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