classification of living things - inetteacher.com · classification by aristotle and theophrastus...
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Classification by
Aristotle and Theophrastus
Aristotle's Classification
Air Dwellers Land Dwellers Water Dwellers
Animals
Classification by
Aristotle and Theophrastus
Theophrastus's Classification
Herbs
(soft stem)
Shrubs
(Several woddy stems)
Trees
(single woody stem)
Plants
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
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?
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.
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.
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.
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!!!
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.