Classification of Living Things by xzS9z5

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									     Classification by
Aristotle and Theophrastus

   Early Classification


     Living Things


   Plants     Animals
          Classification by
     Aristotle and Theophrastus


               Aristotle's Classification


                       Animals


Air Dwellers        Land Dwellers       Water Dwellers
         Classification by
    Aristotle and Theophrastus


              Theophrastus's Classification


                         Plants


  Herbs                 Shrubs                        Trees
(soft stem)      (Several woddy stems)        (single woody stem)
    How the 6 kingdoms came about
• At first, only two
  kingdoms were
  recognized
• Then 5 kingdoms
  (where protists had
  both plant & animal
  qualities)
• And now there are
  6 kingdoms,
  organized into 3
  domains
6 Kingdom Classification
       Kingdom Classification
• Organisms are classified based upon 4 main
  criteria:
  – How it gets food? Is it autotrophic or
    heterotrophic?
  – Is it Unicellular (one cell) or multi-cellular
    (more than one)?
  – Does it have a nucleus? Is it Prokaryotic or
    Eukaryotic?
  – Movement – Is it motile or non-motile?
Monera – Eubacteria - Bacteria
            Kingdom Monera
• Most are unicellular – some colonize
• All are Prokaryotic
• Usually classified according to shape, cell
  wall and nutrition.
  – cocci (round-shaped), bacilli (rod-shaped), and
    spirilli (spiral-shaped)
• may be photosynthetic, chemosynthetic, or
  feed by absorption.
• Asexual reproduction through Binary
  fission.
Bacterial Shape
Gram Positive (purple) vs. Gram Negative
                 (Pink)
+’ve have a thick peptidoglycan cell wall
          Reproduction - Binary Fission
• 1. As bacterial cell grows, it duplicates its’ nucleic acid.
• 2. The cell elongates and the chromosome divides.
• 3. A cell partition or septum forms between the
  chromosomes.
• 4. The septum completes itself and distinct walls form.
• 5. The cell separates into two new cells.
• This process takes as little as 20 minutes. One
  cell can become 30 000 in 5 hours.
• Prokaryotes have a single, circular chromosome
  rather than the sets of chromosomes found in the
  more familiar eukaryotes, mitosis does not occur
  in prokaryotes. Instead, most replicate via a
  process of binary fission.
Replication
                       Conjugation

• Sexual reproduction by
  bacteria.
   – Bacteria join through a pili
     that allows genetic
     information to transfer from
     one cell to another.
   – Plasmids are small loops of
     DNA separate from the main
     DNA that can move from
     cell to cell sharing its’
     genetic information.
                      Not All Bad
• Many people only consider bacteria to be the cause of
  illness and death.
• But there are beneficial bacteria:
   – in your intestine, they help digest food.
   – in cow stomachs to help them digest grass.
   – in yogurt and cheese, it curdles the milk.
   – Cyanobacteria are believed to be the first organisms to perform
     photosynthesis. They released oxygen as a waste product, and
     thus changed the composition of our atmosphere, and set the
     stage for other forms of life.
   – Other cyanobacteria are capable of fixing nitrogen into nitrates,
     an essential part of the nitrogen cycle.
   – Bacteria and algae live in symbiosis to form lichen, a major food
     source for caribou.
          Bacterial Resistance
• Antibiotics stop bacteria in a number of ways.
  They can prevent cell wall growth, some kill the
  bacteria directly and others prevent it from
  reproducing.
• Over time, bacteria mutate and evolve new strains
  resistant to antibiotics that attack them.
   – if an antibiotic kills 99.9% of bacteria, the 0.01% that is
     not affected can grow, and flourish.
• Antibiotic resistance is becoming a growing
  concern in our healthcare system.
         Kingdom Archaea

• Very similar in appearance to ‘eubacteria’;
  however, the composition of the cell walls
  and nucleic acids may be drastically
  different.
                    Types
– Methanogens- live free
  of O2 and break down
  inorganic compounds
  like H2S (hydrogen
  sulfide) and releases
  methane (CH4) as a
  waste product.
• Halophiles- salt-
  loving bacteria
• Thermoacidophiles-
  archaea bacteria that
  love and flourish in
  acidic or extreme
  temperatures.
Liard Hot Springs
• Do Page 139:
• #1, 2, 3, 4, 7, 8 and 9
Protista
       Kingdom Protista

• Most are unicellular
• Eukaryotic
• may be photosynthetic, may
  feed by absorption, or may
  ingest food.
    Classified according to nutrition

• There are three groupings for Protists (so far)
     – Protozoa (animal-like protists) : heterotrophs that
       ingest or absorb food.
     – Algae (plant-like protists) : autotrophs that carry
       out photosynthesis.
     – Slime moulds and Water moulds (fungus-like
       protists) : heterotrophic
•   Read pg 140
 Protozoa (Animal-like Protists)

• Meaning ‘first animals’
• Feed on other organisms, living or dead.
• Complex structures and reproduction
       Life Cycle – See Page 146
• Plasmodium vivax a Sporozoan human parasite is
  reposible for one type of malaria.
  – A mosquito bites an infected person, ingesting the P.
    vivax cells.
  – The gametes (reproductive cells) fuse to form a
    (diploid) zygote inside the gut of the mosquito. The
    zygote divides many times producing many spore-like
    structures (sporozites) that become released.
– The sporozoites invade the salivary glands of the
  mosquito, and are injected into a new host while the
  mosquito feeds.
– Once inside the host (human) sporozoites will
  reproduce asexually in the liver to form another
  spore-like cell. These cells then leave the liver and
  invade red blood cells, where they reproduce many
  times.
– Red blood cells rupture, releasing toxic substances
  and more spores that infect neighboring RBC’s.
      Algae (Plant-like Protists)
• Simple, aquatic,
  chlorophyll-containing
  organisms.
• Photosynthesizes
• Ranging in size from
  single celled entities to
  giants 60 meters long
  (seaweeds).
 Slime/Water Moulds (Fungus-like)

• These are difficult to
  classify. They have
  characteristics of
  fungus, plant and
  protozoa at the same
  time.
• These cute guys make
  great pets!!!
Fungi
        Kingdom Fungi

• Most multicellular, some are
  unicellular (Yeasts).
• Eukaryotic cell structure
• Absorptive Heterotrophs
• Non Motile
          Multi-cellular Structure
• The bodies are made up of a network of fine
  filaments called Hyphae. The bulk of a Fungus
  is under the soil as a branching network of
  hyphae called a mycelium.
  – Hyphae can appear as either large loosely branching
    multinucleated cells or divided into individual cells
    with walls (Septa)
• Fungi do have cell walls, but they are made with
  chitin, a material similar to the external skeleton
  of insects.
                    Nutrition

• All are heterotrophs, and most are saprophytes
  (organisms that break down dead matter).
• Fungus release digestive enzymes from their
  mycelium and absorb the digested nutrients in
  through the root system. This digestion takes
  place outside the organsim, so it is referred to as
  extracellular digestion.
                 Reproduction
• Fungi have both asexual and sexual means of
  reproduction.
• Asexual methods:
  – Fragmentation – a piece of hyphae breaks of and
    grows a new mycelia.
  – Spore formation – many fungi produce spores to be
    carried by animals or wind to new locations. Spores
    can grow directly into a new organsim.
  – Budding – a yeast cell reproduces by budding off the
    original parent. See page 157
              Zygomycota

• You have seen this mold anytime you have
  found a piece of stale bread.
• The small black dots you may have seen are
  their reproductive structures
• Like bacteria this group of fungi can perform
  sexual reproduction when conditions are
  unfavourable. They produce zygospores,
  which is where it gets its’ name.
  Life cycle of Rhizopus stolonifera

• Rhizopus have two types of hyphae:
   – Stolons – which spread out over the surface.
   – Rhizoids – penetrate deep to anchor the mold and are
     used for food absorption.
• Hyphae can also be two mating types, either a + or
  – strand. Two haploid (having only half the
  number of chromosomes) hyphae of opposite
  mating strands fuse to form a dilpoid (having the
  full number of chromosomes) zygospore.
• A thick wall develops around the zygospore to
  protect it from damage, and it will remain dormant
  until conditions are favorable for growing again.
• When conditions are right the zygospore will
  absorb water and reproduce asexually into a third
  form of hyphae called a sporangiophore that
  projects upwards, carrying on it many sporangia
  (spore-bearing capsule).
• Asexual spores develop inside the sporangia and
  are released when the capsule splits open.
The End

								
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