homeostasis and cell transport -...
TRANSCRIPT
Ch 5: Homeostasis and Cell Transport
Section 1: “Passive Transport”
Section 2: “Active Transport”
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section 1: Fridaysection 2: MondaySection 3: not covered
Cell Membrane
cells maintain homeostasis by controlling the movement of substances across the cell membrane
A lipid bilayer forms the cell membrane
polar head
non-polar tail
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Types of Membrane Proteins
cell-surface markers: name tag for the cell
receptor proteins: enable (=allow) cell to sense surroundings
enzymes: catalyze (=speed up) reactions
transport proteins: help substances move in and out of the cell
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Passive Transportdiffusion: movement of particles from regions of higher density to regions of lower density.
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Osmosis
allows cells to maintain water balance
hypertonic: more solutes in, water will move out
hypotonic: lower solute concentration, water will move in
isotonic: no change in concentration
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Passive Transport
facilitated diffusion: transport proteins help substances diffuse through the cell membrane
channel proteins (pore): serve as a tunnel for substances
carrier proteins: bind to a substance to help it get across the 7
Ch 5: Homeostasis and Cell Transport
Section 1: “Passive Transport”
Section 2: “Active Transport”
8
section 1: Fridaysection 2: MondaySection 3: not covered
Active Transport
requires energy to move substances across concentration gradients
sodium-potassium pump: pumps excess sodium out of cell; osmosis will occur without pump
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