CLASSIFICATION OF ORGANISMS

1
CHAPTER 23 CLASSIFICATION OF ORGANISMS
2
CLASSIFICATION OF ORGANISMS

• 30 million species are estimated to live on Earth
• Only 1.5 million have been named
• Taxonomy science of naming organisms and
  grouping them into categories
• First developed by Aristotle
• Modern method developed by Carolus Linnaeus (1758)

3
CLASSIFICATION

• Linnaeus introduced the system of binomial
  nomenclature.
• Each organism gets two Latin names (genus and
  species)
• Species organisms that can interbreed
• Genus - many closely related organisms
• Scientific names must be written in italics or
  must be underlined
• genus name is capitalized
• species name is written in lower case
• Homo sapiens or Homo sapiens (humans)

4
CLASSIFICATION OF ORGANISMS

• Linnaeus also placed organisms into taxonomic
  categories, the largest of which is the kingdom.
• Were originally two kingdoms animals plants
• Recently a grouping above kingdom, called domain,
  was introduced.
• Organisms are now placed into 3 domains
• Eubacteria
• Archaea
• Eucarya
• Each domain is subdivided into kingdoms

5
CLASSIFICATION OF ORGANISMS

• Domain Eucarya has 4 kingdoms
• Plantae
• Animalia
• Fungi
• Protista
• A kingdom is further subdivided into a phylum
  (known as a division in Plantae)
• Further subdivisions are class, order, family,
  genus, and species
• Hierarchy of classification domain, kingdom,
  phylum (division), class, order, family, genus,
  and species.

6
DOMAINS EUBACTERIA AND ARCHAEA

• Members are commonly known as bacteria
• Though similar, the two domains have significant
  differences in metabolic activities.
• Some are disease-causing, most are not
• Differences between the two are based on DNA and
  RNA sequences

7
EUBACTERIA

• Three common shapes
• spherical
• rod
• spiral
• Classified as prokaryotes, characterized by
• no nucleus
• single, circular strand of DNA
• reproduce by binary fission
• move by flagella or slime they produce
• some are aerobic and others anaerobic
• some are parasites
• some are saprophytes (decomposers)

8
BINARY FISSION IN BACTERIA
9
ARCHAEA

• Ancient prokaryotic bacteria, but differ from
  regular bacteria in that
• Found in extreme environments such as
• hot springs at 113º C (above boiling point)
• high salt
• acidic places
• Some have special kinds of chlorophyll

10
EUCARYA

• Eukaryotic cells are larger than those of
  prokaryotes (1000 times more volume)
• Cells have membrane-bound organelles
  (mitochondria, ER, Golgi, lysosomes, etc.)
• Eucarya are divided into
• Protista
• Fungi
• Plantae
• Animalia

11
PROTISTA

• All are single celled
• Approximately 60,000 different species
• Found in fresh water, marine, and terrestrial
  habitats
• Many have chlorophyll and are autotrophs
• Some reproduce sexually

12
FUNGI

• Have a rigid, thin cell wall composed of chitin
  over 70,000 species
• Do not have chlorophyll Nonmotile
• Include molds and mushrooms most are
  multicellular
• Some are single-celled (yeasts)
• Function mainly as decomposers (saprophytes)
• Some are parasitic

13
PLANTAE

• All are nonmotile, terrestrial, multicellular
  organisms capable of producing their own food
• Have cellulose in their cell walls
• 300,000 species have been identified and of
  these, 85 are flowering plants
• Members of this group can be vascular or
  nonvascular.
• Some are seed producing, some (ferns) lack seeds

14
PLANTAE

• Have unique lifecycles
• Haploid gametophyte stage produces haploid sex
  cells by mitosis
• Diploid sporophyte stage produces haploid
  spores by meiosis.
• Capable of both sexual and asexual reproduction

15
ANIMALIA

• All are heterotrophic and multicellular
• All are motile (at least during some part of
  their life)
• All are capable of reproducing sexually, but some
  can reproduce asexually

16
VIRUSES

• Consist of a nucleic acid core surrounded by a
  coat of protein (capsid)
• Obligate intracellular parasites
• Are not members of any domain or kingdom
• Not considered living things
• Reproduce only when they are in their host cell

17
VIRUSES

• Once inside a cell, viral nucleic acids take over
  the cell and direct it to make more viral
  particles
• Viruses are host-specific
• Only infect certain hosts
• Only infect certain cells
• Have either DNA or RNA as their nucleic acid (not
  both)
• Smallest infectious agents known to humans

18
VIRUSES

• Viruses bind to the host and either
• Inject its nucleic acid, or
• Are engulfed through endocytosis
• In either case, the protein coat is released and
  the nucleic acid will replicate using the
  machinery of the host cell.
• Once new viral particles are assembled, the host
  cell is destroyed and new viruses are released to
  infect other cells.

19
TYPICAL VIRUSES
20
VIRUSES

• One of the most recent infectious viruses is HIV.
• Only infects humans
• Causes AIDS
• claimed 22 million lives so far
• HIV is a spherical virus containing RNA, a
  protein shell, and an outer envelope
• Estimated to be over 42,500,000 people infected
  with the AIDS virus

21
(No Transcript)
22
VIROIDS

• Similar to viruses, but consist only of a single
  strand of RNA
• None infect animals
• Mainly infect cultivated crops
• Potatoes
• Tomatoes
• Cucumbers
• Hard to detect
• Stunted or distorted growth, may or may not cause
  plant death
• Spread very easily

23
PRIONS

• These are infectious proteins that can be passed
  from one individual to another
• Not species-specific can be passed between
  species
• Examples include
• scrapie in sheep and goats
• mad cow disease in cattle (BSE)
• chronic wasting disease in deer and elk

24
PRIONS

• Epidemic of mad cow disease in Great Britain was
  apparently caused by the spread of prions from
  sheep to cattle
• Prion-caused diseases in humans include
• Kuru occurred in Papua New Guinea and spread by
  eating the brains of their dead
• Creutzfeldt-Jakob disease transmitted by
  surgical instruments and tissue transplants
• Similar to mad cow disease
• Causes holes in brain matter

25
PRIONS

• Do not reproduce or replicate as do viruses and
  viroids
• May cause a normal protein to change shape to
  that of a dangerous protein
• Proteins may stack up and interlock forming
  plaques
• Finally results in death

26
CHAPTER 23 CLASSIFICATION OF ORGANISMS
27
(No Transcript)
28
(No Transcript)
29
(No Transcript)
30
(No Transcript)
31
(No Transcript)
32
(No Transcript)
33
(No Transcript)
34
(No Transcript)
35
(No Transcript)
36
(No Transcript)
37
(No Transcript)
38
(No Transcript)
39
(No Transcript)
40
(No Transcript)
41
(No Transcript)
42
(No Transcript)
43
(No Transcript)
44
(No Transcript)
45
(No Transcript)
46
(No Transcript)
47
(No Transcript)
48
(No Transcript)
49
(No Transcript)
50
(No Transcript)