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Classification
A. Why Classify? ◦ 1. organization makes it easier to understand and find information ◦ 2. taxonomy – scientists classify organisms and assign each organism a universally accepted name – by using a scientific name, scientists can make sure everyone is discussing the same organism
B. Assigning Scientific Names ◦ 1. Carolus Linnaeus – a Swedish botanist who lived during the 18th century developed a two-word naming system called binomial nomenclature – this system is still used today – in binomial nomenclature, each species is assigned a two-part scientific name – the scientific name is always written in italics and the first word is capitalized, and the second word is lower case
For example, the grizzly bear is called Ursus arctos The first word in the scientific name is the genus and the second word is the species
C. Linnaeus’s System of Classification ◦ 1. Linnaeus’s classification system consists of levels which is called hierarchial – it includes seven levels From largest to smallest: (each level is called a taxon)
Kingdom
Phylum
Class
Order
Family
Genus
Species
◦ 2. Each taxon: (a) Kingdom – the largest and most inclusive of the categories – Linnaeus named two kingdoms – Animalia and Plantae
(b) Phylum – include many different organisms that share important characteristics – for example, Chordata
(c) Class – for example, Mammalia, Amphibia, Reptilia
(d) Order – for example, Carnivora
(e) Family – share many characteristics – for example, Canidae (dogs) and Felidae (cats
(f) Genus – a group of closely related species – for example, Ursus
(g) species – unique to each species – smallest group – for example, arctos or maritimus
Ursus arctos - Grizzly bear
Ursus maritimus – Polar bear
A. Although physical characteristics are useful for classification, problems arise. It is better to use other similarities.
B. evolutionary classification – called phylogeny – Biologists now group organisms into categories that represent lines of evolutionary descent, or phylogeny, not just physical similarities.
C. Similarities in DNA and RNA – can be used to help determine classification and evolutionary relationships
D. Kingdoms ◦ 1. Five-kingdom system - Monera, Protista, Fungi, Plantae, and Animalia
◦ 2. Six-kingdom system – recently, the kingdom Monera has been split because there are two distinct groups – Eubacteria, Archaebacteria, Protista, Fungi, Plantae, and Animalia
◦ 3.Some classification systems have added a domain above the kingdom – these three are bacteria, arachaebacteria, and eukaryotes
A. Humans ◦ Kingdom – Animalia ◦ Phylum – Chordata ◦ (subphylum – vertebrata) ◦ Class – Mammalia ◦ Order – Primates ◦ Family – Hominidae ◦ Genus – Homo ◦ Species - sapiens
A. prokaryotic B. single celled C. lack true nuclei D. lack a cytoskeleton E. contain double-stranded circular
chromosomal DNA that is not enclosed by a nuclear membrane
F. nourish themselves a. heterotrophically by feeding on dead materials
(saprophytically)
b. heterotrophically by attaching and feeding on living things (parasitically)
c. autotrophs where they make their own food.
G. Structure Have cell walls made of peptidoglycan - a type of
carbohydrate and peptide – use gram staining to identify the strength of the cell wall – gram positive cells have a thick wall that stains strongly while gram negative cells have a thin cell wall and an outer membrane that stains poorly. classified by their appearance
a. cocci – round
b. bacilli – rods
c. spirilla – spiral
May come in duplexes (diplococci), clusters (staphylococci), or chains (streptococci)
Archaebacteria – have no organelles and have a simple circular DNA ◦ 1. Relatively unknown until recently ◦ 2. Tend to inhabit harsh environments like hot springs
that might resemble the early earth ◦ 3. Different from eubacteria in their membranes
lipids
Kingdom Protista– simplest of the eukaryotic organisms – probably represents the evolution between prokaryotes and the rest of the eukaryotic kingdoms ◦ 1. most are unicellular ◦ 2. examples: amoeba, paramecium, euglena, algae,
slime molds ◦ 3. some are mobile through cilia, flagella, and ameboid
movements ◦ 4. some use sexual reproduction while others use
asexual reproduction
Examples of kingdom protista ◦ 1. amoebas – large single-celled organisms that do not
have a specific body shape Change shape through the movement through the
movement or streaming of their cytoplasm (called cyclosis) – the extensions of the amoeba are called pseudopods
Heterotrophs that feed by engulfing food through a process called phagocytosis (active transport) – creates a food vacuole
Examples of Kingdom Protists ◦ 2. ciliates – complex, single-celled organisms such as
the paramecium Surface is covered with cilia that move the cell through
water like the oars of a boat
Have a defined shape
Have contractile vacuoles to remove excess water
Food enters through an oral groove where it forms food vacuoles
Reproduce asexually through mitosis
Can also exchange genetic material through conjugation
Examples of Kingdom Protista ◦ 3. slime molds – in some cases, slime molds are
grouped with fungi Heterotrophs
Some slime molds spend time as independent cells while others gather together to form multicellular forms that produce spores
Examples of Kingdom Protista ◦ 4. algae – photosynthetic protists
Mostly unicellular
Include diatoms – single celled organisms with intricate silica cells
Include dinoflagellates with flagella
Include brown and red algae Algae can reproduce sexually and asexually
Includes giant kelp that is multicellular (may be grouped as a plant also)
Kingdom Fungi – heterotrophs that absorb nutrients from the environment ◦ Often saprophytic – feed off dead materials ◦ Important because they help recycle nutrients ◦ Enzymes are secreted onto the dead material to
digest the food then the nutrients are reabsorbed into the fungus
◦ Cell wall is made of chitin (unlike the cellulose in plants)
◦ Often form long slender filaments called hyphae ◦ Most reproduce both sexually and asexually ◦ Examples are mushrooms, molds, and yeasts
Kingdom Plantae ◦ Multicellular eukaryotes that produce energy through
photosynthesis ◦ Cell wall made of cellulose ◦ Plants are nonmotile ◦ Adapted for maximum exposure to light, air, and soil ◦ Increase in the ability to resist gravity and tolerate
drier conditions ◦ First plants probably evolved from green algae in or
near shallow water
◦ Nontracheophytes – plants without water transport systems – also lack woody stems – their lack of transport systems restricts their size and restricts their habitat to moist environments
◦ Evolution of vascular systems (transport systems) was a major adaptation in plants – the first vascular plants were called tracheophytes – did not produce seeds - for example, ferns and horsetails – released spores
◦ Evolution of the seed was the next major step in plant evolution – increases the plants ability to deal with the variable conditions on land – plants are formed as the result of fertilization of male and female gametes
◦ Evolution of the flower was next – allows for extra nutrition for the developing embryo
Kingdom Animalia – multicellular heterotroph ◦ Over time animals have become more complex with
great specialization of tissue – nervous systems have become more complex also
◦ Different body shapes 1. radial symmetry – organized with their body in a
circular shape radiating outward such as sea stars and jellies
2. bilateral symmetry – the body has a left side that is a mirror image of the right side
◦ Some animals are sessile (don’t really move) like the hydra – most of these animals are filter feeders or use their tentacles to capture food - requires very little energy – at the mercy of the environment
◦ Animals that do move have complex nervous systems
Phylums in the Animal kingdom 1. Phylum porifera (sponges) ◦ First evolutionary step between protists and animals ◦ Resemble organisms that live in a colony ◦ Only a small amount of specialized cells ◦ No organs ◦ Only have a few types of cells ◦ No nervous system ◦ Can regenerate
Phylums in the Animal Kingdom 2. phylum Cnidaria (hydra, sea anemone, jellies) ◦ Cnidarians are called coelenterates ◦ Have radial symmetry ◦ Aquatic animals ◦ Only two cell layers – do not need circulatory or respiratory
systems ◦ Have a simple nervous system ◦ Have stinging cells called nematocyst ◦ Start out as a polyp that lives attached and then become a
medusa that is free floating ◦ May reproduce sexually or asexually
Phylums in the Animal Kingdom 3. phylum Platylhelminthes (flatworms) ◦ Ribbonlike with bilateral symmetry ◦ Posses three layers of cells ◦ Lack a circulatory system ◦ Nervous system – simple light detection organs, an
anterior brain ganglion, and a pair of longitudinal nerve cords
◦ Digestive system – a cavity with a single opening ◦ Not swift moving – use cilia to move ◦ Some are able to regenerate – example: planaria ◦ Many are parasitic – flukes, tapeworms
Phylums in the Animal Kingdom 4. phylum Nematoda (roundworms) ◦ Three layers ◦ Complete digestive tract with a mouth and an anus ◦ Do not have respiratory or circulatory systems –
exchange gases directly with the environment ◦ Has movement in one direction ◦ One of the most abundant groups ◦ Many are free-living but some are parasites
Phylums in the Animal Kingdom 5. phylum Annelida (segmented worms) ◦ Earthworm and leeches ◦ Segmented bodies ◦ Have a body cavity ◦ Has movement that is coordinated by the nervous
system – has nerve cord and ganglion of nerve cells that function as a brain
◦ Exchange gases directly with the environment through their skin
◦ Has excretory system ◦ Has a closed circulatory system with 5 hearts
Phylums in the Animal kingdom 6. phylum Arthopoda ◦ Jointed appendages ◦ Exoskeleton made of chitin ◦ Open circulatory system ◦ Three classes – insects, arachnids, and crustaceans ◦ Has a respiratory system ◦ Has complex sensory organs ◦ One of the most varied and abundant groups
Phylums in the Animal Kingdom 7. phylum Mollusca ◦ Clams, squid, snails ◦ Muscular foot ◦ Mantle that secretes a shell ◦ Rasping tongue called a radula ◦ Most are covered by a hard shell ◦ Some have a reduced inner shell ◦ Mostly aquatic and breath through gills
Phylums in the Animal Kingdom 8. phylum echinodermata ◦ Include sea stars and sea urchins ◦ Spiny ◦ Have radial symmetry ◦ Have ability to regenerate ◦ Have a water vascular system – used along with tube
feet to hold onto objects and move ◦ Have a hard internal skeleton made of calcium
deposits
Phylums in the Animal Kingdom 9. phylum Chordata ◦ Have a stiff, solid dorsal rod called a notochord ◦ Have ventral heart ◦ Subphylums –
Vertebrates
Examples: Reptiles, Birds, mammals,
