evolutionary milestones

8/14/2019 Evolutionary Milestones

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Major evolutionary

events,Prokaryotes

Ch 14, 12 (time line)

Ch 16 (prokaryotes)


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Major steps in formation of cells


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Metabolism


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First Cells

First cells were prokaryotic

3.5 bya

They were photosyntheticdidntproduce O

2

right away


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Early prokaryotes

Cyanobacteria

modified atmosphere 2.5 bya


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Eukaryotes

Origin approximately 2bya

Cells more complex

Theory of Endomsymbiosis


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Endosymbiosis

Theory proposed by Lynn Margulis


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Prokaryotic origins

of energy organelles They have double the number

of membranesinner membranes

are like prokaryotic membranes

Have their own, circular DNA

RNA, DNA and ribosomes are

similar to prokaryotes

Replicate themselvessimilar

process to binary fission


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Evolution of Multicellularity

Arose 1.2 bya


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Terrestrial organisms

~ 400mya

Origin of vascular tissue

Invertebrate animals moved on land

with them


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Cambrian Explosion 500mya


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First Cells

Prokaryotes were only cells for

1.5-2 billion years


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Prokaryotic Domains

Archaea

Bacteria

Prokaryoticno nucleus/organelles


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Prokaryotic Size

Small~1-10 m


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Prokaryotic cell parts

Glycocalyx

The outer most layer

Composed of carbohydrates and orproteins

Protects bacteria from wbc phagoctytosis

Enable cell to adhere to surfaces, stopsdehydration


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Cell Wall

Protects contents of cell

Stops nutrients leaving

Keeps cell shape

Domain Bacteria contain a lattice called a

peptidoglycan (not found in Archaea) Peptidoglycan is part of the cell wall

Amino acids and Carbohydrates


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Peptidoglycan in Domain Bacteria

monosaccharides


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Flagella (pl), Flagellum (sing.) = tail

Diff bacteria have different numbers

Some dont have one

Structure is different to sperm tail

Rotates like a boat motor, doesntwhip like a real tail


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Flagella
http://biodidac.bio.uottawa.ca/Thumbnails/showimage.cfm?File_name=Bact009b&File_type=gif


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Basal body

Hook

Filament
http://biodidac.bio.uottawa.ca/Thumbnails/showimage.cfm?File_name=Bact009b&File_type=gifhttp://biodidac.bio.uottawa.ca/Thumbnails/showimage.cfm?File_name=Bact009b&File_type=gifhttp://biodidac.bio.uottawa.ca/Thumbnails/showimage.cfm?File_name=Bact009b&File_type=gif


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Axial Filaments

Spiral shaped bacteria have axialfilaments


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Pili

Projections from the cellshorterthan flagella

Roleto adhere to surfaces

Sex Pili - used for DNA transfer(plasmid)


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Sex Pili

Horizontal

Gene Transfer


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ReproductionBinary Fission


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Endospore

Some bacteria can make an endospore

Bacillus anthracis - Anthrax
http://www.microbe.org/microbes/spores.asp


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Endospore


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Shape

Three basic shapes

Round - Cocci

Rod - Bacilli

Curved or SpiralSpirilla, Spirochete,Vibrio


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Cocci

Streptococcusin a chain

Diplococcustwo

Staphylococcusclustered


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Bacilli

Solitary Diplobacilli

Streptobacilli


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Curved or Spiral


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Nutrition

Pg326


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Photoautotrophs

Cyanobacteria


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Prokaryotes

Branched off early onvery different

Bacteria (D)

Euryarchaeota (Phylum)

Crenarchaeota (Phylum)

Eukaryota (D)

Archaea (D)


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Prokaryotic Domains


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Archaea

Phylum Euryarchaeota inc. Halophilesneed >9% NaCl Methanogensanaerobicmake CH4 from CO2, H2

or organic acidsPresent in cows, sheep, goats stomachs Phylum Crenarchaeota inc. Thermophilesvolcanic areas, V. hot, >45oC

Many live in extremeconditions


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Where do prokaryotes live?

Everywhere!

On and in all animals, plants..,surfaces, soil, streams

Also,

In extreme places - Archaea


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What do prokaryotes do?

Participate in Symbiotic relationships

Cause Disease

Decomposers/Nutrient Cycling

Environmental/Waste Clean up

Cosmetic uses

..


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SymbioticRelationships

E. coli present in our intestine

Produces Vitamin K and B vitamins in

intestine Some strains are bad, cause diarrhea


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Disease Causing Bacteria

Pathogenic

Cause disease by two mechanisms

1) Exotoxinsa secreted substance

2) Endotoxinslipid in

bacterial cell wall


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Exotoxin

Exampletetanus (Clostridium tetani)

Usually produces a neurotoxin

(tetanospasmin)released whenbacteria dies

Toxin attaches to skeletal muscle

causes uncontrollable musclecontraction, spasms

Can make vaccines using exotoxin


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Endotoxin

Food poisoning

Salmonella

All endotoxins cause fever, aches, chills


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NitrogenCycle


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Oil Slick Clean up aidedby prokaryotes


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Cosmetic Industry

BotoxClostridium botulinum

Paralyzes muscles for 3-6 months

Same bacteria that can cause botulismwhole body paralysis

Molecular


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MolecularOrganization

Amino acids mayhave beenattracted to RNAnucleotidesformed a polymer

Polymer may act as

an enzyme,attractingcomplementarynucleotides


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Lipid Spheres (Liposomes)


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Protocell

If a sphere of lipidand the

RNA/polypeptidecooperation gottogether

Bit like a cell!!

evolutionary milestones

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