Classification of Life

The Diversity of Life

Unit 6

A. Taxonomy

Def: The science of classifying organisms and giving them a universally accepted name.

1. Binomial Nomenclature: The 2-word naming system used to name all living things.

a. 1st word = The Genus: Represents a group of closely related organisms that CANNOT produce fertile offspring.

b. 2nd word = The Species: Represents a group of closely related organisms that CAN produce fertile offspring.

Ex. 1: Grizzly Bear

Genus = Ursus Species = arctos

Ursus arctos

Ex. 2: Polar Bear

Genus = Ursus Species = maritimus

Ursus maritimus

Notice these 2 animals are both bears, but cannot mate with each other to produce fertile offspring.

B. Linnaean Classification

1. Carolus Linnaeus (18th century) =Swedish botanist who developed binomial nomenclature and a system of 7 levels to classify living things.

2. The Hierarchy: 7 levels with the highest being the most INCLUSIVE and the lowest being the least INCLUSIVE.

a. Kingdom

b. Phylum = Prokaryotes, Animals

Division = Protists, Fungi, Plants

c. Class

d. Order

e. Family

f. Genus

g. Species

Example: Kingdom- Animalia, Phylum- Chordata, Class- Mammalia, Order- Carnivora, Family- Ursidae, Genus- Ursus Species- Ursus arctos

* Most levels have SUBLEVELS but this is the major framework for classifying all living things*

* Domains are used in current taxonomy, but was not used during Linnaeus’ time.

C. Phylogenetics

Def: The study of using evolutionary relationships to classify living things.

Phylogeny = Living things’ evolutionary history

1. Tool of Phylogenetics

a. Cladogram: Diagram used to show evolutionary relationships. These are based on derived characters.

- Derived characters: Things that appear in recent parts of the lineage, but not older parts.

Ex: Lungs in salamanders but not perch.

*** Structures that are USED for the same purpose but did not evolve from the same ancestor are not used in cladograms!!!!!!!

-These are called analogous structures. They evolve due to the same NEED for them.

Ex. Wings of an insect vs. wings of a bird

Molecular evidence

1. The reason structures evolve is because the INSTRUCTIONS to make them evolve!

2. Changes in DNA can be compared to see how closely related organisms are.

3. Molecular Clocks:

-Many NEUTRAL mutations occur in DNA.

-The rate (amount/time) that these occur is about the same in all organisms.

-By comparing the differences in these regions, we can see how DIFFERENT organisms are from each other.

- If the regions are different, the organisms are less related.

Classification of life

A. Domains include more types of living things than any other category.

The largest category of classification

There are 3 Domains

1. Domain Archaea

2. Domain Bacteria

*These 2 domains were previously grouped as Kingdom Monera

3. Domain Eukarya

B. Kingdoms: Each Domain is made of Kingdoms

1. Archaeabacteria

2. Eubacteria

3. Animalia

4. Plantae

5. Protista

6. Fungi

Ch. 27 - Bacteria and Archaea (Prokaryotes)

A.  Prokaryote Cell Structure

a.  All prokaryotes have:

i.  Cell membrane

ii.  Cytoplasm

iii.  Ribosomes

iv.  Nucleoid region containing DNA but DO NOT HAVE A NUCLUES!!!!

v.  Most have cell wall

b.  Some prokaryotes have:

i.  Plasmids

ii.  Pili

iii.  Flagella

iv.  Some prokaryotes form endospores that enable them to survive harsh conditions

B.  Prokaryote Classification

a.  Traditional Methods of Classification

i.  Cell Morphology (appearance)

1.  Cocci - spherical shaped cells

2.  Bacilli - rod shaped cells

3.  Spirilla - spiral shaped cells

b.  Based on Staining Characteristics

i.  Gram positive

1.  Thick peptidoglycan layer- Dyes will stick to the layer and they will be colored.

ii.  Gram negative

1.  Thin peptidoglycan layer & outer membrane- Dyes will not stick to the layer so will not be colored.

c.  Based on method of acquiring Carbon & Energy

i.  Autotrophs - acquire carbon from inorganic sources (CO2)

ii.  Heterotrophs - acquire carbon from organic sources

iii.  Phototrophs - obtain energy from the sun

iv.  Chemotrophs - obtain energy from chemicals

Chemoheterotroph = energy from chemicals, carbon from organic matter.

Chemoautotroph = energy from chemicals, carbon from CO2 (chemosynthesis)

Photoheterotroph = energy from sun, carbon from organic matter.

Photoautotroph = energy from sun, carbon from CO2 (photosynthesis)

d.  Based on Oxygen Requirements

i.  Obligate aerobe - requires oxygen to generate ATP

ii.  Obligate anaerobe - generates ATP without oxygen; oxygen is toxic

iii.  Facultative anaerobe - generates ATP with or without oxygen

e.  Based on Habitat

i.  Acidophile - prefers a low pH(1.0 - 5.4) [hot springs]

ii.  Halophile - prefers an extremely salty enviroment(3.5% -30%) [ocean]

iii.  Thermophile - prefers extreme heat [compost heaps]

C.  Modern Methods of Classification

a.  Based on molecular data.

D.  Prokaryote Gene Transfer

a.  Vertical Gene Transfer

i.  Transmission of DNA from a parent cell to daughter cells.

1.  Occurs by binary fission

b.  Horizontal Gene Transfer

i.  Transmission of DNA from one cell to another cell that is not a daughter cell

1.  Occurs by transformation, transduction, and conjugation

2.  Transformation

a.  Cell takes up DNA fragments or plasmids from the environment

3.  Transduction

a.  A virus picks up DNA from one cell and transfers it to another.

4.  Conjugation

a.  A sex pilus transfers DNA from one cell to another

E. Reproduction

a. All have asexual reproduction

i. Binary Fission (Mitosis)

“Kingdom Protista”______Biology Chapter 28

All eukaryotes, MOST unicellular, but not much else in common!

Grouped on the basis that they do not fit into any other Kingdom (exclusion)

A.  The Basal Eukaryotes

1. Basal Eukaryotes lacking mitochondria

(Ancestors probably diverged before the endosymbiotic event that created mitochondria)

·  Parabasalia – flagellated organisms found only in association with animals

·  Diplomonadida – flagellated organisms found in stagnant fresh water or in intestines

2. Basal Eukaryotes with mitochondria

* Amoebae – aquatic organisms that use pseudopodia to move and feed

* Acellular slime molds – heterotrophic organisms that exist as an amoeboid mass called a plasmodium

* Cellular Slime Molds – heterotrophic organisms that exist as single cells

* Euglenozoa – organisms that possess an anterior chamber from which one or two flagella emerge

B.  The Alveolates – have alveoli

1. Dinoflagellates – have a pair of flagella that cause the cell to spin as it swims; major components of plankton

2. Ampicomplexa – obligate parasites of animals; have complex life cycles

3. Ciliates – move by using cilia

C.  The Stramenopiles

1. Water Molds

2. Diatoms – organisms that have two-part silica walls called frustules; major components of phytoplankton

3. Brown Algae – large multicellular seaweeds

4. Golden Algae – most are unicellular

D.  The Red Algae

1. Most are marine & multicellular

2. Pigments called phycobillins give red appearance

E. The Green Algae

Plant like characteristics

·  use chlorophyll a and b

·  store starch

·  have cell walls containing cellulose

·  most exhibit alteration of generations

***Green algae differ from plants because they lack true stems, roots, and leaves***

“Kingdom Plantae”______Biology Chapters 29 & 30

Characteristics of Plants

·  Multicellular eukaryotes

·  Cell wall made of cellulose

·  Starch is primary Carbohydrate source

·  Photautotrophic

·  Most terrestrial

·  Alternation of generations = Organism is diploid (2N) for one part of its life and haploid (N) for another part… see diagrams

Evidence indicates that aquatic plants evolved from freshwater green algae (charophytes) – 476 years ago

Earliest plant fossils (476-432 million years ago) resemble liverworts

Adaptations to life on land

·  sporophyte that protects gametophyte and zygote

·  vascular tissue (xylem and phloem)

·  root systems

·  lignin

·  waterproof cuticle and stomata

A. Bryophytes

* lack vascular tissue, supportive tissue, true leaves, and stems

* asexual reproduction predominates

* gametophyte is the dominant stage

Bryophytes include the liverworts, hornworts, and mosses.

1.  Liverworts (division hepaticophyta)

2.  Hornworts (division anthocerotophyta)

3.  Mosses (division bryophyta)

B. Seedless Vascular Plants

* contain vascular tissue

* have well developed cuticle and stomata

* sporophyte is the dominant stage

Seedless vascular plants include the club mosses, whisk ferns, horsetails, and true ferns.

1.  Club Mosses – have leaves, stems, and roots

2.  Horsetails – epidermis contains silica

3.  Whisk Ferns – lacks roots (most lack leaves)

4.  True Ferns – fronds seasonally produce sori

C. Seed-Producing Vascular Plants

Origin of seeds (360 million years ago) enhanced plant survival on dry land

Two major groups:

·  Gymnosperms (cones)

·  Angiosperms (flowers)

1. Gymnosperms

* most are wind pollinated

Cycads

·  separate male and female plants (dioecious)

·  male produces large cones

Ginkgo

·  separate male and female plants

·  female produces foul smelling seeds

·  oldest extant tree species

·  no longer in wild

Conifers

·  have needle-like or scale-like leaves

·  include pine, fir, larch, spruce, juniper, and coastal redwood

Gnetophytes

may be closely related to flowering plants

include ephedra, which contains ephedrine (decongestant that also stimulates the nervous system)

2. Angiosperms

flowers

many are pollinated by insects or animals

seeds are enclosed in fruits (protect seeds and aid in dispersal)

Two major classes:

1.  Monocotyledons (monocots)

2.  Dicotyledons (dicots)

“Plant Form and Function”

A. Plant Tissues

Regions of active cell division; contain undifferentiated cells

·  Apical meristems

o  In shoots and roots

o  Allow shoots and roots to lengthen

o  Give rise to

§  Protoderm > dermal tissue

§  Procambium > vascular tissue

§  Ground meristem > ground tissue

·  Lateral Meristems

o  In older roots and shoots (woody)

o  Increase in diameter (secondary growth)

·  Intercalary Meristems

o  In bases of grass leaves

o  Allow rapid regrowth

B. Ground Tissues

Bulk of plant’s interior

·  Parenchyma cells

o  Function in cellular respiration, photosynthesis, and storage of metabolic products

·  Collenchyma cells

o  Function to support growing regions of shoots

·  Sclerenchyma cells

o  Usually dead at maturity

o  Function to support non-growing regions of plant

C. Dermal Tissue

Dermal Specializations

·  Cuticle – waxy coating

·  Stomata – pores extending through epidermis

·  Tricomes – epidermal outgrowths

D. Vascular Tissue

·  Xylem

o  Transports water and dissolved minerals from roots to shoots

o  Dead at maturity

·  Phloem

o  Transports organic compounds throughout plant

o  Alive at maturity

PLANT ANATOMY

1.  Stems

a.  Modified Stems

i.  Stolons

ii.  Thorns

iii.  Tendrils

iv.  Fleshy stems

v.  Tubers

vi.  Rhizomes

2.  Leaves

·  Leaves are classified based on form and type of venation

o  Leaf Forms

§  Simple

§  Palmate compound

§  Pinnate compound

·  Leaf Venations

o  Netted

o  Parallel

·  Modified Leaves

o  Tendrils

o  Spines

o  Bracts

o  Storage leaves

o  Insect trapping leaves

o  Cotyledon

3.  Roots

a.  Two main types

i.  Taproots

ii.  Fibrous roots

·  Modified Roots

o  Storage Roots

o  Pneumatophores

o  Aerial Roots

o  Buttress Roots

o  Prop Roots

“Kingdom Fungi”______Biology Chapter 31

Characteristics of Fungi

·  Eukaryotic heterotrophs

·  Most are multicellular (unicellular form is called a yeast)

·  Are saprotrophic or have a symbiotic relationship

·  Cell walls made of Chitin

Structure of a multicellular fungus

·  fruiting body – mass of tightly aligned hyphae (usually above ground)

·  mycelium – mass of densely branched hyphae (usually underground)

·  hyphae – septate or nonseptate

Fungi are classified into phyla based on sexual spores and fruiting bodies

A. Flagellated Fungi

* Microscopic; primarily aquatic

* Produce enzymes that degrade cellulose, chitin and keratin

* Most reproduce by forming zoospores (motile spores with a single flagellum)

B. Bread Mold Fungi

* Mostly terrestrial

C. Sac Fungi

* Unicellular

D. Club Fungi

* mostly terrestrial

E. Interspecies interactions

Many fungi interact with other organisms

1. Mycorrhizae (fungus roots)

A mutualistic relationship between fungi and plant roots

*plant obtains water from water and minerals from fungus

*fungus obtains carbohydrates from plant

2. Lichens

A mutualistic relationship between fungi and cyanobacteria or green algae

-algae/cyanobactiera obtain minerals and water from fungus

-fungus obtains carbohydrates from algae/cyanobactiera

Lichens survive in habitats that are inhospitable to either organism alone, and cannot withstand air pollution. They are sometimes used to monitor air quality.

“Animalia I” Invertebrates

Animals

·  Multicellular eukaryotes

·  Heterotrophic

·  Secrete an extracellular matrix

·  Mostly sexual reproduction

·  Most have diploid body cells and haploid sex cells

Evidence indicates that animals evolved from choanoflagellates (protists) 570 million years ago

Animals are distinguished based on

·  Body Symmetry

o  Asymmetrical- No symmetry

o  Radial Symmetry- More than 1 line of symmetry

o  Bilateral Symmetry – 1 line of symmetry (have a left & right sidedness)

·  Presence or Absence of a Body Cavity that is called a COELOM (see-lum)

A.  Porifera (sponges)

·  No true tissues

·  Asymmetry or radial symmetry

·  Aquatic (mostly marine)

·  Most are suspension (filter) feeders

·  Reproduce sexually or asexually (budding, fragmentation)

B.  Cnidaria

·  exhibit radial symmetry

·  aquatic (mostly marine)

·  predators

·  two body forms

o  polyp (attached to a surface)

o  medusa (free swimming)

C.  Platyhelminthes (planaria, flukes, and tapeworms)

·  unsegmented

·  Acoelomate (no coelom)

·  bilateral symmetry

·  free-living or parasitic

·  exhibit cephalization (have a “head” region)

·  possess protonephidra (primitive “kidneys”)

·  most are hermaphroditic (have male & female parts)

D.  Nematoda (heartworm, pinworm)

·  unsegmented

·  bilateral symmetry

·  free living or parasitic

·  reproduce sexually (separate sexes)

·  Pseudocoelom

E.  Annelida (oligiochaetes, polychaetes, and leeches)

·  segmented

·  bilateral symmetry