Structure and Function of Organelles cell (plasma) membrane semi-permeable membrane which regulates the passage of substances into and out of the cell semi-permeable membrane which regulates the passage of substances into and out of the cell composition: protein molecules dispersed throughout a double layer of lipid (fluid mosaic) composition: protein molecules dispersed throughout a double layer of lipid (fluid mosaic)

Animal Cell Plant Cell Eukaryotic Cell

Factors affecting permeability of cell membrane to a particular substance: 1. molecular size of the substance: cell membrane generally is permeable to small molecules such as water (H 2 O), carbon dioxide (CO 2 ), glucose (C 6 H 12 O 6 ) and amino acids 1. molecular size of the substance: cell membrane generally is permeable to small molecules such as water (H 2 O), carbon dioxide (CO 2 ), glucose (C 6 H 12 O 6 ) and amino acids

Factors affecting permeability of cell membrane to a particular substance: 1. molecular size of the substance 1. molecular size of the substance 2. electrical charge on the atom or molecule of the substance 2. electrical charge on the atom or molecule of the substance Na + Cl -

Factors affecting permeability of cell membrane to a particular substance: 1. molecular size of the substance 1. molecular size of the substance 2. electrical charge on the atom or molecule of the substance 2. electrical charge on the atom or molecule of the substance 3. solubility of the substance in water 3. solubility of the substance in water

Factors affecting permeability of cell membrane to a particular substance: 1. molecular size of the substance 1. molecular size of the substance 2. electrical charge on the atom or molecule of the substance 2. electrical charge on the atom or molecule of the substance 3. solubility of the substance in water 3. solubility of the substance in water 4. solubility of the substance in lipid 4. solubility of the substance in lipid

What determines the direction of the movement of molecules (diffusion) across the cell membrane? concentration of substances on each side of the membrane concentration of substances on each side of the membrane Diffusion is a form of passive transport. (no energy required) Click on image for movie.

Osmosis diffusion of water through a semi- permeable membrane from an area where the water molecules are more concentrated to an area where the water molecules are less concentrated diffusion of water through a semi- permeable membrane from an area where the water molecules are more concentrated to an area where the water molecules are less concentrated

Cells exposed to an isotonic solution will neither lose nor gain water exposed to an isotonic solution will neither lose nor gain water exposed to a hypotonic solution will swell due to the uptake of water by the cell exposed to a hypotonic solution will swell due to the uptake of water by the cell exposed to a hypertonic solution will shrink due to the loss of water from the cell exposed to a hypertonic solution will shrink due to the loss of water from the cell

Active transport requires energy. A transport protein actively pumps a specific solute across a membrane against the solute’s concentration gradient; i.e., away from where the solute is less concentrated. Membrane proteins use ATP as their energy source for active transport. A transport protein actively pumps a specific solute across a membrane against the solute’s concentration gradient; i.e., away from where the solute is less concentrated. Membrane proteins use ATP as their energy source for active transport.

energy