Intro to Cells

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Intro to Cells
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Introduction to Cells

• Cell- the smallest unit of matter that can carry
  on all life processes

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Discovery of the cell

• English Scientist Robert Hooke- 1665
• Using microscope named cells
• observed remains of dead plant cells
• Anton van Leeuwenhoek- 1673
• First person to observe living cells
• Opened up microscopic world never before seen

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Other important people

• Matthias Schleiden and Theodor Schwann-
• German pair that said the cell is the basic unit
  of function and structure
• Virchow-
• German physician who said all cells come from
  other cells

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Cell Theory

• 1. All living things are composed of cells
• 2. Cells are the basic units of structure and
  function in an organism.
• 3. Cells come from reproduction of existing cells

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Organelles

• Internal structures of cells
• Perform specific functions for the cell
• Organelles maintain the life of the cell
• (just like organs maintain the life of the human)
• Chart in book page 75, table 4.2
• http//gslc.genetics.utah.edu/units/basics/cell
• http//biology.clc.uc.edu/courses/bio104/cells.htm
  

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Lets build a factory . . .
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Factory Scenario

• How are the organelles in the cell like the
  departments in a factory?
• Central office
• Power plant
• Receiving department
• Manufacturing department

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Factory scenario continued

• Warehousing area
• Shipping department
• Waste and recycling system
• Tight security system

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The cells factory-organelles

• Cytoplasm fills cell-contains organelles
• Mitochondria
• Ribosome
• Endoplasmic Reticulum (ER) smooth rough
• Golgi apparatus
• Lysosome

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More organelles

• Cytoskeleton- Microfilaments and microtubules
• Cilia and flagella
• Nucleus
• Cell wall (plant cells)
• Vacuole
• Plastid (plants-ex. Chloroplasts)

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Cell Membrane

• Selectively permeable
• Membrane lipids-hydro-(philic and phobic)
• Peripheral proteins- attached to cell membrane
  (interior and exterior surface)
• Integral proteins- embedded in bilayer
• Fluid mosaic model

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Cell Diversity

• Size-
• limited by surface to volume ratio
• Why?
• Shape- related to cell function
• Internal organization- organelles

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Cell Surface Area

• The outside of a cell is the cell membrane.
• The cell membrane makes up the surface area of
  the cell.
• The white oval line represents the surface area.

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Cell Volume

• All the stuff inside the cell membrane that take
  up space, make up the volume of the cell.
• The blue color represents the volume of the cell.

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Surface to Volume Ratio

• If the volume is 20 units and the surface area is
  5 units, the volume to surface area ratio is
  205.
• If you divide both by the same number, 5, the
  ratio is 41

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Cell Size Limits

• As a cell increases in size the volume to surface
  area ratio decreases.
• As this ratio decreases the ability of the cell
  to function efficiently also decreases.
• This means that cells are limited in size.
• There can never be a 10 foot cell, for example.

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Summary

• The bigger the surface to volume ratio, the
  better off the cell is.
• So a 101 cell is better off than a 31 cell.

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Why are those cells so small?

• Why is it that cells just stayed smaller? How
  come they did not just grow larger?
• Egg Lab
• With a partner pick a hard boiled egg
• Peel away the outer shell
• Cut a small 8x8 mm cube
• Then cut a large 5x5 cm cube out of the egg
• Get two beakers, in both add 150 ml of water with
  10 drops food coloring each
• Add the full (large egg) to one beaker and the
  small cube to the other. Wait ten minutes
• While you are waiting make a prediction as to
  what is going to happen.

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Eukaryotic cell

• Has a NUCLEUS
• Surrounded by nuclear membrane
• Controls most cellular activity (DNA)
• Master plans building-cell proteins, enzymes
• Chromatin, nucleolus, ribosomes
• The organelles in eukaryotes are also surrounded
  by membranes golgi, E.R., lysosome, etc.

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Prokaryotic cell

• Includes bacteria
• Have a cell membrane butits made of different
  chemicals, has a different structure, and may
  sometimes have a cell wall as well.
• Organelles inside not surrounded by a membrane
• No membrane bound Nucleus
• Genetic material may be concentrated in one area
  of the cell, usually in the loop called a plastid.

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Multicellular organization

• Tissues
• Organs
• Organ system
• Evolution of multicellular organisms
• Colonial organisms- ex. Volvox