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1.7 and 1.8 Cells in Their Environment and Osmosis. Text pages 22-28. The Big idea. How do substances move in and ou t of cells. Video . http:// www.youtube.com/watch?v=qotIWgL7zFs. http:// www.youtube.com/watch?v=9QCxTf0QfTo&feature=related. 1.7 Cells in Their Environment. - PowerPoint PPT Presentation
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1.7 and 1.8 Cells in Their Environment
and Osmosis
Text pages 22-28
The Big idea• How do substances move in and out of cells
Videohttp://www.youtube.com/watch?v=qotIWgL7zFs
http://www.youtube.com/watch?v=9QCxTf0QfTo&feature=related
1.7 Cells in Their Environment
• Permeable (all), semi permeable (some) and impermeable (none)
• Cell membrane: – Selectively permeable (pg 22)
• Diffusion– Molecules constantly move and collide, causing
them to spread out– Concentration= the amount of stuff in a specific
area– Molecules always move from an area of high
concentration to an area of low concentration– This is how things move in and out of cells (see
page 24)
1.8 Osmosis (page 25)
• Osmosis:– A type of diffusion involving to water– Water constantly moves in and out of cells
depending on concentration– See page 25 of text
Cells in solutions of different concentrations
• Solute = substance dissolved in another substance
• Solvent= stuff that does the dissolving– E.g., hot chocolate= water (solvent) and chocolate
(solute)• In cells salts and sugars = solutes, and water =
solvent
Examples of Osmosis (see page 26)Example 1: Equal movement of water in and out of cells
Example 2: More water moving into cells than is moving out
Example 3: More water moving out of cells than is moving in
Turgor Pressure
• the main pressure of the cell contents against the cell wall in plant cells.
• cells contain more water in vacuole than flaccid cells (osmotic pressure)
• gives the plant rigidity, and may help to keep it erect. Turgor can result in the bursting of a cell.