Life’s Origin and Life’s Origin and Classifying Classifying OrganismsOrganisms

Where does life come from?Where does life come from? Spontaneous GenerationSpontaneous Generation

– Belief that living things Belief that living things could come from non-could come from non-living organisms.living organisms.

– Was accepted for 100’s Was accepted for 100’s of years until controlled of years until controlled experiments proved it experiments proved it wrongwrong

– Believed from the 4Believed from the 4thth century until the 1600’s.century until the 1600’s.

SCIENTISTS USE SCIENTISTS USE EXPERIMENTAL DESIGNEXPERIMENTAL DESIGN

SPONTANEOUS GENERATION FIRST SPONTANEOUS GENERATION FIRST DISPROVED BY ITALIAN SCIENTISTDISPROVED BY ITALIAN SCIENTIST

FRANCESCO REDI -FRANCESCO REDI -http://www.sumanasinc.com/webcontent/animations/content/scientificmethod.html JOHN NEEDHAM PERFORMED THE HEATED BROTH JOHN NEEDHAM PERFORMED THE HEATED BROTH

EXPERIMENTEXPERIMENT LAZZARO SPALLANZANI BROILED BROTH IN FLASK FOR LAZZARO SPALLANZANI BROILED BROTH IN FLASK FOR

LONGER TIMELONGER TIME LOUIS PASTEUR DISPROVED SPONTANEOUS GENERATION LOUIS PASTEUR DISPROVED SPONTANEOUS GENERATION

FOR THE LAST TIMEFOR THE LAST TIME

http://www.youtube.com/watch?v=JHZwMxmLHnk

What Is Life?

Redi’s ExperimentFrancesco Redi designed one of the first controlled experiments. Redi showed that flies do not spontaneously arise from decaying meat.

What Is Life?

Pasteur’s ExperimentLouis Pasteur’s carefully controlled experiment demonstrated that bacteria arise only from existing bacteria.

Where does life come from?Where does life come from?

BiogenesisBiogenesis–Theory that living things can Theory that living things can only come from other living only come from other living things. things.

Life’s OriginsLife’s Origins

Scientists Scientists estimate estimate the earth to the earth to be around be around 4.6 billion 4.6 billion years old.years old.

Oparin’s HypothesisOparin’s Hypothesis

Russian scientistRussian scientist Hypothesized in 1924 that Earth’s Hypothesized in 1924 that Earth’s

early atmosphere had no oxygen- early atmosphere had no oxygen- was made of gases ammonia, was made of gases ammonia, hydrogen, methane, and water hydrogen, methane, and water vapor. These combined to form more vapor. These combined to form more complex compounds.complex compounds.

Stanley Miller and Harold Stanley Miller and Harold UreyUrey

Tested Oparin’s Tested Oparin’s hypothesis in hypothesis in 1953. Showed, but 1953. Showed, but did not conclude, did not conclude, that chemicals that chemicals found in living found in living things could be things could be produced this way.produced this way.

http://www.youtube.com/watch?v=j9ZRHoawyOg

Stanley Miller Harold Urey

Monday SSW25

1. Compare and contrast spontaneous generation and biogenesis.

2. Name two scientists who contributed to these theories.

3. Which scientist was responsible for finally putting spontaneous generation to rest?

Why do Scientists Classify?Why do Scientists Classify?

Imagine a grocery store…Imagine a grocery store…

How are they organized?How are they organized?

What would happen if What would happen if they were not organized?they were not organized?

How is your life organized?How is your life organized?

Why do Scientists Classify?Why do Scientists Classify?

Almost 2 million kinds of organisms on Almost 2 million kinds of organisms on EarthEarth

Need to keep Need to keep organized!organized! (Easier to (Easier to study!)study!)

ClassificationClassification

= process of grouping things based on = process of grouping things based on their similaritiestheir similarities

Why do Scientists Classify?Why do Scientists Classify?

TaxonomyTaxonomy

=scientific study of how living things =scientific study of how living things are classifiedare classified

Useful because:Useful because:

once classified, scientists will know a once classified, scientists will know a lot about an organismlot about an organism

Early Classification SystemsEarly Classification Systems

Aristotle (4Aristotle (4thth century B.C.) century B.C.)

--observedobserved animals animals

-watched appearance, -watched appearance, behaviorbehavior, , movementmovement

-fly, swim, and walk/crawl/run-fly, swim, and walk/crawl/run

-observed similarities and differences-observed similarities and differences

-used differences to divide into -used differences to divide into smaller smaller subgroupssubgroups

Aristotle and ClassificationAristotle, an ancient Greek scholar, developed a classification system for animals.

Classifying Life

LinnaeusLinnaeus

Carolus Linnaeus (1750s)Carolus Linnaeus (1750s)

-used observations as basis of his -used observations as basis of his systemsystem

-placed organisms based on -placed organisms based on similarsimilar structuresstructures

Devised naming system for organisms:Devised naming system for organisms:

Binomial NomenclatureBinomial Nomenclaturehttp://www.youtube.com/watch?v=opWd01DuW28&feature=related

Classification TodayClassification Today

Species with similar evolutionary histories Species with similar evolutionary histories are classified more closely together.are classified more closely together.

-when organisms share a common ancestor, -when organisms share a common ancestor, they share an they share an evolutionaryevolutionary history history

-Before classifying an organism scientists -Before classifying an organism scientists look at its look at its phylogenyphylogeny (evolutionary history) (evolutionary history)

- fossils- fossils

- DNA- DNA

- early stages of development - early stages of development

Modern ClassificationModern Classification

Today’s classification system Today’s classification system separates organisms into six separates organisms into six kingdomskingdoms..

Kingdoms are the first and Kingdoms are the first and largestlargest categorycategory

Smallest category is Smallest category is speciesspecies Organisms that belong to the same Organisms that belong to the same

species can mate and produce species can mate and produce offspring.offspring.

The Old SystemThe Old System

6 Kingdom Proposal6 Kingdom Proposal

Archebacteria

EUbacteria

Binomial NomenclatureBinomial Nomenclature

=2 part naming system used by =2 part naming system used by LinnaeusLinnaeus

-uses Latin words-uses Latin words

First word- Genus- is capitalizedFirst word- Genus- is capitalized

Second word- Second word- speciesspecies- is NOT.- is NOT.

If you can’t italicize, If you can’t italicize, underlineunderline the the genus and species!genus and species!

Scientific NameScientific Name

Genus species Genus species Felis concolorFelis concolor– AKA cougar, panther, puma, mountain AKA cougar, panther, puma, mountain

lionlion

The second word tells something The second word tells something about the species:about the species:– What it looks like, where it is found, or What it looks like, where it is found, or

who who discovered itdiscovered it

Why use scientific names?Why use scientific names?

To avoid mistakesTo avoid mistakes To show how organisms are relatedTo show how organisms are related To give descriptive information (Ilex To give descriptive information (Ilex

vomitoria)vomitoria) To allow information to be organized To allow information to be organized

easilyeasily

Three Domains of LifeBacteria and Archaea are unicellular organisms that have no nucleus. Organisms with cells that contain nuclei are called Eukarya.

Domains and Kingdoms

Levels of ClassificationLevels of Classification-based on contributions of both -based on contributions of both

Aristotle and LinnaeusAristotle and Linnaeus

Today there is a three domain system Today there is a three domain system of classification: Bacteria, Archea, of classification: Bacteria, Archea, EukaryaEukarya

Eukarya is broken down into 4 Eukarya is broken down into 4 kingdoms: Protists, Fungi, Plants, kingdoms: Protists, Fungi, Plants, AnimalsAnimals

There are 8 levels of There are 8 levels of classificationclassification. .

Remember the first letter of this Remember the first letter of this sentence:sentence:

DDumbumb K King ing PPhilip hilip CCame ame OOver ver FFor or GGood ood SSpaghetti.paghetti.

http://www.youtube.com/watch?http://www.youtube.com/watch?v=6jAGOibTMuU&feature=relatedv=6jAGOibTMuU&feature=related

8 Levels of Classification8 Levels of ClassificationDDomainomain

KKingdom ingdom broadest levelbroadest level

PPhylumhylum

CClasslass

OOrderrder

FFamilyamily

GGenus enus

SSpeciespecies most specificmost specific

Levels of ClassificationThe number of organisms on each level decreases as the levels of classification get lower and the organisms share more characteristics with each other and are related.

Using the Classification Using the Classification SystemSystem

Field guides help identify Field guides help identify organismsorganisms..-they highlight differences between -they highlight differences between similar organisms (like trees) give similar organisms (like trees) give descriptions and descriptions and illustrationsillustrations

TaxonomicTaxonomic Key (AKA Dichotomous Key) Key (AKA Dichotomous Key)-paired statements that describe the -paired statements that describe the physical characteristics of different physical characteristics of different organisms- detailed listorganisms- detailed list

Classifying Life

Identifying OrganismsThe six paired statements in this taxonomic key describe physical characteristics of different organisms.

Dichotomous KeysDichotomous Keys

1a. Organism has 4 legs Go to # 2

1b. Organism has more than 4 legs Go to # 20

2a. Organism has a tail Go to # 3

2b. Organism has no tail Go to # 35

3a. Organism has stripes Bengal Tiger

3b. Organism has no stripes African Lion

Dichotomous KeyDichotomous Key Try this one:Try this one:

1a. Organism walks on all 4 legs (quadruped) 2

1b. Organism walks on 2 legs (biped) 8

2a. Organism has visible fur 3

2b. Organism has no visible fur 20

3a. Organism lives in warm climates 7

3b. Organism lives in cold climates 4

4a. Organism has brown or black fur Ursus americanus

4b. Organism has white fur Ursus maritimus