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89 Cards in this Set
- Front
- Back
Virus
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Tiny infectious agents (smaller than bacteria - size of large protein)
Consists of: 1. Capsid 2. DNA or RNA genes Some surround themselves with a lipid-rich envelope All organisms experience viral infections Not considered organisms Reproduce with host's reproductive machinery (transfer of genetic information) Do not metabolize organic nutrients, use ATP from host In active form, not separated from external environment like cell wall or membrane Possess either DNA or RNA, not both Can be crystallized without losing ability to infect |
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Capsid
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Protein coat
Also know as head Contains nucleic acids DNA or RNA genes inside |
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Envelope
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Lipid-rich
Either borrowed from host cell or synthesized in host cell cytoplasm Contains virus-specific proteins |
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Virion
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Mature virus outside host cell
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Host
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Cell being infected
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Viral infection
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Begins when virus absorbs to a specific chemical receptor site on host
1. Landing 2. Attachment 3. Tail contraction 4. Penetration and injection Most viruses that infect eukaryotes are engulfed via endocytosis Once inside cell, 2 paths: 1. lysogenic infection 2. lytic infection |
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Chemical receptor
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Usually specific glycoprotein on host cell membrane
Virus cannot infect cell if specific receptor is not available |
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Bacteriophage
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Virus that infects bacteria
Made up of: 1. Capsid or head 2. Tail 3. Tail fiber Nucleic acid is injected through the tail after viral enzymes have digested a hole in the cell wall |
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Lytic infection
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Virus takes control of host's reproductive machinery and makes new viruses
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Eclipse period
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Brief period before first fully formed virion appears
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Latent period
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Period from infection to lysis (fill with new viruses until it bursts)
Encompasses the eclipse period |
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Virulent virus
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Virus following a lytic cycle
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Lysogenic infection
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Viral DNA is incorporated into host genome
If RNA, DNA is reverse transcribed from RNA and then incorporated into host genome When host cell replicates DNA, viral DNA is replicated as well Temperate virus - host may show no symptoms of infection |
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Reverse transcriptase
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Enzyme that reverse-transcribes RNA into DNA
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Dormant or Latent
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When viral DNA remains incorporated in host DNA - no symptoms
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Provirus
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Prophage if virus is in bacterium
Virus that is dormant or latent |
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Virulent
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When virus is not longer dormant or latent and becomes active
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Plus-strand RNA
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Virus that is unenveloped
Ex: common cold Plus-strand indicates that proteins can be directly translated from RNA |
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Retroviruses
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Virus with enveloped plus-strand RNA
Ex: HIV/AIDS Carries reverse-transcriptase enzyme to create DNA from RNA - then DNA is incorporated into host genome |
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Minus-strand RNA
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Virus with minus-strand RNA
Minus-strand RNA is complement to mRNA and must be transcribed to plus-RNA before being translated Ex: measles, rabies, flu |
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Types of Viruses:
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1. Plus-strand RNA
2. Retrovirus 3. Minus-strand RNA 4. Double-stranded RNA 4. Single and double-stranded DNA |
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Viroids
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Small rings of naked RNA without capsids
Only infect plants |
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Prions
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Naked proteins that infect animals
Capable of reproducing themselves, without DNA or RNA |
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Virus Lytic Life Cycle
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1. Uninfected cell
2. Virus absorbs the cell wall 3. Viral nucleic acid injected into cell 4. Replication of active virus 5. Assembly of new viruses 6. Lysis of cell 7. Virions |
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Virus Lysogenic Life Cycle
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1. Uninfected cell
2. Virus absorbs to cell wall 3. Viral nucleic acid injected into cell 4. Reduction of provirus 5. Viral DNA integrated into chromosome 6. Reproduction of lysogenic bacteria 7. Induction of of provirus to active virus 8. Replication of active virus 9. Assembly of new viruses 10. Lysis of cell 11. Virions |
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Vaccine
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1. Injection of antibodies
2. Injection of non-pathogenic virus with same capsid or envelope (allows for host immune system to create its own antibodies) |
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How to kill viruses:
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1. Antibodies to viral proteins (constantly mutating)
2. Cytotoxic T cells which destroy infected cell |
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Carrier population
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Makes it difficult to fight viral infections
Can infect more than one animal, some animals infected without symptoms |
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Prokaryotes
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Organisms without membrane bound nucleus
2 domains: 1. Bacteria 2. Archaea Single, circular double stranded molecule of DNA Contain a nucleoid No complex, membrane-bound organelles Contain RNA, small ribosomes (translating proteins), mesosomes (not necessarily), inclusion bodies, nucleoid, etc. |
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Archaea
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Much in common with eukaryotes and bacteria
Found in extreme environments (salty lake and boiling hot springs) Cell wall not made from peptidoglycan (unlike bacteria) |
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Fixing CO2
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Reducing CO2 and using carbon to create organic molecules
Process called Calvin Cycle Energy expensive |
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Autotrophs
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Organisms capable of using CO2 as their sole source of carbon
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Heterotrophs
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Organism that use preformed organic molecules as carbon source
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2 sources of Energy
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1. Light
2. Oxidation of organic or inorganic matter |
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Phototrophs
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Organisms that use light as energy source
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Chemotrophs
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Organisms that use oxidation of organic or inorganic matter as energy source
Only prokaryotes can acquire energy from inorganic source other than light |
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Nucleoid
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DNA, RNA and protein complex in prokaryotes
Forms a structure that is visible under light microscope Also called: chromatin body, nuclear region or nuclear body Not enclosed by membrane |
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2 types of bacteria
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1. cocci (round)
2. bacilli (rod shaped) 3. Spirilla (helically shaped, rigid) 4. Spirochetes (helically shaped, not rigid) |
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Plasma membrane
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phospholipid bilayer surrounding cytosol of prokaryotes
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Phospholipid
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composed of:
1. phosphate group (polar) 2. 2 fatty acid chains (nonpolar) 3. glycerol (3C backbone) amphipathic: having both polar and nonpolar portions - molecules spontaneously aggregate in aqueous solution, turning polar ends toward solution and nonpolar ends towards each other - making a spherical structure) |
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Micelle
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Spherical structure formed by amphipathic molecules in aqueous solution
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Membrane proteins
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1. Transporters
2. Receptors 3. Attachment sites 4. Enzymes Functional aspects of membranes |
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Integral or Intrinsic Proteins
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Amphipathic proteins that traverse membrane from inside of cell to outside of cell
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Peripheral or Extrinsic Proteins
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Proteins entirely on surface of membrane
Ionically bonded to integral proteins or polar group of lipid |
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Fluid Mosaic Model
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Model of membrane fluidity
Membrane is held together by intermolecular forces Membrane is fluid - its parts can move laterally but cannot separate Assymetrical layout of membrane proteins (mosaic aspect of membrane) Haponoids (steroid-like molecules in prokaryotes) or steroids (eukaryotes) reduce fluidity of membrane |
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Diffusion
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Movement of compound in high concentration to low concentration (for molecules without electric charge)
Occurs in direction of decreasing free energy or increasing universal entropy |
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Chemical concentration gradient
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Gradual change in concentration of compound over a distance
Series of vectors pointing toward lower concentration |
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Electrical gradient
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Movement of compound with charge
Points in direction that positively charged particle will tend to move (toward negative charge) |
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Electrochemical gradient
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Combination of electrical and chemical gradient for a specific compound
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Semipermeable
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Membrane slows but does not stop diffusion of compound
Affected by: 1. Size 2. Polarity The larger the molecule, the less permeable the membrane to that molecule The more polar a molecule, the less permeable the membrane to that molecule |
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Passive diffusion
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Diffusion of molecules through leakage channels across membrane due to random motion
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Transport or Carrier Proteins
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Designed to facilitate diffusion of specific molecules across the membrane
Molecules that are too large or too charged |
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Facilitated Diffusion
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Diffusion must occur down the electrochemical gradient of all compound involved
Many mechanisms used by transport proteins Ex: glucose Makes membrane selectively permeable - able to select between molecules of similar size and charge |
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Active transport
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Movement of compound against electrochemical gradient in order to concentrate nutrients
Requires expenditure of energy: 1. Direct expenditure of ATP 2. Using ATP to create an electrochemical gradient, using energy of electrochemical gradient to expel or acquire compound of interest (Secondary active transport) |
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Protoplast
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Bacterial plasma membrane and everything inside it
Not a complete bacterium Surrounded by bacterial envelope |
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Bacterial envelope
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Component of envelope, adjacent to plasma membrane is the cell wall
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Cell Wall
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Prevent protoplast from bursting
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Hypertonic
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Aqueous solution of cytosol contains more particles than surrounding aqueous solution
property of bacteria |
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Isotonic
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Cytosol contains same amount of particles as surrounding aqueous solution
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Hypotonic
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Cytosol contains less particles than surrounding aqueous solution
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Hydrostatic pressure
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Pressure created by cell wall filling with water
Equal to osmotic pressure when at equilibrium |
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Peptidoglycan
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Makes up cell wall
Archaea do not have Series of disaccharide polymer chains with amino acids (3 of which are not found in proteins) Form single molecular sac around bacterium More elastic than cellulose Porous - allows large molecules to pass through |
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Gram staining
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Classification of bacteria based on type of cell wall
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Gram-positive bacteria
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Thick peptidoglycan cell wall (4x thicker than plasma membrane) prevents gram stain from leaking out
Cells stain purple |
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Gram-negative bacteria
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Appear pink when stained
Thin peptidoglycan cell wall allows gram stain to wash off Have phospholipid bilayer (more permeable - allowing large molecules, like glucose, to pass through) outside cell wall |
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Gram-positive envelope
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1. Capsule
2. Peptidoglycan 3. Periplasmic space 4. Plasma membrane 5. Cytosol |
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Gram-negative envelope
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1. Capsule
2. Lipsaccharide layer 3. Outer membrane 4. Periplasmic space 5. Peptidoglycan 6. Periplasmic space 7. Plasma membrane 8. Cytosol |
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Bacterial Flagella
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Long, hollow, rigid, helical cylinders
Made from globular protein called flagellin Not same as eukaryotic flagella (made of microtubules) Rotate counterclockwise to propel bacterium in single direction If rotate clockwise, bacterium tumbles, allowing bacterium to change directions Uses energy from proton gradient (not ATP) |
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Flagellin
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Globular protein that makes flagella
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Genetic Recombination
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1. Conjugation
2. Transformation 3. Transduction Not mechanism of reproduction |
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Binary Fission
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Mechanism of asexual reproduction of bacterium
1. Circular DNA is replicated 2. Form 2 complete DNA double stranded circles 3. Cell divides, leaving one circular chromosome in each cell 2 daughter cells are genetically identical |
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Conjugation
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Type of genetic recombination
1 of bacterium requires a plasmid with gene coding for sex pilus Sex pilus connects 2 bacteria Passage of DNA is from cell containing sex pilus to cell cell that does not |
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Plasmids
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Small circles of DNA that exist and replicate independently of bacterial chromosome
Replicates differently than circular chromosome |
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Sex pilus
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Hollow, protein tube that connect 2 bacteria to allow passage of DNA
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F plasmid
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Fertility factor or F factor
1st plasmid to be described Bacterium with F plasmid = F+ Bacterium without F plasmid = F- |
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R plasmid
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Donates resistance to certain antibiotics
Conjugative plasmid |
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Transformation
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Process by which bacteria may incorporate DNA from external environment into genome
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Transduction
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Capsid of bacteriophage will mistakenly encapsulate a DNA fragment of host cell
When these virions infect new bacterium, they inject harmless bacterial DNA fragments instead of virulent viral DNA fragments |
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Vector
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Virus that mediates transduction
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Fungi
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Distinct kingdom of organisms with diversity
Eukaryotic heterotrophs Obtain food by absorption rather than ingestion Secrete digestive enzymes outside bodies and absorb products of digestion Most are saprophytic Most posses septa Fungal cell may contain 1 or more nuclei (mitosis takes place entirely within the nucleus) Consist of mycelium of hyphae Multicellular (exception Yeast) Lack centrioles |
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Saprophytic
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Live off dead organic matter
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Septa
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Cell walls of fungi
Made up of polysaccharide chitin Perforated to allow exchange of cytoplasm between cells (cytoplasmic streaming - allows for rapid growth) |
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Chitin
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Polysaccharide that makes up cell wall of fungi
More resistant to microbial attack than cellulose |
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Mycelium
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Tangle mass of hyphae in fungi during growth state
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Hyphae
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Multiple thread-like structures making up mycelium in fungi during growth state
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Haploid
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single copy of DNA
Predominates in fungi life cycle Growth stage of fungi Hyphae are haploid |
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Spores
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Haploid
Give rise to new mycelia in asexual reproduction Borne by air currents, water or animals |
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Budding
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Asexual reproduction in yeast
Also called cell fission Smaller cell pinches off from single parent cell |
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Sexual reproduction in fungi
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Between hyphae from 2 mycelia of different mating types (+ and -)
1. 2 hyphae grow towards one another 2. Touch 3. Form conjugation bridge 4. Tip of hyphae forms complete septum 5. Becomes gamete producing cell 6. Gametes fuse into zygote (diploid) Asexual reproduction occurs when conditions are good Sexual reproduction occurs when conditions are tough |