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Viruses - Coggle Diagram

- - - - The lytic cycle produces new phages and lyses the host’s cell wall, releasing the progeny viruses
        
        A phage that reproduces only by the lytic cycle is called a virulent phage
    - - replicates the phage genome without destroying the host
        
        Phages that use both the lytic and lysogenic cycles are called temperate phages
  - - - An RNA or DNA genome, either single-stranded or double-stranded
        
        The presence or absence of a membranous envelope
  - - - The viral DNA that is integrated into the host genome is called a provirus
        
        vaccine is a harmless derivative of a pathogen that stimulates the immune system to mount defenses against the harmful pathogen
        
        A global epidemic is called a epidemic
- - - - Scientists use the Gram stain to classify bacteria by cell wall composition
        
        Gram-positive: bacteria have simpler walls with a large amount of peptidoglycan
        
        gramnegative bacteria have less peptidoglycan and are more complex with an outer membrane that contains lipopolysaccharides
        
        The cell wall of many prokaryotes is surrounded by a sticky layer of polysaccharide or protein. This layer is called a capsule if it is dense and well-defined
        
        Some bacteria form metabolically inactive endospores when water or nutrients are lacking
    - - Pili (or sex pili) ) are longer than fimbriae and function to pull cells together enabling the exchange of DNA
        
        Motility
        
        About half of all prokaryotes exhibit taxis, , the ability to move toward or away from a stimulus.
  - - - In transformation, the genotype and possibly phenotype of a prokaryotic cell are altered by the uptake of foreign DNA from its surroundings.
        
        transduction, phages (short for “bacteriophages,” the viruses that infect bacteria) carry prokaryotic genes from one host cell to another.
    - - is the process through which DNA is transferred between two prokaryotic cells
    - - Cells containing the F plasmid function
        as DNA donors.
    - - R
        plasmids, plasmids that carry resistance genes
    - - Obligate aerobes
        An organism that requires oxygen for cellular respiration and cannot live without it.
        
        anaerobic respiration
        A catabolic pathway in which inorganic molecules other than oxygen accept electrons at the “downhill” end of electron transport chains
        
        Nitrogen Metabolism
        
        nitrogen fixation
        The conversion of atmospheric nitrogen (N subscript 2) to ammonia (NH subscript 3) Biological nitrogen fixation is carried out by certain prokaryotes, some of which have mutualistic relationships with plants.
        
        heterocysts
        A specialized cell that engages in nitrogen fixation in some filamentous cyanobacteria; also called a heterocyte.
  - - - Extreme halophiles
        An organism that lives in a highly saline environment, such as the Great Salt Lake or the Dead Sea.
        
        Extreme thermophiles
        An organism that thrives in hot environments (often 60 to 80 degrees C or hotter).
        
        methanogens
        An organism that produces methane as a waste product of the way it obtains energy. All known methanogens are in domain Archaea.
  - - - symbiosis
        An ecological relationship between organisms of two different species that live together in direct and intimate contact.
        
        host
        The larger participant in a symbiotic relationship, often providing a home and food source for the smaller symbiont.
        
        symbiont
        The smaller participant in a symbiotic relationship, living in or on the host.
        
        mutualism
        A positive-positive ecological interaction that benefits individuals of both interacting species.
        
        commensalism
        A positive-neutral ecological interaction that benefits the individuals of one species but neither harms nor helps the individuals of the other species.
        
        parasitism
        A positive-negative ecological interaction in which one organism, the parasite, benefits by feeding upon another organism, the host, which is harmed; some parasites live within the host (feeding on its tissues), while others feed on the host’s external surface.
        
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    - - Endotoxins
        A toxic component of the outer membrane of certain gram-negative bacteria that is released only when the bacteria die.
        
        Exotoxins
        A toxic protein that is secreted by a prokaryote or other pathogen and that produces specific symptoms, even if the pathogen is no longer present.
- - - - Viral Genomes
        
        Viral genomes may consist of either
        
        – double- or single-stranded DNA or
        
        – double- or single-stranded RNA
        
        The genome is either a single linear or circular
        molecule of the nucleic acid
        
        Capsids and Envelopes
        
        viral envelopes, which are derived from the membranes of the host cell, contain host cell phospholipids and membrane proteins.