell Outside Cell Movement
Isotonic Solution Concentration inside and outside of the cell is equal
Movement of material inside and outside of the cell is equal
Hypotonic Solution
More dissolved substances in the cell
More water outside the cell
Movement of water inside the cell (cell swells)
Hypertonic Solution
More water inside the cell
More dissolved substances outside the cell
Movement of water outside of the cell (cell shrinks)
Hypertonic Solution
Hypotonic Solution
Isotonic Solution
Energy-less Transport Con’t.
2) Passive Transport – movement of particles across the cell membrane
a) Proteins – special proteins (transport proteins) help larger substances move through the membrane
- Channel Proteins – aqueous channel that allows soluble material to pass into and out
of the cell - called facilitated diffusion - driven by the concentration gradient - transport sugars and amino acids
Active and Passive Transport
Active Transport
• Requires energy
• Materials move against a concentration gradient
• Acts against diffusion
• Includes use of transport proteins
• Includes exocytosis and endocytosis
How does active transport work?
1. A carrier protein binds with a particle of the substance to be carried across the membrane
1. Moves the substance across based on charge and concentration (electrochemical gradient)
2. When bonding has occurred, the chemical energy changes the shape of the carrier protein so that the particle is released into the cell
3. Once released, the carrier protein regains its original shape
Active Transport
Gated Channels
• Involved in active transport
• Form a “gate” over certain pores.
• They are stimulated to open by a “ligand”, allowing substances to pass through.
Endo- and Exo- cytosis
• Endo – in• Cell surrounds and
takes in material from the environment
• Creates a vacuole– Vacuole is called a
coated vesicle
• Exo – out• Expulsion or excretion
of wastes, secretion of hormones
Endocytosis
Exocytosis