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Chapter 19. Bacteria & Viruses. Bacteria. Microscopic life covers nearly every square centimeter of Earth. All bacteria are prokaryotes. Classifying Prokaryotes Prokaryotes are identified by their size, shape, the way they move, the way they obtain energy.
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Chapter 19 Bacteria & Viruses
Bacteria • Microscopic life covers nearly every square centimeter of Earth. • All bacteria are prokaryotes. • Classifying Prokaryotes • Prokaryotes are identified by their size, shape, the way they move, the way they obtain energy. • Prokaryotes are placed into two kingdoms • Eubacteria: Larger of the two kingdoms, very diverse, live everywhere. • Typical eubacteria lives in the human intestines (ex. E.Coli) • Archaebacteria: Similar to eukaryotes, live in harsh environments.
Identifying Prokaryotes • Shape: Three different shapes • Bacilli- Rod shaped • Cocci- Spherical shaped • Spirilla- Spiral/corkscrew shaped • Cell Wall: Two different types of cell walls • Thin walls- Peptidoglycan layers • Thick walls-Lipid layers • Gram Staining: Methods used to identify wall type • Gram Positive: Identifies thicker, walls stain turns dark violet. • Gram Negative: Identifies thinner, walls stain turns pink or light red.
Identifying Prokaryotes Cont… • Movement: If they move & how they move. • Propelled by flagella (whip-like structure). • Lash, snake, or spiral forward. • Metabolism: The way the organism obtains and uses energy. • Heterotroph- Those that can not make their own food. • Chemoheterotrophs: Takes in organic material for food & carbon • Photoheterotrophs: Carry out photosynthesis and in take organic material for carbon. • Autotroph- Those that are capable of making their own food. • Photoautotrophs: Use light to convert CO2 and H2O into carbon compounds. • Chemoautotrophs: Do not need light to convert CO2 and H2O in carbon compounds.
Energy • Obligate aerobes: Require oxygen to live • Obligate anaerobes: Can not live in the presence of oxygen, in fact in some cases oxygen can kill these organisms. • Facultative anaerobes: Can function in different ways depending on their environment.
Growth & Reproduction of Prokaryotes • Bacteria can reproduce at astonishing rates, some reproduce every 20 minutes. • Types of Reproduction: • Binary Fission-Prokaryotes copies DNA, divides in half and produces two identical cells (asexual). • Conjugation-Two prokaryotic cells exchange genetic material to reproduce (sexual). • Spore Formation- When conditions are right prokaryotes can produce spores which can later when conditions are right will germinate and become bacteria.
Importance of Bacteria • Decomposer • Breaking down of dead or decaying organisms. • Nitrogen Fixer • Converts nitrogen gas into a form that can be usable by plants. • Human Uses • Industry • Technology • Synthesizing vitamins • Genetic Engineering • Oil Spills
Viruses • Viruses are particles of nucleic acid, protein, and in some cases lipids. • Typically viruses have a D.N.A. core and a protein coat • Capsid: The protein coat of the virus
Viral Infection • Lytic Infection: A virus enters a cell , makes copies of itself and then causes the cell to bust and release the copies it made of the virus. • Lysogenic Infection: A virus integrates its D.N.A. into the D.N.A. of the host cell, and the viral genetic information replicates along with the host cell’s D.N.A.
Viruses • Retroviruses: A virus that infects a cell and then uses it’s R.N.A. to make copies of it’s D.N.A. and then that D.N.A. is inserted into the host cells D.N.A. • Called retro because it goes from R.N.A.D.N.A. the opposite of other viruses. • Can lay dormant in the host cell for long period of time. • Some cancers are cause by retroviruses as well as H.I.V. the virus that causes A.I.D.S.
Diseases Caused by Bacteria • Bacteria in Humans: • Some bacteria infect the body then damage tissues and cells by breaking them down for food • Some Bacteria release toxins that interfere with normal cell activities. • We use Vaccines & Antibiotics to prevent and or treat bacterial infections. • Bacteria in Animals: • Many bacteria can affect both humans and animals.
Controlling Bacteria • There are many ways to control bacterial growth • Sterilization- Killing bacteria using heat • Disinfectants- Killing bacteria using chemicals • Food Processing
Diseases Caused by Viruses • Viral Disease in Humans: • Viruses disrupt the human body’s equilibrium • Many viruses infect and kill cells • Can’t be treated with antibiotics but can be vaccinated for. (some viruses eliminated by vaccines) • Viral Disease in Plants & Animals: • Viruses infect plants & animals very similarly to the way they infect humans, but in many cases carry be more severe and even can cause cancer.
