Cell Organelles and Processes

Cell Wall Is found in plant or fungus cell , not animal Outer layer Made of cellulose Supports and protects cell Allows H2O, O2, CO2 to pass into and out of cell

Cell Membrane Found in both plant and animal cells Plant - inside cell wall Animal - outer layer Selectively permeable (filter) Controls movement of materials in/out of cell

Nucleus Found in all cells Large, oval Controls all cell activities Contains DNA

Cytoplasm Found in all cells Clear, thick, jellylike material Supports /protects cell organelles

Mitochondria In all cells Bean-shaped with inner membranes Breaks down sugar molecules into energy –Called “Power Plants” of the cell

Chloroplasts Found in plant, not animal cells Green, oval containing chlorophyll (green pigment) Uses energy from sun to make food for the plant (photosynthesis)

Vacuole Plant - large Animal - small Fluid-filled sacs Store food, water, waste (plants need to store large amounts of food)

Plant or Animal? Plant and animal cells are similar in structure but there are differences. This is an illustration of a plant cell and animal cell

Plant cells have a cell wall, animal cells do not. Plant cells have chloroplasts, animal cells do not. Plant cells generally have a more rectangular shape because the cell wall is more rigid. Animal cells have a round or irregular shape because they do not have a cell wall. Both plant and animal cells contain a cell membrane.

Comparing a Cell to a Factory Turn your books to Page 20 (Book C)

End of Cell Structure Notes

Diffusion and Osmosis Diffusion - the process by which molecules spread from areas of high concentration, to areas of low concentration. When the molecules are even throughout a space - it is called EQUILIBRIUM

Osmosis - the diffusion of water (across a membrane) Like other molecules water will move until it’s evenly spread on both sides of the membrane. For example: salt is a solute, when it is concentrated inside or outside the cell, it will draw the water in its direction. This is also why you get thirsty after eating something salty.

Suppose an animal or a plant cell is placed in a solution of sugar or salt in water. If the medium is hypotonic — a dilute solution, with a higher water concentration than the cell — the cell will gain water through osmosis. If the medium is isotonic — a solution with exactly the same water concentration as the cell — there will be no net movement of water across the cell membrane. If the medium is hypertonic — a concentrated solution, with a lower water concentration than the cell — the cell will lose water by osmosis. So basically, if a cell is put in a solution which is more concentrated than its own, then it will shrivel up, and if it is put in a solution less concentrated than its own, the cell will expand and burst.