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Chapter 19 Bacteria and Viruses Notes.notebook April 06, 2016 Chapter 19 Bacteria and Viruses Section 1 Bacteria Key Concepts How do the two groups of prokaryotes differ? What factors are used to identify prokaryotes? What is the importance of bacteria? http://www.ted.com/talks/bonnie_bassler_on_how_bacteria_communicate?language=en Bacteria Prokaryotes lacks a nucleus and membrane bound organelles Microscopic Range in size from 15 micrometer 1 meter stick is cut into a million pieces for 1 micrometer or 10,000 pieces for a centimeter Largest bacteria is 500 micrometer long Kingdom Only one kingdom Monera until recently now 2 Eubacteria Larger Kingdom Live everywhere Cell Wall contain Peptidogylcan a carb Cell Membrane Archaebacteria Chemically different from Eubacteria Cell Wall but lack Peptidogylcan Different Cell Membrane Lipids Live everywhere even harsh conditions extreme heat, gas, salt water, fresh water, thick mud, Identifying Prokaryotes shape, chemical nature of their cell walls, their movement, how they obtain energy Shape Bacilli Bacilli plural Bacillus singular Rod Shaped Cocci Cocci plural Coccus singular Spherical Shaped Spirilla Spirilla plural Spirillum singular Spiral Shaped Cell Wall two different types use a Gram stain to tell difference Peptidoglycans in cell wall hold stain Grampositive Stain is washed out due to thin Peptidoglycan layer Gramnegative Grampositive Rodshaped Violet stained cocci Grampositive Gramnegative Rod Shaped Unstained Pink/Red Gramnegative Movement Identified by whether they move and how they move Flagella Multiple directions snake, or spiral forward Some move across a layer of slime they secrete Obtain Energy Most are heterotrophs: Chemoheterotrophs / Photoheterotrophs Chemoheterotrophs Chemoheterotrophs are unable to synthesize their own organic molecules. Instead, these organisms must ingest carbon molecules, such as carbohydrates and lipids, synthesized by other organisms. They do, however, still obtain energy from the oxidation of inorganic molecules. Chemoheterotrophs are only able to thrive in environments that are capable of sustaining other forms of life due to their dependence on these organisms for carbon sources. Photoheterotrophs Use sunlight for energy Must take in organic compounds as a carbon source. Can not use CO2 as their only carbon source. Autotrophs Chemoautotrophs Make organic molecules from CO2. Do not require light as a source of energy because they use chemical rxns. Photoautotrophs Use sunlight to convert CO2 and H2O to carbon compound and O2. Releasing Energy All bacteria need energy. How they get energy depends on the bacteria. Some need oxygen and some do not. Some it doesn't matter. It does this through cellular respiration and fermentation. Which way requires oxygen to make energy? And which way does not? Obligate aerobes obligate = required require oxygen Obligate anaerobes do not require oxygen and may be killed by it Facultative anaerobes does not matter, will do cellular respiration if oxygen and will do fermentation without oxygen Growth and Reproduction Conditions need to favorable for bacteria to grow and reproduce. Even though bacteria can develop in a variety of conditions from the Arctic to hot springs, its optimal growth is between 40o to 140o. Look on page 475 for examples. Binary Fission Asexual Bacteria grow until it doubles in size then divides Forms 2 identical daughter cells no exchange of DNA Conjugation Bridge forms between to cells and an exchange of DNA occurs Increases genetic diversity in populations Does not increase population of bacteria Why is this not considered a type of sexual reproduction? Spore Formation If conditions are not right, many bacteria will form a spore that protects the bacteria. One method of survival. Endospore thick wall that surrounds and protects Why are bacteria important? Decomposers break down dead matter and recycle nutrients to soil, water and air break down sewage so we can recycle the water, nitrogen and CO2 Nitrogen Fixers Nitrogen Fixation converting nitrogen gas into ammonia or other nitrogen compounds humans need nitrogen to make proteins, but we can not get it from the air but we get it by eating plants and animals that have eaten plants Human Uses of Bacteria oil spills remove waste products and poisons from water synthesize drugs and chemicals through genetic engineering food medical uses vitamins Feb 58:59 AM 1 Chapter 19 Bacteria and Viruses Notes.notebook Section 2 April 06, 2016 Viruses Key Concepts What is the structure of a virus? How do viruses cause infection? Look at Figure 199. Page 479 Virus Structures Look for Differences/Similarities in the different viruses. Differences Similarities What is a Virus? Virus = poison Nonliving Not made of cells Composed of DNA or RNA cells only have DNA Protein Coat surrounds genetic material = Capsid Many Shapes and Sizes Reproduce ONLY by infecting living cells 1. Surface Proteins bind with receptors on cells and trick the cell into letting the virus inside. Virus cells are specific to the cells they infect. Plant viruses infect plant cells and animal viruses infect animal cells. Bacteriophages infect bacteria cells 2. Once inside the cell the virus genetic material takes over and the cell begins to replicate the virus genetic material. 3. Host cell may or may not be destroyed right away. http://www.wimp.com/virusinvades/ Once inside two processes may occur Viral Infection Lytic Infection Overview Virus enters cell, causes cell to make copies of its genetic material and proteins, then the cell is destroyed Steps 1. First, the bacteriophage attaches to the bacterium's protein coat. 2. The bacteriophage then injects its DNA into the bacterium. 3. The bacteriophage takes over the bacterium's metabolism causing synthesis of new bacteriophage proteins and nucleic acids. 4. Bacteriophage proteins and nucleic acids assemble into complete bacteriophage. 5. Bacteriophage enzyme lyses the bacterium's cell wall, which releases new bacteriophage that attack other cells. Lysogenic Infection page 481 Virus enters cell, DNA incorporates itself into the DNA of the host cell (Prophage), then the new DNA is replicated, the host cell is not destroyed immediately Virus will lay dormant until a trigger stimulates prophage to remove itself and begin synthesis of the DNA and start the lytic cycle. Retroviruses Contain RNA Infect and produce a copy of the DNA which is then inserted into the cells DNA Retroviruses contain RNA for their genetic information when it enters cell, they produce a DNA copy of their RNA which acts as a prophage, after a signal is give to produce the DNA the host cell is destroyed responsible for some cancer cells Viruses and Living Cells viruses can be a parasite must infect a living cell to grow and reproduce viruses smaller than the smallest cell Look at Figure 1911 Compare Viruses and Cells Feb 1910:53 AM 2 Chapter 19 Bacteria and Viruses Notes.notebook April 06, 2016 https://www.youtube.com/watch?v=eMrFV2rnHlo Mar 211:32 AM 3
