Transcript Classification of Living Things

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
(soft stem)
Shrubs
(Several woddy stems)
Trees
(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- saltloving bacteria
• Thermoacidophilesarchaea 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