hapter 7

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Cell Structure Function
hapter 7
2
Cell Theory

• Contains 3 parts
• All living things are composed of 1 or more cells
• Cells are the basic units of structure function
  in an organism
• Cells come only from the reproduction of existing
  cells

3
Cell Diversity

• Size is dictated by surface to volume ratio
• Surface area 4pr2
• Volume 4/3pr3
• ratio 4pr2 / 4/3pr3
• Shape reflects function nerve cells highly
  branched, skin cells flat, etc.

4
Cell Classification

• Prokaryotic cells
• Comprise 2 kingdoms, Archaebacteria Eubacteria
• Have no membrane bound organelles
• Have no membrane bound nucleus
• Eukaryotic cells
• Comprise 4 kingdoms, Protista, Fungi, Plantae
  Animalia
• Have membrane bound organelles

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The Compound Light Microscope

• Our ocular lens magnifies 10x
• Our objective lens magnify 4x, 10x, 40x
• Magnification ocular x objective
• Condenser iris diaphragm
• How to find something
• Locate center under low power focus 1st using
  coarse adjustment
• Rotate nosepiece to next objective, use FINE
  adjustment ONLY
• NEVER USE COARSE WHEN USING HIGH POWER

6
Concentration Gradient Diffusion

• Like water flowing down a hill, a high
  concentration of gas molecules or dissolved
  molecules will flow to a lower concentration

Over time, the concentrated molecules equally
distribute themselves through a natural process
called diffusion.
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Passive TransportMovement across cell membrane
w/o use of energy

• Solvent liquid in which particles are dissolved
• Solute particles dissolved in solvent
• Diffusion
• Movement of molecules from a position of high
  conc. to low conc.
• Occurs until at equilibrium

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Diffusion across a Cell Membrane

• Permeable membrane one that allows particles to
  pass through it
• Selectively permeable membrane allows only
  certain particles to pass through it
• Could be liquids or gases

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Osmosis diffusion that refers to water only

• Hypertonic more solutes outside cell than
  inside cell, cell shrinks as it loses water,
  called plasmolysis
• Hypotonic more solutes inside cell than
  outside, water flows into cell
• Cytolysis animal cells swell until they burst
• Plants swell but not burst, become turgid
• Isotonic solutes inside outside

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12
Homeostasis

• The maintenance of a stable environment
  regardless of external environment, i.e. your
  body temperature

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Facilitated Transport

• Passive transport utilizing a carrier protein
  that creates a channel across membrane
• Particles still move with conc. gradient, always
  high to low conc.
• Carrier proteins assist those particles that
  cannot get across fast enough to keep up with
  demand
• Ion channels allow ions to flow freely

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Active Transport

• To maintain homeostasis items may need to flow
  against the conc. gradient or large quantities
  are needed at once. ENERGY MUST BE UTILIZED!
• Pinocytosis is movement of liquids in and out of
  cell.
• Phagocytosis is movement of large particles or a
  whole bacterial cell.

Endocytosis into cell Exocytosis out of cell