Chapters 16-19: Diversity of Life
Transcript of Chapters 16-19: Diversity of Life
Chapters 16-19:Diversity of Life
1. Taxonomic Classification
2. Viruses and Prokaryotes
3. Protists and Fungi
4. Plants
5. Animals
1. Taxonomic Classification
The Classification of OrganismsThere are ~1.5 million known species on
our planet.• total # or species on earth estimated to be
anywhere from 7 to 100 million
To study so many organisms and their evolutionary relationships requires:
• standard nomenclature• same name used worldwide for a given organism
• hierarchy, system of classification• allows organization by “relatedness”
The Taxonomic HierarchyEach level of the hierarchy is referred to as
a taxa:
DomainKingdom
PhylumClass
OrderFamily
GenusSpecies
HumanseukaryaanimalchordatesmammalsprimateshominidsHomosapiens
The Major “Taxa”
The 3 Domains:4 Kingdomsof Eukarya:
Bacteria Archaea Eukarya
Protists, Fungi, Plants & Animals
Bacteria:• “common” prokaryotes
Archaea (or archaebacteria):• “unusual” prokaryotes or “extremophiles”• thrive in harsh environments (acid, high salt, boiling…)
Eukarya:• all organisms made of eukaryotic cells
Protists: single-celled eukaryotes
Fungi: multicellular; absorb food
Plants: multicellular; photosynthesize
Animals: multicellular; ingest food
2. Viruses and Prokaryotes
euk. cellbacteria viruses
Viruses are Small, Simple, Non-livingConsist of genetic material (DNA or RNA) inside a protein coat (may have a membrane envelope).
• no metaboliccapabilities
• reproduce onlywithin a host
• frequently “lyse”or kill host cell
Viruses come in Immense VarietyDiffer in:• size & shape
• geneticmaterial
• mode of infection
• hostspecificity
• DNA, RNA,double or single strand
AIDS Virus InfectionThe AIDS virus is a retrovirus:must convert RNA to DNA
Types of ProkaryotesProkaryotes = single-celled organisms
lacking nuclei and other organellesBacteria
• live in every conceivable environment• immense variety of metabolism, physiology• play many essential biological roles
• nitrogen fixation (all plants depend on it!)
• decomposition (essential for recycling of nutrients)
• digestion (gut flora in humans, cattle,…)
Archaea• thrive in very extreme environments
Prokaryotes come in 3 Basic Shapes
spherical(coccus)
rod-shaped (bacillus)
corkscrew-shaped(spirillum)
3. Protists and Fungi
Types of ProtistsProtists = most single-celled eukaryotic
organisms• some can form multicellular aggregates
• e.g., trypanosomes, plasmodium (causes malaria)
1) Protozoa (“first animals”)• heterotrophs (ingest food)
• amoebae, paramecia, zooplankton, trypanosomes
• many are parasites
• 2 basic types of protist:
trypanosomes
2) Algae (“photosynthetic protists”)
• phytoplankton• “seaweeds”
(dinoflagellates,diatoms, volvox)
volvoxseaweed (kelp)
diatoms
The FungiTypes of Fungiinclude:
• molds
• yeast
• mushrooms
Key Characteristics of FungiFungi digest organic material externally (they
don’t ingest food like animals do):
• secrete digestive enzymes, absorb food
• some are detritus feeders (consume deadmatter) some are parasites (prey on living)• decomposition of dead organic matter is extremelyimportant for ecosystems (recycles nutrients)
Fungal cells have cell walls (made of chitin)
Can reproduce sexually or asexually
4. Plants
What constitutes a Plant?
Major plant phyla, classes
Plants are multicellular, photosynthetic,and share characteristic modes of reproduction
The Bryophytes
Key features:
Liverworts
Mosses
• lack true leaves, roots,stems
• no internal vasculature
• rely mainly on diffusion • limits their size
The Tracheophytes
Tracheophytes are the vascular plants:• contain vessels to transport material internally
There are 3 basic types of vascular plant:
• seedless vascular plants (e.g., ferns, horsetails)
• gymnosperms (all “cone-bearing” plants)
• angiosperms (all flowering plants)
Seedless Vascular PlantsHorsetails Ferns
• most primitive vascular plant
Gymnosperms
• conifers (pines, firs, etc…), cycads, gingko
• seeds producedin cones(not flowers)
All “cone-bearing” plants:
pine
cycad
gingko
juniper
AngiospermsAll flowering plants:
• produce seeds* in flowers (via fertilization of gametes)
• most dominant type of plant*seeds are plant embryos + nutrients within a seed coat
• disperse seeds via fruits
5. Animals
Invertebrates
Vertebrates
Characteristics of AnimalsAll members of the Animal Kingdom:
• consume food derived from other organisms• feed by “ingesting” food
• unlike fungi which “absorb” food externally
• consist of eukaryotic cells w/o cell walls• are heterotrophs
Most members of the Animal Kingdom:
• are multicellular
• have a symmetrical body plan• radial or bilateral symmetry
• have distinct tissues, organs• reproduce sexually
Radial vs Bilateral SymmetryRadial Symmetry
• symmetrical halves “no matter how you slice it”
Bilateral Symmetry• only one
plane of symmetry
symmetry as viewed from the dorsal (back)or ventral (belly) sides
Vertebrate vs InvertebrateVertebrate animals
• have a backbone or “vertebral” column• less than 3% of known animal species
Invertebrate animals• NO backbone or “vertebral” column• > 97% of known animal species• any “non-vertebrate” animal
The vertebrate/invertebrate distinction is somewhat “old school”
They more or less constitute “sub-kingdoms”
Major Invertebrate Phyla“Lower” Invertebrates
Porifera• all sponges
Cnidarians• anemones, coral, jellyfish
Platyhelminthes• all “flatworms”
Nematodes• all “roundworms”
“Higher” Invertebrates
Annelids• all “segmented worms”
Mollusks• snails, clams, squids
Arthropods• insects, spiders, crabs
Echinoderms• starfish, sea urchins
The Phylum ChordataMain characteristics of the Chordates:
• have a notochord• usu. gives rise to the backbone during development
• have a hollow nerve cord• becomes brain & spinal cord during development
• pharyngeal “gill slits”• may disappear during development
• have a tail• may disappear during development
***All vertebrates are chordates but not all chordates are vertebrates***
Major Chordate Classes
Agnatha• “jawless” fishes
Chondrichthyes• cartilagenous fishes
Osteoichthyes• bony fishes
Amphibians• frogs, salamanders…
Reptiles• lizards, snakes, turtles…
Birds (Aves)• chickens, eagles…
Mammals• humans, cats, dogs…
Key Terms for Chapters 16-19• taxa, domain, kingdom, phylum…
• bacteria, archaea, eukarya, fungi, protists• bacillus, coccus, spirillum• protozoa, algae
• bilateral vs radial symmetry, vertebrate vs invertebrate
Relevant Review Questions: ch. 16 – 3, 6; ch. 17 – 3, 5, 9
ch. 18 – 1, 3-5, 7-15; ch. 19 – 3