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 FactoryTurn 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.