Chapter 7 Notes

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Chapter 7 Notes

• Cell Structure and Function

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Cells and Cell Theory

• Cell the basic unit of all forms of
  life
• History
• Robert Hooke (1665)
• - described the empty chambers of cork as
  cells

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• 2. Matthias Schleiden (1838)
• - all plants are made of cells
• 3. Theodor Schwann (1839)
• - all animals are made of cells
• 4. Rudolph Virchow (1855)
• - all cells come from
  preexisting cells
• before this, people believed
  in spontaneous generation

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• Cell Theory
• 1. All living things are composed of 1 or
  more cells
• 2. Cells are the basic units of life
• 3. All cells come from preexisting cells
• exception viruses?

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II. Prokaryotes and Eukaryotes

• Prokaryotic cells do not have nuclei
• - example all bacteria
• Eukaryotic cells have nuclei and organelles
• - example plants, animals, fungi

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III. Cell Structures

• Cytoplasm everything between the membrane and
  nucleus
• 1. Structure
• a. Cytosol jelly-like mixture
  consisting of water, proteins,
  carbohydrates, and other organic compounds

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• b. Organelles structures that work
  like miniature organs, carrying out
  specific functions in the cell
  (suspended in the cytosol)
• 2. Function
• a. Biological reactions take place in the
  cytosol
• b. Organelles each have specific jobs
  within the cell

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• 3. Analogy
• - like the body of a person
• organelles organs
• cytosol everything surrounding organs

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IV. Cell Shape and Size

• Maintenance of shape
• 1. In plants cell wall
• 2. In animals cytoskeleton
• Cytoskeleton
• - consists of 2 types of structures
• 1. Microtubules hollow tubes made of
  tubulin

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• a. Cilia short, hair-like projections
• b. Flagella long, whip-like projections

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• 2. Microfilaments NOT hollow 2
  twisted chains of proteins (like a rope)
• Size of Cells
• - can vary from 1 micrometer (bacteria) to 1
  meter (nerve cell)

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Movement through the Membrane

• The cell membrane is semipermeable
• - only certain molecules can get through
• Passive transport no energy required
• 1. Diffusion the movement of
  molecules from a region of high
  concentration to a region of low
  concentration

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• - continues until equilibrium is reached (equal
  concentrations on both sides of membrane)

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• - temperature affects diffusion
• higher faster
• - size of particles affects diffusion
• smaller faster

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• 2. Osmosis the diffusion of water across a
  membrane from high water concentration to low
  water concentration

Which way will the water move?
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• Which way will the water move?

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• This solution is hypertonic
• - water diffuses out of the cell

This solution is hypotonic

• - water diffuses
• into the cell

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• This solution is isotonic
• - no net change

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• 3. Facilitated diffusion uses protein
  channels to move molecules from high
  concentration to low concentration
• Active Transport energy required
• 1. Carrier proteins may act as pumps
• -example sodium-potassium pump
• a. Cells continually pump potassium
  ions into the cell, and sodium ions out

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• Important for muscle contraction and nerve
  impulse transmission

Na
K
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• 2. Endocytosis materials move into cell

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• a. Pinocytosis membrane encloses a
  fluid droplet and brings it inside the cell
• b. Phagocytosis membrane encloses a
  large particle and brings it inside the
  cell

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• 3. Exocytosis materials move outside the cell
• - wastes and cell products may leave the
  cell this way