Biology 103 Week 2 Notes
Biology 103 Week 2 Notes BIO 103-002
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This 7 page Class Notes was uploaded by Lucas Kinsey on Monday September 12, 2016. The Class Notes belongs to BIO 103-002 at George Mason University taught by Gwendolyne Fondufe in Fall 2016. Since its upload, it has received 99 views. For similar materials see Introductory Biology I in Biology at George Mason University.
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Date Created: 09/12/16
Lucas Kinsey Biology 103 George Mason University Biology 103 Week 2 notes Chapter 14 Microevolution: Changes in the gene pool of a population from one generation to the next Macroevolution: The broad pattern of changes in life on Earth Speciation: The process by which one species splits into two or more species ** We as humans are homeo sapiens Reproductive Isolation: the prevention of genetic exchange and the maintenance of boundries between species Different Perspectives for Classifying a species: Biological Species concept: o Defines species as a group of populations who’s members have the potential to interbreed in nature and produce fertile offspring o Problems with this perspective include: No way to tell if fossils of organisms were able to interbreed Useless for classifying asexual organisms Morphological Species Concept: o Classifying species based on phenotypic traits Phenotypic: Seeable, physical traits o Over 1.8 million species have been identified with this perspective o Pros and Cons of this Perspective: Pros: Can be applied to classify fossil species and asexual organisms Cons: relies to much on subjective data Ecological Species Concept: o Classifies species depending on the environment they live in or their behavior in regards to other organisms Phylogenetic Species Concept: o Defines a species as the smallest group of individuals with a common ancestor Reproductive barriers that keep species separate: Prezygotic Barriers (Before Sex with other species Barriers) o Habitat: Lack of opportunities to find a mate o Temporal: Breeding occurs during different seasons o Behavioral: Failure to send or receive appropriate mating signals o Gametic: Molecular incompatibility of sperm and egg Postzygotic Barriers (After Sex with other species Barriers) o Reduced Hybrid Viability: getting unfavorable genes and not being able to survive o Reduced Hybrid Fertility: Not being able to have offspring o Hybrid Breakdown: Hybrid has good genes to keep it alive but offspring has insefficient genes Allopatric Speciation: When a geographical barrier isolates a species (ex: an island, two separate lakes, ect….) Speciation only occurs when the gene pool undergoes changes that establish reproductive barriers Sympatric Speciation: When a new species arises within the same geographic area as its parent Species - Can happen when accidents in cell reproduction result in extra chromosomes o These are called polypoid (their cells have more than two complete sets of chromosomes) o Most polypoids happen from the hybridization of two species o Estimates say 80% of plant species are a result of polypoid speciation in the past o New polypoids can be generated in a laboratory by using chemicals that induce meiotic and mitotic cell division errors ( ex: genetically engineered food) Adaptive radiation: The evolution of many diverse species from a common ancestor - EX: Darwin’s Finches Sexual Selection: certain traits allow for more successful mating than other traits Chapter 15 Earliest Evidence of life traces back 3.5 billion years Radiometric Dating: finding out the age of something by measuring its radioactive isotopes 2 Major Mass Extinctions: 1. Permian Period: a. Volcanic eruptions in present day Siberia led to the decrease in oxygen and increase in carbon dioxide in the atmosphere that killed off 96% of marine life and rose the global temperature 6 degrees Celsius 2. Cretaceous Period: a. A meteor hit Earth and caused a massive cloud that enveloped most of the Earth, killing off the Dinosaurs ** Adaptive Radiation usually follows after a mass extinction Homeotic genes: the “master control” genes - These changes usually lead to a drastic change in body for - Ex: legs evolving off of a snake Changes in the forms of organisms often are caused by mutations that affect the development and regulation of genes Exaptaions: structures in an organism that evolve for one context but are co- opted for another - These changes can lead to evolutionary trends, such as feet on animals, or feathers on birds Phylogeny: The evolutionary of a species or a group of species Convergent Evolution: Species from different evolutionary branches may come to resemble one one another if they grow in a similar environment - Analogy: A similarity in a convergent evolution Systematics: a discipline of biology that focuses on classifying organisms based on their evolutionary history A phylogenic tree often depict hypotheses about the evolutionary history of a species A Phylogenic tree of hierarchical classification Domain Kingdom Phylum Class Ordery Genus Species *A species gets its name by combining the genus and species names Ex: Common name: Cat o Family: Felidae Genus: Felis Species: Catus o Scientific name: Felis Catus Taxon: Each taxonomic unit at any level Clade: a group of species that includes an ancestral species and all its decendants Molecular Systematics: Uses DNA or other molecules to infer relatedness - Molecular Clock: a concept that estimates the time required for an evolutionary change Chapter 16 Prokaryotes are found everywhere there is life, including on multicellular organisms Pathogens: Disease causing bacterial agents - Harmless or beneficial prokaryotes are more common that harmful ones Microbiota: the community of microorganisms that live in and on our bodies - Guard against pathogens - Clean our skil by decomposing dead skin cells Prokaryotes Archaea Bacteria 3 Common Prokaryotic Cell Shapes: 1. Cocci: Spherical cells and occur sometimes in chains 2. Bacilli: Rod shaped and occur singly 3. Spirochetes: Spiral shaped cells Nearly all prokaryotes have a cell wall Gram Stain: A way to distinguish two types of cell walls in bacteria - Gram-Negative walls are complex with and outer membrane with lipids bonded to carbohydrates o Often are more dangerous because of toxic lipid membrane - Gram-Positive walls are simple and made up of peptidoglycan, a polymer of sugars cross-linked by short polypetides Flagella: “Legs” on a bacteria or archaea that enable the cell to move Fimbriae: Hair-like projections that allow some prokaryotes to stick to surfaces Prokaryotes can adapt rapidly to changes in the environment because they can reproduce quickly via binary fission - Every time a cell replicates, tiny mutations occur, causing a population to be able to adapt quickly to an environment Prokaryotes have unparalleled nutritional diversity, being able to gather nutrients in a multitude of ways - Can have 2 sources of energy: o Sunlight (not chloroplasts, but thylakoid membranes) o Chemicals - Need a source of organic or inorganic carbon Energy Source Sunlight Chemicals CO_2 Photoautotrophs Chemoautotroph s Carbon Source Photoheterotrophs Chemoheterotrophs Organic Compounds Bioremediation: the use of organisms to reduce pollution Archaea thrive in extreme environments: 1. Extreme Halophiles: thrive in salty places 2. Extreme Thermophiles: Thrive in hot places 3. Methanogens: Thrive in places with no oxygen Symbiosis: A close association between organisms of two or more species Cyanobacteria: only group of prokaryotes with plantlike oxygen-generating photosynthesis Chlamydias: Live in host eukaryotic cells Spirochetes: Helical bacteria that spiral through their environment Exotoxins: Proteins that bacteria emit into the environment (poisons) Endotoxins: Lipid Components of the outer membrane of from negative bacteria that are released when the cell dies Protists: a diverse collection of mostly unicellular eukaryotes - Algae = uses photosynthesis - Protozoans = are heterotrophs - Parasites = have a host cell - Mixotrophs = Use photosynthesis and heterotrophy *Most protists are aquatic 3 Clades that Make Up Protists: 1. Stramenopila a. Ex: Diatoms, Brown Algae, Water Molds 2. Alveolata a. Dinoflagellates, Ciliates 3. Rhizaria a. Amoebas, Foraminiferans, Radiolarians