Ch.26/27

• I. History of life• A. Earth formed about 4.5 billion years

ago• B. Life began a few 1,000,000 years

later• 1. Metabolic activity found in 3.5 billion year old rocks• 2. 3.5 billion year old fossils have been found

• C. Major happenings• 1. RNA sequence data

shows 2 distinct groups of prokaryotes which split about 2 billion years ago.

a. Archeabacteria

b. Eubacteria

• 2. 2.5 billion years ago production of oxygen created an aerobic environment.

– a. More diversity exists between prokaryotes than all eukaryotes combined.

Probionts

• 3. 2.2 billion years is the oldest fossils of eukaryotes

– a. Mitochondria and chloroplasts were probably cells within cells. ( endosymbiosis)

– b. RNA was probably the first genetic material

• 4. Plants arose from green algae

• 5. Fungi and animals arose from different groups of heterotrophic organisms.

– a. Molecular evidence suggests animals are more closely related to fungi than to plants.

– b. Oldest animal fossils are invertebrates from 700 million years ago.

• 6. Plants and fungi came on land about 475 million years ago

• There is a lot of speculation on how life first came to be and the subject is still open to debate.

• D. RNA: the first genetic material• 1. Now it is DNA->RNA->protein

2. A more simple version would have been RNA-> protein– a. RNA has been found to act like a catalyst and these are called

ribozymes.

Endosymbiosis

• II. The major lineage's of life• A. The 5 kingdom system recognizes to

fundamentally different types of cells, prokaryote and eukaryote.

• 1. Kingdom Monera - lumps all bacteria together– 2. The plant, fungi and animal kingdoms are all

multicellular organisms.

Ch.26 Domains

• a. Plants are autotrophic

• b. Fungi are heterotrophic but absorb their food

• c. Animals are heterotrophic but ingest and digest

• 3. The protist kingdom contains all the single celled eukaryotes and any that did not fit the other kingdoms.

• B. The domains• 1. Superkingdoms _Bacteria, Archaea and

Eukarya also referred to as domains

Ch. 27Prokaryotes

• I. The two main branches of prokaryotes

A. Archea - means ancient- thought to be most likely the earliest cells, but wrong.

• B. Eubacteria• C. Shapes and sizes of

prokaryotes• 1. spheres- cocci (go

ahead laugh now and get it out of your system)

• 2. rods- bacilli• 3. helices

Conjugation ch.27

• D. Reproduction• 1. binary fission• 2.Transformation-_genes taken

up from surroundings, like pGlo_• 3.Conjugation-_transfer of genes

from one prokaryote to another

4.Transduction-genes from virus acquired by bacteria

• E. Nutrition• 1. Photoautotrophs =Photosynthesis yields organic compounds

• 2. Chemoautotrophs - oxidize chemicals like, hydrogen sulfide and ammonia instead of using light for energy (only found in

prokaryote nutrition)• 3. Photoheterotrophs - use light and organic compounds, can not use

carbon dioxide.• 4. Chemoheterotrophs - must consume organic molecules.

• 5. Cyanobacteria were the first to use water instead of hydrogen sulfide

• Phylogeny• A. Archea

• 1. Methanogens produce methane from hydrogen gas and carbon dioxide- oxygen is poison to them

• 2.Halophiles live in saline places.• 3.Thermophiles like high heat

• B. Bacteria• 1. Make up the majority of prokaryotes

• III. Importance of prokaryotes• A. Decomposers- they return elements to the environment• B. Symbiosis- relationships _between organisms

– 1. Mutualism- Rhizobium and legumes, nitrogen is fixed for the plants to use

– 2. Commensalism- Bacteria living in the vagina keep it basic to prevent yeast growth

• C. Diseases• 1. Endotoxin- proteins on the prokaryote membranes

» Exotoxin- proteins secreted by prokaryotes, ex botulism toxin- 1 gram can kill 1 million people

• D. Research

Exotoxins

Tubeworms have no mouth, eyes, or stomach (“gut”). Their survival depends on a symbiotic relationship with the billions of

bacteria that live inside of them. These bacteria convert the chemicals that shoot out of the hydrothermal vents into food for the worm. This chemical- based food-making process is referred

to as chemosynthesis.

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Salmonella

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Lyme disease, or borreliosis, is an emerging infectious disease caused by bacteria from the genus Borrelia