Biology 11 - Introduction to Biology

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Introduction to Biology
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Welcome to Biology

• Biology a science, specifically the studying of
  living things
• Modern biology is grounded in the study of
• Cell Theory
• Genetics (gene theory)
• Energy
• Homeostasis
• Evolution

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What makes something alive?

• The following are characteristics of living
  things
• Maintain homeostasis a steady internal state

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What makes something alive?

• Have the ability to reproduce

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What makes something alive?

• Have metabolism

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What makes something alive?

• Have some sort of cellular organization /
  function
• Contain genetic information

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What makes something alive?

• The following are characteristics of living
  things
• Maintain homeostasis a steady internal state
• Have the ability to reproduce
• Have some sort of cellular organization /
  function
• Have metabolism use chemical energy to survive
• Contain genetic information

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What makes something alive?

• The following are characteristics of living
  things
• Maintain homeostasis a steady internal state
• Have the ability to reproduce
• Have some sort of cellular organization /
  function
• Have metabolism use chemical energy to survive
• Contain genetic information

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Interesting Facts about Cells

• The average human being is composed of around 100
  Trillion individual cells!!!
• It would take as many as 50 cells to cover the
  area of a dot on the letter i
• People did not always know about cells.

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DISCOVERING CELLS
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Microscopes

• Cells are tiny, not discovered until the
  invention of the microscope
• Microscopes magnify an object
• Magnification
• Means making objects appear larger than they are
• Example Magnifying class

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Magnification
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Microscopes

• Resolution
• How clearly an image appears
• High Resolution clear image, lots of detail
• Low Resolution blurry image, less detail

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Resolution
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Resolution
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Resolution
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Resolving Power

• The ability to distinguish between two dots or
  objects that are very close together is called
  resolving power.
• The human eye has a certain resolving power. You
  can see the individual dots in diagrams A, B and
  C. The human eye does not have the resolving
  power to see the dots in diagram D.

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Robert Hooke

• Invents a single-lens microscope and observes the
  world around him (late 1600s)
• Records observations in his book Micrographia
  (1665)

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Hookes Mircoscope
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Hookes Microscope
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Hookes Drawings
More to the world than meets the eye
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Hookes Drawings
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Hookes Drawings

• Long-legged spider

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Robert Hooke

• Discovers Cells (1665)
• Observes bark of a cork tree
• Observes tiny honey comb structures, which he
  calls cells
• Problem
• Cork bark cells are dead
• Thought only plants had cells

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Cork Bark Cells
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Anton van Leuwenhoek

• Makes observations at same time as Hooke
• Improves the Microscope
• Grinds the lens of the microscope to the size of
  a pin head
• Improves magnification to 350x

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AVLs microscope
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Anton van Leuwenhoek

• Observes (1) rain pond water, and (2) blood
• Animacules
• Observed living cells in water
• These were bacteria cells
• Blood Cells
• Observes different types of cells in blood

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Life in Water
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Life in Water
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Cells in Human Blood
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Spontaneous Generation

• Few discoveries about cells from 1650 to 1850.
  But why?
• People believe in Spontaneous Generation
• The belief that life simply starts
• Maggots come from rotting meat
• Mice come from dirty clothes and corn

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MODERN CELL THEORY
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Spontaneous Generation Disproved

• Francesco Redi
• Italian physician poet
• One of the first scientists to disprove
  spontaneous generation
• Performs famous experiment in 1668

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Spontaneous Generation Disproved
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Cell Theory (classical)

• 3 major laws
• All organisms are made of one or more cells.
  (Schleiden Schwann)(1838-39)
• The cell is the basic unit of life in all living
  things. (Schleiden Schwann)(1838-39)
• All cells come from other (preexisting) cells.
  (Virchow)(1858)

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Cell Theory (modern)

• Modern cell theory adds 4 more statements
• The cell contains hereditary information(DNA)
  which is passed on from cell to cell during cell
  division.
• All cells are basically the same in chemical
  composition and metabolic activities.
• All basic chemical physiological functions take
  place in the cell
• Cell activity depends on the activities of
  structures within the cell (organelles, nucleus,
  plasma membrane

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Cell Specialization

• Some cells are part of a larger organism
• These cells must become specialized and perform
  specific jobs
• Cell Specialization
• When cells perform a specific function as part of
  a larger organism
• To perform this job, cells often become
  specialized (look work differently)

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Examples of Cells
Amoeba Proteus
Plant Stem
Bacteria
Red Blood Cell
Nerve Cell
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Compound Light Microscope

• Has 2 sets of lenses that magnify an image.
• Each objective lens has a different magnification
  power.
• Low power 4x objective
• Med power 10x objective
• High power 40x objective
• Multiply the objective by eyepiece for total
  magnification.
• Example High Power 40 x 10 400 x