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Homeostasis and Cell TransportChapter 5

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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”

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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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Vesicles

endocytosis: movement of large substances into a cell using a vesicle

exocytosis: movement of large substances out of a cell using a vesicle

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