LIFE 103 (Erik Arthun) Week 2 Notes
LIFE 103 (Erik Arthun) Week 2 Notes LIFE 103
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This 5 page Class Notes was uploaded by Lauren Caldwell on Friday February 5, 2016. The Class Notes belongs to LIFE 103 at Colorado State University taught by Erik Arthun, Tanya Dewey in Spring 2016. Since its upload, it has received 15 views. For similar materials see Macrobiology; Plants and Animals in Biology at Colorado State University.
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Date Created: 02/05/16
1/25 Monophyletic group o An ancestral species and all of its descendants Paraphyletic group o An ancestral species and some but not ALL of its descendants Polyphyletic group o An ancestral species and its descendants AND some… other cousins Prokaryotes: Masters of Adaptation o Prokaryotes can be in both the domains Archaea and Bacteria Archaea is in the genus Halobacterium (salt - bacteria) -> is also more closely related to animalia than plants, thus the domains are different o ATP used to actively pump potassium into the cell This is in order to create an isotonic solution (look right) Every lifeform on the planet is made of either Prokaryotes or Eukaryotes o Protists, fungi, animals, and plants are all eukaryotic cells o The domains bacteria and archaea are only prokaryotic cells Thus only single-celled organisms Can thrive anywhere: Places too: Acidic, salty, cold, hot There are more prokaryotes in a handful of fertile soil than the number of people who have ever lived Earth's first organisms were likely prokaryotes Prokaryotes o Most are microscopic o Huge numbers though (like the seagulls to human ratio at AV) o Most prokaryotic cells are .5-5 micrometers, as compared to the 10- 100 micrometers of many eukaryotic cells o Shapes Spheres (cocci) Rods (bacilli) Looks more like a horsepill than anything else Spirals Look more like flagella Why we know so little about these guys: o Its pretty difficult to study things that small o We learn best by culturing, but greater than 99% of bacteria and archaea are not culturable o We are starting to learn about uncultured diversity by studying DNA from different environments Structure Present in all bacteria: o "nucleoid" o Cytoplasm o Membrane (plasma) o Cell wall Not a plant cell wall o Ribosomes o Capsule o Flagella o Sex pilus Allows them to transfer DNA to another bacterium Prykaryotes do NOT have: Membrane-bound organelles Nucleus Diversity Can live in any pH Photosynthesize Can convert atmospheric N (ni2rogen) to ammonium o Can make what cant be used by plants into something that CAN be used by plants Can degrade any organic compounds (decomposes) Uses rust (iron oxide) or sulfate instead of O 2n respiration Can infect nearly any Eukaryote o Nearly half of all bacterial diseases are caused by these guys Can live at temperatures above 100 C (boiling) DNA o The prokaryotic genome has less DNA than the eukaryotic genome o Most of the genome consists of a circular chromosome o The chromosome is not surrounded by a membrane; it is located in the nucleoid region Cell surface structures o Nearly all porkaryotic cells have their cell walls, which maintains cell shape, protects the cell, and prevents it from bursting in a hypotonic environment Helps determine the shape of a bacterium Its like the tire that surrounds the inner tube on the bike (remember that one Sunday morning) Provides strong structural support against osmotic pressures Most contain peptidoglycan for rigidity Repeating chain of carbohydrates cross-linked by protein chains Target of many antibiotics? It actually disrupts the cell wall Inhibits the enzymes that MAKE peptidoglycan Cell wall lysis Usually okay for humans since we lack cell walls (unless you have a penicillin allergy) EX: Penicillins o Eukaryote cell walls are made of cellulose or chitin o Bacterial cell walls contain peptidoglycan, a network of sugar polymers cross-linked by polypeptides Peptidoglycan - sugar AND proteins Very rigid o Archaea contain polysaccharides and proteins but lack peptidoglycan Capsule o A sticky layer of either sugar or protein o surrounds and covers the prokaryote o Can protect the bacteria against an attack from the immune system Bacterial endospores o Many prokaryotes make endospores (inside-spores; within the cell) o Can remain alive and viable for centuries (up to millions of years) Certain cells, when they don’t have enough water/food to survive, they duplicate the DNA and protects it and goes into a stasis When the conditions change, the endospores can replicate once again EX: B. Anthracis, C. Tetani, C. Botulinum Cannot and willnot be killed through being frozen, radiation, boiling, etc Totally fine until there are more resources Motility o Taxis The ability to move towards or away form a stimulus Can move pretty freaking fast (gotta go fast) o Most motile bacteria propel themselves by flagella scattered about the surface or concentrated at one or both ends "Water follows salt/solute" (when in references to hypertonic solutions) Pink in the lagoons comes from red membrane proteins These are used to capture sunlight o Then used for ATP Can survive in an environment where metal would dissolve because it is too acidic Captain america of life 1/27 Reproduction Prokaryotes reproduce through binary fission (exponential growth) "two-split" o Can divide every 1-3 hours o Key features: Small Have short generation times Rapid division leads to lot of opportunity for mutations Bacterial reproduction o Binary fission o Asexual process o Cell enlarges, duplicates chromosome, and divides into two daughter cells Diverse nutritional and metabolic adaptations have lead to the evolution of prokaryotes o Can be categorized by how they obtain energy and carbon Phototrophs get energy from light Chemotrophs get energy from chemicals (humans) BOTH: use CO2 as a carbon source Autotrophs require CO2 as a carbon source (NOT nutritionally- dependent on other living things) Heterotrophs require an organic nutrient to make organic compounds (humans) Oxygen in metabolism o "burning" oxygen in cell metabolism releases the msot energy from food Some bacteria and archaea can use other oxidants Ex: Nitrate, Sulfate, oxidized iron Prokaryotes use o Obligate aerobes require O for 2ellular respiration o Obligate anaerobes are poisoned by O and use2fermentation or anaerobic respiration Facultative anaerobes an survive with or without O (EX: 2 muscle cells!) Causes for diversity o Small size o Rapid generation time (ex: some can reproduce within 20 minutes) o Endospores o Small, light spores are easily dispersed to new habitats o Horizontal gene transfer (genetic recombination) Movement of genes among individuals from different speicies (Ex: Mosquito carrying horse blood) Genetic recombination -> combining DNA from two sources Usually involves Plasmids or small pieces of DNA Plasmids can replicate independently from the main chromosome Prokaryotic DNA is best for this - can be brought together by 3 ways Transformation Gathering of "naked DNA fragments" DNA binding proteins grab DNA floating around Like the lab in 102 Transduction Viruses -> bacteriophages - remember the lysing of cells? Conjugation Transfer of DNA during bacterial sex Directly form one bacterium to another Usually between members of the same species DNA transfer is a ONE WAY STREET here A donor cell attaches to a recipient by a pilus, pulls it closer, and transfer DNA Pilus - hollow tube DNA piece called the F factor is required to produce pili Overuse and missuse of antibiotics is leading these guys to developing resistance Archaea and Bacteria Archaea - the extremophiles Bacteria Usually grows in limited conditions includes majority of prokaryotes that we Hyper-saline (VERY salty know of conditions) o Halophiles Very high temps (up to 121 C) o Thermophiles Anoxic (no oxygen) Archaeal ex: Methanogens Live in swamps and marshes o Strict anaerobes Again, poisioned by O 2 o Exhale methane into the environment Pathogenic Bacteria Pathogens -> causes disease, eats at the host Bacteria cause about half of all human disease o Also important for humans Ex: lyme disease Pathogen example: Yersinia Pestis o Causes Bubonic Plague Killed 1/3 people living in Europe o Disease spread by fleas o Infection most common in rodents - can spread to humans
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