Cell Processes

1
Cell Processes

• Passive Transport - The movement of substances
  across a cell membrane without the cell using
  energy

• ex diffusion, osmosis, facilitated diffusion

2
Diffusion

• the movement of molecules from an area of higher
  concentration to an area of lower concentration.
  Occurs using the kinetic energy of the molecules.
  

http//www.scivit.de/glossar/biochemie/diffusion.g
if
3

• Molecules will change direction when they hit
  other particles or if there are no particles in
  the way, they will move to less concentrated
  areas.

http//www.scivit.de/glossar/biochemie/diffusion.g
if
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Concentration gradient

• the difference in concentration of a substance
  across space

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Equilibrium

• when the concentration of the molecules of a
  substance is the same throughout an area state
  in which no net change occurs even though there
  is random movement of molecules

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• Ability for molecule to diffuse across cell
  membrane depends on
• 1. Size of molecule
• 2. Type of molecule
• 3. Chemical nature of molecule

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Facilitated diffusion -

• diffusion of materials across a cell membrane
  assisted by carrier molecules

8
Osmosis

• The diffusion of water across a selectively
  permeable membrane water moving from an area of
  greater concentration to a lower concentration
  across a selectively permeable membrane

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Isotonic solution

• a solution whose solute concentration and water
  concentration equals that inside a cell

10
Hypotonic Solution

• a solution whose solute concentration is lower
  than that inside a cell and the water
  concentration is greater outside the cell

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• water will move into the cell if it is placed in
  a hypotonic solution think hippo fat
• a fat cell - cell will swell in hypotonic
  solution

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Hypertonic Solution

• a solution whose solute concentration is higher
  and water concentration is lower than that inside
  a cell water will move out of the cell if it
  placed in a hypertonic solution

13
How Cells Deal with Osmosis

• When in a hypotonic solution, some cells will
  pump out solutes so that water is less likely to
  move into the cell

14
Active Transport

• Energy-requiring process that moves material
  across a cell membrane against a concentration
  difference

15
Contractile vacuole

• structure in unicellular organisms (protists)
  that removes excess water by contracting
  requires the cell to use energy

16
Osmosis -

• diffusion of water molecules through a
  selectively permeable membrane from an area of
  higher concentration to an area of lower water
  concentration.

17
Selectively permeable -

• when a biological membrane allows some substances
  to pass through but not others

18
http//academic.brooklyn.cuny.edu/biology/bio4fv/p
age/osmofr.htm
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Active transport -

• energy-requiring process that moves material
  across a cell membrane against a concentration
  difference

20

• ex Membrane- associated pumps - special
  transport macromolecules in cell membrane move
  calcium, potassium, and sodium

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Endocytosis -

• materials are taken into the cell through
  movements of the cell membrane by means of
  forming pockets or infoldings of cell membrane

22
Phagocytosis

• when large particles are taken into the cell by
  endocytosis

http//
http//gak.med.kagawa-u.ac.jp/daigin/eng_info/His
ology__Cell_Biology/PIC2.jpg
http//pages.britishlibrary.net/nick.lane/images/P
hagocytosis.jpg
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Pinocytosis -

• cell takes in small droplets of liquids by
  forming tiny pockets along cell membrane

http//www.bom.hik.se/bio710/mixo/img4.jpg
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Exocytosis -

• when large molecules are removed from the cell.
  The membrane surrounding the material fuses with
  the cell membrane, forcing the material out of
  the cell.