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Title: Biodiversity
Description: These notes go over biodiversity in terms of prokaryotes, protists, and fungi. These notes were taken for an introductory college biology course.
Description: These notes go over biodiversity in terms of prokaryotes, protists, and fungi. These notes were taken for an introductory college biology course.
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Biodiversity
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Evolution works via three mechanisms: natural selection, genetic drift, and migration
Macroevolution can lead to speciation, which can lead to behavioral/morphological
changes
Evolution has produced the all of life on Earth today
Systematics: study of how organisms are organized
o Often according to evolutionary relatedness
o Often using phylogenetics
All species have a scientific name, made up of the species and genus name
o Homo Sapiens: sapiens is species name and Homo is genus
How we classify things
o Eight levels of classification, each getting smaller and more specific
o Kingdom, phyla, class, order, family, genus, species
o There are actually many disagreements about how to classify organisms
▪ Disagreement on what type of data to use
▪ Hybridization
▪ Asexual organisms, such as bacteria
The beginning of life
o Earth is around 4
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4 billion years ago in the form of prokaryotic
microbes
Three domains: Bacteria, Archaea, and Eukarya
o Bacteria and Archaea are prokaryotes
▪ Single cellular organisms without membrane bound organelles that
reproduce asexually via binary fission
▪ Can live just about anywhere, and can be symbiotic with other organisms
▪ Very small, eukaryotes are 10-100x larger
▪ Extremely diverse --> you have about 500 bacterial species in your mouth
▪ Bacteria
• Relatively simple but efficient prokaryote
• Has a cell wall made of peptidoglycan (mix of carbs and protein)
• Very short generation time (1-3 hours)
• Can feed on organic molecules, chemicals, or sometimes do
photosynthesis
• Have a main chromosome, which is circular
• Each cell may also have additional plasmids
• Smaller circles of DNA
• May carry accessory genes
• Aid in metabolism
• Can also make a harmless bacteria deadly
• Can receive plasmids/DNA from other bacteria, viruses, or just
free-floating DNA
• These plasmids can confer resistance to antibiotics
Biodiversity
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Difficult to use biological species concept because no sexual
reproduction and no reproductive isolation
• Use cell shape and staining patterns to distinguish species
• Many species of bacteria live in the large intestine (gut flora)
• Produce vitamins and are a source of gas
• Many species are also a source of disease and sickness
• STD's, colds, tuberculosis, etc
▪ Archaea
• Single cellular prokaryotes that were once thought to be very similar
to bacteria
• Studies on their DNA and genes show them to be very different
• Extremophiles: archaea have evolved to live in conditions where most
organisms can't live
• Extreme temperature, acidity, harsh chemicals, etc
▪ Viruses
• All viruses contain a protein shell (capsid), DNA or RNA, a plasma
membrane, marker proteins
• Must infect a host to make copies of itself
• No agreement about whether or not viruses are alive
Eukarya
▪ Protists
• Membrane bound organelles and nuclei
• Can be single celled (most) or multicellular
• Larger size than prokaryotes
• Both sexual and asexual reproduction
• Very diverse, and first eukaryotes were protists
• Protists are not a natural grouping
• Natural groups include the common ancestor plus all of the
descendants of that common ancestor
• Basically includes all eukaryotes that were not fungi, plants, or
animals
• Three basic types that independently evolved
• Animal like protists
• Free moving
• Heterotrophs: can't make its own food
• Eats smaller prokaryotes or other protists
• Phagocytosis: cell eating
• Has enzymes to break down food and expel waste
• Plant like protists
• Autotrophs and use photosynthesis
• Can be unicellular (diatoms) or multicellular (algae)
• Exclusively live in water
• Usually the base of the marine food web
• Fungus like protists
Biodiversity
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Heterotrophs and decompose dead organic matter
Grows in colonies
Produces fruiting bodies that produces spores
Fungi
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Heterotrophs that get energy by breaking down dead organisms
Sessile: fungi do not move around
Have cell walls made of chitin (also used in insect exoskeletons)
Extremely diverse, but vastly understudied
Many take part in symbiotic/mutualistic relationships
• Mycorrhizae are fungi that live on plant roots
• Fungus gets sugars made from plants and the plants get
soil nutrients that only the fungus can access
• Lichen is a relationship between a fungus and a photosynthetic
green algae or bacteria
• Found on rocks and trees, and can make soil
The majority of infectious diseases are caused by bacteria, viruses,
protists, or fungi
• Often rely on transmission between organisms
• Resistance to medical treatment can evolve quickly
Structure
• Most individuals made up of hyphae
• Long strings of cells that contain the chemicals used to
break down organic matter
• Usually in the soil
Reproduction
• Can do both sexual and asexual reproduction
• Some produce structures used in reproduction
Yeast
• Unicellular and important to humans
• Alcohol and baking
• Used as a model organism to study genetics
Title: Biodiversity
Description: These notes go over biodiversity in terms of prokaryotes, protists, and fungi. These notes were taken for an introductory college biology course.
Description: These notes go over biodiversity in terms of prokaryotes, protists, and fungi. These notes were taken for an introductory college biology course.