The Origin of Life

• Life originated 3.5-4.0 billion years ago!

What came first: prokaryotic cells or

eukaryotic cells?

Prokaryotes

• Prokaryotes dominated life on Earth from 3.5-2.0 bya!– The 1st actual cells

3.5 billion year old fossil of bacteria Modern bacteria

Chains of unicellular cyanobacteria

The Origin of Eukaryotic Cells

Bacteria were the starting point for all the life we have today!

How many species exist on Earth?

• We don’t know an exact number – MILLIONS

• More still waiting to be discovered!

How do we keep track of all of them?

Classifying Organisms

Devil Cat

Ghost Cat

Mountain Lion

Screaming Cat

Puma

Florida Panther

Cougar

All the same species!

• There are at least 50 different names for the species of cat shown before.– Different places have different

names.

• Scientific name: Felis concolar– Why is it important to have

scientific names?

Scientific Names

• Give species an “official” name

• Come from “dead” languages – Latin or Greek

• We get the names from the way the organisms are classified.

Solenopsis invicta

TaxonomyClassifying Living Organisms

Taxonomy

• The science of classifying organisms– Show how organisms are

related– Provides a universal system

for identifying organisms– Provides scientific names

We use the Linnaean system for classifying organisms.

A good way to remember…

KingPhillipCameOverForGoodSoup

What is the order of the Linnaean classification system?

A. Kingdom, Phylum, Genus, Class, Order, Family, SpeciesB. Kingdom, Family, Phylum, Genus, Order, Class, SpeciesC. Kingdom, Phylum, Class, Genus, Order, Family, SpeciesD. Kingdom, Phylum, Class, Order, Family, Genus, Species

King Phillip Came Over For Good SoupKingdom, Phylum, Class, Order, Family, Genus, Species

Linnaean Classification

• System for classifying organisms by hierarchy - goes from broad to specific!

All Living Species

Animalia

Plantae

Fungi

Protista

Eubacteria

Archaebacteria

All living species can be broken down into 6 kingdoms:

1. Animalia2. Plantae3. Fungi4. Protista5. Eubacteria6. Archaebacteria

Each of these kingdoms can be broken down into phylums!

Human Linnaean Classification

Notice how we went from broad

categories to specific categories!

Kingdom Animalia contains many species!

Some animals have a backbone, some don’t.

Phylum Chordata (backbone) includes several mammals.

Some mammals are carnivores.

Several carnivorous mammals are bears.

Some bears are more closely related than others…

We’ve narrowed it down to a specific species!

Binomial Nomenclature

• Formal system for naming species– Latin or Greek– Italicized– Genus species

Turdus migratorius, or American Robin

What genus does the American Robin belong to?

Turdus!Remember that species get their

scientific names from their classification – Genus species

A. AmericanB. RobinC. TurdusD. Migratorius

Turdus migratorius

Which species are more closely related?

Polar & Grizzly Bear – they belong to the same genus!

A. Panda & Polar BearB. Polar Bear & Grizzly BearC. Grizzly Bear & Panda

Which of the following is true?

A. All animals are chordates.B. All felines belong to the

genus Panthera.C. All chordates are

mammals.D. All felines are carnivores.

Which category in the Linnaean System is the most specific?

A. PhylumB. FamilyC. ClassD. Genus

Genus!

33

Broad

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