Week 6 Notes
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This 9 page Class Notes was uploaded by Kaeli on Monday September 19, 2016. The Class Notes belongs to BIOL 102 001 at University of South Carolina taught by Mihaly Czako in Fall 2016. Since its upload, it has received 5 views.
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Date Created: 09/19/16
Chapter 26 Notes Prokaryotes o Structure No nuclear membrane Most are very small Very populous Common shapes spheres rods and spirals Surface structures that stick Exhibit taxis Move relative to a stimulus Flagella are a common structure o Not analogous o Made of different compounds o Divided into Bacteria and Archaea Unicellular o Likely first life o Can create endospores Survive harsh conditions for centuries o Have circular, simpler DNA A single circular chromosome Nucleoid region Smaller rings called plasmids (Bacteria) o Reproduction Binary fission 1 minute 3 hours Not sexual, no recombination in a meiotic sense Genetic diversity Rapid reproduction Mutation Genetic recombination o DNA moves between two cells via transformation, transduction, and conjugation o Transformation: uptake of DNA from environment o Transduction: movement of genes by bacteriophages (viruses) o Conjugation: Similar to sexual reproduction, one cell attaches to another by a pilus, pulls it closer and transfers DNA The presence of a pilus requires a gene for it Called F factor or F plasmid Occasionally part of the chromosome R plasmids carry antibiotic resistance o Metabolic diversity Photoautotrophs Make ATP from light Chemoautotrophs Extract energy from harsh chemicals Photoheterotrophy Light and others Chemoheterotrophy Chemicals and others Oxygen Obligate aerobes o Require O2 Obligate anaerobes o Poisoned by oxygen o Use fermentation Facultative anaerobes o With or without O2 Nitrogen Fixation N2> NH3 (ammonia) o Prokaryotic diversity Some plants have an organ specifically for nitrogen fixing prokaryotes Keep oxygen out Rhizobium Handful of soil may contain 10,000 species of prokaryotes Horizontal gene transfer obscures root of tree of life Agrobacterium produces tumors in plants and is used in genetic engineering Transfers genes into plants o Interdomain transfer o Without prokaryotes, prospects for any other life would be dim. Chemical recycling Symbiotic relationships Bacteria only o Have cell wall (ONLY Bacteria) Made of peptidoglycan (vs cellulose or chitin) Grampositive bacteria have simpler walls with a large amount of peptidoglycan Gramnegative have less peptidoglycan and an outer membrane that can be negative (added lipopolysaccharide) More likely to be antibiotic resistant A protein layer called a capsule covers many prokaryotes o Some have folds in membrane that serve a function Still NOT organelles Archaea o Similar to both Eukarya and Bacteria Closer to Eukarya More shared characteristics o Severe conditions Methanogens Produce methane Poisoned by O2 Halophiles High salt content Thermophiles High temperature Symbiosis o Organisms have a relationship o Larger host o Smaller symbiont o Prokaryotes commonly form symbiotic relationships o Types of relationships Mutualism Both benefit Most bacteria Examples: Chemoautotrophic bacteria in hydrothermal vents are the primary producers, others live off of them; intestinal bacteria Commensalism One benefits, one neutral Parasitism Symbiont harms the host Pathogens o Parasite that may be fatal Exotoxins Secreted Cause disease even if the producer is not present Endotoxins Released when bacteria die Outer membrane of Gramnegative bacteria Prokaryotes in research o E. coli is used in gene cloning o Bacteria can be used to make plastics o Bioremediation Removing harmful substances from environment o Biogas Natural ethanol Chapter 28 Notes Protists Protist o Informal name for mostly unicellular eukaryotes Not all unicellular o Polyphyletic group o Greater diversity than other eukaryotes Energy Photoautotrophs Heterotrophs Mixotrophs Reproduction Sexual or asexual Meiosis or fertilization o Protists’ categorization is everchanging Endosymbiosis o The symbiont lives inside the host Mitochondria Chloroplast o Secondary endosymbiosis Inception Endosymbiotic organism is engulfed Smallest organism still has a nucleus Example: Algae were engulfed by other cells Excavata o Has a cytoskeleton o Some have a feeding groove SAR clade o Controversial of the supergroups o Apicomplexans (Malaria) Parasites Sexual and asexual Plasmodium causes malaria Requires both mosquitos and humans to complete its life cycle Kills 900,000 people per year o Diatoms Two part wall of silicon dioxide A lot of phytoplankton Sink to the ocean floor when they die Creates oil Contributes to sediments (diatomaceous earth) o Brown algae (kelp) Most are multicellular Most are marine “Seaweeds” Largest and most complex algae Structures similar to plants (analogous) Blade leaves Stipe stem Holdfast roots Archaeplastida o Red algae Usually ulticellular Most abundant in costal tropics o Green algae Paraphyletic group Charophytes Closely related to land plants Chlorophytes formed by… Formation of colonies Formation of multicellular bodies Repeated division of nuclei o Land plants Unikonta o Amoebas Closer to fungi than animals Entamoebas Parasites of vertebrates Importance o Diverse habitats o Play two key roles Symbionts Some benefit their hosts Example: Wooddigesting protists in the bowels of termites Producers o Understanding parasitic protists is crucial Potato blight caused the Irish potato famine Chapter 29 Notes Plant Diversity I First land organisms were likely cyanobacteria and protists 1.2 billion years ago o 500 million years ago small plants, fungi, and animals colonized Plants o 290,000 species Very diverse o Land plants have terrestrial ancestors o Photosynthetic protists are not plants Charophytes are the closest relatives o Provide oxygen Most food eaten Evidence o Shared traits with charophytes o Cellulose synthesizing proteins o Flagellated sperm o Formation of phragmoplast o Sporopollenin Polymer that prevents zygotes from drying out Allowed colonization of land Sporopollenin is very durable Differences from relatives o Alternation of generations Alternate between reproductive stages Gametophyte Haploid Produces by mitosis Fusion produces sporophytes Produces haploid spores by meiosis o Multicellular, dependent embryos Diploid embryo Retained within the tissue of the female gametophyte Placental cells transfer nutrients Land plants are called embryophytes because of this o Walled spores Produced in sporangia Diploid cells called sporophytes undergo meiosis Haploid spores o Multicellular gametangia Wall around gametes Female gametangia called archegonia produce eggs Male gametangia called antheridia produce and release sperm o Apical meristems Various tissues develop Continual growth in their apical meristems Stem cells produce tissues Found in tip of root and tip of shoot o More derived traits Cuticle Waxy covering of the epidermis Stomata Opening between cells Mycorrhizae Symbiotic relationships between plants and fungi May have helped plants without roots to get nutrients o Some land plants have vascular tissue Call the ones that do vascular plants Seedless vascular plants were the first ones to grow tall Vascular plants have life cycles dominated by sporophytes o Seed plants Heterosporous Heterosporous species produce… Mega spores o Female gametophytes Micro spores o Male gametophytes Chapter 30 Notes Plant Diversity II Derived traits of seed plants o Reduced gametophytes Gametophytes are protected by the sporophyte Dependent gametophytes Cone bearing plants Seeds develop in cone Called gymnosperm Flowering plants Called angiosperm o Heterospory Male and Female spores o Ovules Gymnosperm Type of egg o Pollen Water unnecessary for fertilization o Seeds Survive better than unprotected spores Embryo and nutrients surrounded by protective coat Disperse over wide distances Called Gymnosperm or angiosperm
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