Biology 181 The Unity of Life

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Biology 181The Unity of Life

• Dr Lawrence Fritz
• Wettaw Biology Rm104
• 523-8265

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Biology 181

• Introduction
• Syllabus (Tentative list of topics)
• Text- Life 6th Edition
  Authors Purves, Sadava, Orians Heller
• Grading 7 in-class Quizzes, plus Final
• two (of the 7 quizzes) will be dropped
• Final must be taken
• All quizzes and Final exam are cumulative

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The Diversity of Life
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The Diversity of Life

• How many species of organisms on earth?
• but first.
• Whats a species?

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Species

• All individuals of a certain kind who are able to
  interbreed
• How many species of domestic dogs are there?
• 1
• 10
• 100
• 1000
• ??

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Species Donkey x Horse

• Results in a mule
• Therefore, are donkeys and horses the same
  species?
• but.... Mules are sterile...

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How many species on Earth?

• Surprisingly, we have a better understanding of
  how many stars there are in the galaxy than how
  many species there are on Earth.
• Estimates of global species diversity have
  varied from 2 million to 100 million species,
  with a best estimate of somewhere near 10
  million.
• Only 1.4 million have actually been named. The
  problems stemming from the limits of current
  knowledge of species diversity are compounded by
  the lack of a central database or list of the
  world's species.

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How to organize all this?

• In 1700s Linnaeus developed a hierarchical
  classification system
• Divided all organisms into 2 Kingdoms
• Plants Animals
• Then he subdivided each kingdom into
  progressively narrower groups
• Phylum, Class, Order, Family, Genus, species
  

Carl Linnaeus (1707-1778) also known as Carl von
Linné or Carolus Linnaeus, is often called the
Father of Taxonomy. His system for naming,
ranking, and classifying organisms is still in
wide use today.
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Classification System
Each and every species can now be classified by
this system

• Kingdom
• Phylum
• Class
• Order
• Family
• Genus
• species

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Binomial System

• For ease of classification recognition, we
  normally use only the last 2 names (Genus,
  species) to describe a species
• Homo sapiens
• Pinus ponderosa
• Escherichia coli
• Gorilla gorilla

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The Kingdoms of Life

• Linnaeus created 2 Kingdoms
• Whats missing?
• Today it is common to use 6 Kingdoms
• and a 3 Domain system
• See text pg. 10

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The 6 Kingdoms of Life

• Animals
• Plants
• Fungi
• Protists
• Bacteria
• Archaea

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Characteristics of Life

• A. Organization
• B. Energy use Metabolism
• C. Maintenance of internal constancy
• D. Reproduction, growth development
• E. Irritability Adaptation

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A. Organization

• All life composed of cells...The Cell Theory
• In complex organisms, cells gather to make
  tissues and organs
• Cells themselves are composed of smaller units
• organelles
• biochemicals (DNA, proteins...)

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B. Energy Metabolism

• Organization goes against the natural state of
  the universe...disorder, chaos,randomness
• buildings fall, time goes one way, life dies
• We call this tendency toward chaos...Entropy
• Entropy always increases
• Living things must fight entropy..

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How to fight Entropy?

• Energy input..
• road repairs, engine tune-ups, clean your room!
• living things use energy as metabolic reactions

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Metabolism

• Chemical reactions within cells that generate
  energy for life.
• Plants use energy from....?
• Animals use energy from foodstuffs

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C. Internal Constancy

• Life is made up of chemicals...
• Same chemicals as occur in the nonliving world.
  Yet living things maintain different amounts and
  ratios
• The outside environment is constantly
  changing...yet Living things strive to maintain
  internal composition within tight limits...

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i.e. Body Temperature

• Increases in external environmental
  temperature....
• results in sweating
• Decreased external temperature..
• restricted blood flow to skin
• End result is a constant body temperature
• homeostasis organisms ability to maintain
  constancy

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Homeodynamics

• more realistic version of homeostasis.
• takes into account the oscillations of
  physiolgical functions around a mean set point

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D. Reproduction, Growthand Development

• All living things reproduce
• a bacterium divides in two, a potato eye will
  grow a whole new plant, chop a sponge into many
  pieces and each will develop into a whole
  sponge...asexual reproduction

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Asexual Reproduction

• each of these asexual processes results in an new
  individual with identicaal traits as the
  parent....Clones
• Clones are genetically identical to each
  other....Human clones?

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Sexual Reproduction

• Two individuals combine their genetic material to
  form offspring with traits of BOTH parents.

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E. Irritability Adaptation

• Living organisms sense and respond to their
  environment
• responses to stimuli are called irritability
• touch a cactus thorn...quick response
• a dog perks up its ears
• a plant grows towards the light

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Adaptation

• longer term response to environmental stimuli
• cacti can withstand long drought periods
• on hot summer days, humans sweat while dogs pant
  (both adaptations to heat)
• camouflage is an adaptation to an
  environment..useful to hide or catch prey

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Characteristics of Life

• A. Organization
• B. Energy use Metabolism
• C. Maintenance of internal constancy
• D. Reproduction, growth development
• E. Irritability Adaptation

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These are the 5 Characteristics of Life

• Each of the 5 alone may be found in nonliving
  things...
• libraries are organized
• cars respond to stimuli
• soap bubbles can divide and even grow larger
• But living things will possess all 5 traits

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Death
Pieter Bruegel the Elder

• The absence of life....