Title: Diffusion and Osmosis: How does stuff get into and out of a cell?
1Diffusion and Osmosis How does stuff get into
and out of a cell?
- The Cell in its Environment
- Ch 7, Section 2
- L3 Biology
2Molecules are always moving
- Molecules move randomly and bump into each other
and other barriers
3Diffusion
- Movement of molecules from an area of high
concentration to an area of lower concentration - Continues until equilibrium is reached.
4Diffusion
5Diffusion
- Occurs without control or energy use it is
called Passive Transport - Affected by
- Size of molecules
- Size of pores in a membrane
- Temperature
- Stirring
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7Simple Diffusion
8Cell Membranes are Semipermeable
- Let some molecules pass through and not others.
- Small molecules pass through ex water
- Large molecules cant pass through ex proteins
and complex carbohydrates
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10Which molecules will diffuse?
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11How long does diffusion continue?
- Until equilibrium is reached
- This means there will be an equal distribution of
molecules throughout the space this is why
odors smell strong at first, then seem to
disappear
12Osmosis A Special kind of Diffusion
- Diffusion of water across a selectively permeable
membrane - Cytoplasm is a solution of water and solutes
(stuff dissolved in the water). - Water moves into and out of cells because of the
different concentrations of the solutes. - Different kinds of cells react differently to
osmosis, depending on the solution they are in
13Blood in different solutions
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15Active Transport uses carrier molecules to move
molecules from an area of lower concentration to
an area of higher concentration
16Endocytosis
- Very large molecules or substances must enter the
cell by the membrane pinching inward
17Pinocytosis
- The cell takes in liquid droplets and forms a
vacuole
18Phagocytosis
- The cell takes in large particles
19Exocytosis
- The cell gets rid of secretions or wastes
20Phagocytosis in action phagocyte (white blood
cell) going after a bacteria cell
The End