Biology Chapter 5 Lecture Notes Homeostasis and Transport · Biology Chapter 5 Lecture Notes Homeostasis and Transport 5-1 I) Passive Transport is the movement of substances across

Biology Chapter 5 Lecture Notes

Homeostasis and Transport

5-1

I) Passive Transport is the movement of substances across a membrane without energy input by the cell.

II) Diffusion - is the net movement of molecules from an area of high concentration to an area of low

concentration.

A) Diffusion uses the Concentration Gradient.

1) Concentration Gradient is the difference between the concentration of a particular molecule

in one area and its concentration in an adjacent area

B) Diffusion is driven by the Kinetic Energy of the Molecules.

C) Diffusion depends on the temperature and the size of the object that is diffusing.

D) Equilibrium is when the concentration of molecules is the same throughout.

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III) Osmosis - diffusion of H20 across a semi-permeable membrane

A) Water also moves from a high concentration to a low concentration

B) Semi-Permeable Membrane - allows only certain  molecules to pass through it

C) Hypertonic, Hypotonic and Isotonic Solutions

1) Hypertonic Solution - the concentration of solutes outside cell is higher than the

concentration of solutes inside cell.

a) H20 diffuses outside of the cell

b) Often cells will shrivel up and die

2) Hypotonic Solution - the concentration of solutes outside the cell is lower than the

concentration of solutes inside the cell.

a) H20 flows into the cell

b) Often cells will burst and die

3) Isotonic Solution - the concentration of solutes outside the cell equates the

concentration of solutes inside the cell.

IV) Facilitated Diffusion - is the use of carrier proteins for diffusion that requires no energy.

A) It is a form of passive transport and cost the cell no energy.

1) Carrier Proteins change shape when attached to

and carry a molecule across the membrane.

B) Goes with the concentration gradient

C) Molecules bind to carrier proteins.

VI) Active Transport - when energy is used to transport molecules across the membrane.

A) Cell Membrane Pumps are used to move molecules against the concentration gradient (from

low to high).

1) Since it takes energy it usually moves one type of molecule in and a different molecule out

Ex: plant's roots.

V) Ion Channels- provides passageway across a membrane for specific ions (Na+, K+, CL-)

A) Some are always open and some open and close.

B) Some channels take energy and some do not.

Facilitated Diffusion  Active Transport

VII) Bulk Transport - large molecules, food & other substances are packaged in membrane bound sacs

and moved across the cell membrane.

A) Endocytosis is the process by which cells ingest large molecules.

1) Pinocytosis – Moving in of cell fluids (cell drinking)

2) Phagocytosis – Movement in of large particles or whole cells.

B) Exocytosis is the release of substances from cell to environment.

Attachments

Diffusion - YouTube.flv

water food coloring - YouTube.mp4

Diffusion Osmosis - YouTube.flv

Osmosis demonstration with a raw egg - YouTube.flv

Passive Active Transport - YouTube.flv

active transport.wmv - YouTube.flv

Endocytosis Exocytosis - YouTube.flv

White Blood Cell Chases Bacteria - YouTube.flv