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Bacteria 19-1 What are Bacteria? Bacteria are: • prokarytoic, meaning they do not store their DNA in a nucleus • unicellular • classified into two domains/kingdoms based on their cell walls and habitat Bacteria are classified into two domains/kingdoms a. Domain Archaea, Kingdom Archaebacteria 1. Cell wall: Does not contain the carbohydrate peptidoglycan, but it is still present 2. Habitat: Extreme environments (high salt, high heat, no oxygen, etc.) Deep sea vent Bacteria are classified into two domains/kingdoms b. Domain Bacteria, Kingdom Eubacteria 1. Cell wall: Contains the carbohydrate peptidoglycan 2. Habitat: All over the earth, in soil, on and inside organisms (including you) Two different kinds of eubacteria magnified 1000X Streptococcus and E. coli Please make sure you label the following: Parts of Bacteria 1. Plasma (cell) membrane- selectively permeable for exchange of nutrients and waste 2. Cytoplasm- jelly like fluid inside cell 3. Cell Wall- made of peptidoglycan in Eubacteria 4. DNA- free in cytoplasm but clustered in a “nucleoid region” Parts of Bacteria 5. Pili- small protein extensions used to anchor themselves OR sex pili aide in exchanging DNA 6. Flagella- whip-like tail for movement 7. Ribosomes- translate genetic material into proteins Classification: Scientists use several characteristics to classify Eubacteria. – Shape – Cell wall – Metabolism Classification: Shape There are three basic shapes of bacteria: 1. Coccus (cocci, pl.) -round shape, 2. Baccillus (bacilli, pl.)- rod shaped 3. Spirillum (spirilli, pl.)- corkscrew shaped More prefixes… • Staphylo- clump of grapes • Strepto- in a line • Diplo- two • What would this be? Classification: Cell wall • Cell Wall: Eubacteria are also identified by thickness of their cell wall. Scientists use a method called Gram staining to determine cell wall thickness. – Gram + : bacteria stains purple, meaning they have a thick cell wall of peptidoglycan – Gram - : bacteria stains light pink, meaning they have a thin wall of peptidoglycan Gram + or - ? Gram + or - ? How would we classify these bacteria? • • • Left? – streptobacillus, Gram + Center? – staphylococcus, Gram + Right? – bacillus, Gram - Classification: Metabolismnourishment • • Bacteria can also be classified by how they obtain energy and use it. They can be heterotrophs (must obtain their food/energy from another source) or autotrophs (can make their own food by capturing energy). There are two kinds of autotrophs: Classification: Metabolismnourishment 1. Chemoautotrophs- make their own food starting with energy from inorganic molecules like ammonia, hydrogen sulfide, sulfur, or nitrates 2. Photoautotrophs- make their own food using light energy 3. Chemoheterotrophs- consume food for energy and carbon 4. Photoheterotrophs- are photosynthetic, but must consume their carbon compounds Classification: Metabolismrespiration- using their food 1. Obligate aerobes- requires O2 supply, like Tuberculosis mycobacterium 2. Obligate anaerobes- cannot grow in presence of O2, like Clostridium botulinum 3. Facultative anaerobes- do not require O2 but are not harmed by its presence, can live anywhere like Escherichia coli. Reproduction 1.Bacteria reproduce asexually, through a process called binary fission, in which one cell splits into two. a. Binary fission includes three steps i. ii. iii. DNA replication cell growth Cytokinesis (division of cytoplasm) Binary fission 1. _____________ 2. _____________ 3. Cytokinesis_____ Reproduction b. All offspring are identical to the original bacterial cell. c. Binary fission is quick and can take as little as 20 minutes. d. Genetic variation in bacteria is due to: 1. Mutations 2. Small parts of DNA can be exchanged through sex pili, which are like little tunnels through which the DNA can pass from one cell to another- this is called conjugation. Reproduction • Spore formation happens when the environment is UNFAVORABLE for reproduction – They can stay dormant for months or even years – Ex: Anthrax Importance of Bacteria 1. Producers: Some are producers in food webs, capturing energy by photosynthesis. 2. Decomposers: When all organisms die, their organic matter must be returned to the soil for other organisms. Decomposers are involved in the cycles of matter (the carbon, nitrogen, and phosphorus cycles). Importance of Bacteria 3. Nitrogen fixers: Some bacteria live on the roots of trees and convert nitrogen into a form that plants can use called ammonia. This is a mutualistic symbiotic relationship between the plant and the bacteria. 4. Food production: Bacterial fermentation is used to make yogurt, sour cream, vinegar, buttermilk, and more. Importance of Bacteria: Human Uses 5. Human Health: E. coli bacteria living in our intestines use undigested food to produce vitamins K and B12 for us that we cannot make on our own. In return, we provide them with a warm environment. This is a mutualistic symbiotic relationship. Viruses 19-2 Viral Structure Viruses have a simple structure: 1.genetic material (DNA or RNA) 2.a protein coat called a capsid that surrounds the genetic material 3.Sometimes they have an envelope outside of the capsid (made of lipids and proteins). • Viruses are very small. If an average virus were the size of an average person, a bacterial cell would be the size of a dinosaur over ten stories tall. • http://learn.genetics.utah.edu/content/begi n/cells/scale/ Name tells you this virus infects bacteria Name tells you this virus causes influenza Are Viruses Living Things? * * Living things. . . 1. Are made of cells 2. Can reproduce 3. Based on a universal genetic code 4. Grow and develop 5. Obtain and use materials and energy 6. Respond to the environment 7. Maintain homeostasis 8. As a group, change over time Make sure you star your paper! Viral Characteristics Viruses only have the characteristics with stars. They are NOT considered to be living because: 1. 2. They use a host cell for energy They use a host cell for replication Viral Characteristics Viruses are considered parasites because they rely on a host and can destroy the host cells. Viruses are pathogens; a pathogen is something that can cause a disease or illness (could be a virus, bacterium, fungus, etc.). Virus Names Viruses are named for either: 1.the disease they cause (example: influenza virus causes influenza) or 2.the area they infect (example: rhinovirus infects the nose) Viral Infection of cells 1.Viruses cannot replicate on their own, they must hijack cells to make more virus. A viral infection of only one cell produces thousands of viruses. Viral Infection of cells 2. Viral infection is specific for only one cell type. a. Cells have receptors on the surface of their cell membranes that recognize products to take into a cell. b. Viruses mimic things to be let in, and trick the cell into taking them in. Cell surface receptors Viral Infection of cells 2.Viral infection is specific for only one cell type. a. Viruses have antigens (markers) on their surface. c. Only when the viral antigen binds to the cell receptor (fitting together like puzzle pieces) can a virus infect a cell. Viral antigens Which type of cell will be infected by the virus shown below? How do viruses infect cells? • Once inside the host cell, one of two different processes can occur: – Lytic cycle – Lysogenic cycle A. Lytic Cycle: Viral DNA enters a cell, reprograms the cell to makes copies of the virus, and causes the cell to burst releasing new viruses. B. Lysogenic cycle: A virus integrates its DNA into the DNA of the host cell, and the viral genetic information replicates along with the host cell DNA. Lysogenic infections may become lytic if the viral DNA leaves the host DNA. To lytic cycle From lysogenic cycle • Video Clip Activity: Cell, Virus, or Both? Contains nucleic acid as genetic material Activity: Cell, Virus, or Both? Can grow and develop Activity: Cell, Virus, or Both? Can only be replicated in a host Activity: Cell, Virus, or Both? Can reproduce on its own Activity: Cell, Virus, or Both? Obtain and use materials and energy Activity: Cell, Virus, or Both? Respond to the environment Activity: Cell, Virus, or Both? Maintain homeostasis Activity: Cell, Virus, or Both? Can contain DNA Activity: Cell, Virus, or Both? Which is smallest? Activity: Cell, Virus, or Both? Activity: Cell, Virus, or Both? DNA Viruses vs. RNA Viruses 1.DNA viruses do not mutate frequently because they utilize the host cell's DNA polymerase to make more copies of the viral DNA. Remember, DNA polymerase can proofread and correct errors (mutations) during DNA replication. That is why you only need a vaccine for a DNA virus once. Examples: smallpox, HPV (warts, cancers). DNA Viruses vs. RNA Viruses 2. RNA viruses have a high mutation rate because when the cell copies RNA for new viruses, the enzyme used cannot proofread and fix mutations. Examples: Influenza, common cold virus (rhinovirus). DNA Viruses vs. RNA Viruses a. Some RNA viruses use their RNA to make DNA which gets integrated into the host cell; called retroviruses. b. When retroviruses make a copy of the RNA as DNA, the DNA can integrate into host cell DNA causing a lysogenic infection. c. Example: Human Immunodeficiency Virus (HIV), Ebola virus Symptoms of Viral Infections Lytic Infections: If you have a lytic infection, you will have symptoms of the infection because your cells are being destroyed and your immune system is fighting the infection. Symptoms of Viral Infections Lysogenic Infections: You can have a viral infection and not know it if the infection is lysogenic. In this cause you will not show any symptoms of the infections. It is dormant.