Microbiology

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Author:
hellosleepy
ID:
158823
Filename:
Microbiology
Updated:
2012-07-19 11:49:09
Tags:
MCAT
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Description:
MCAT biology
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  1. Why are viruses so difficult to treat?
    They are rapidly mutating...those sneaks.
  2. Why is a virus considered to be non-living?
    • It does not have both RNA and DNA.
    • They are also without organelles or a nucleus. 
  3. What is a capsid?
    The protein coat of a virus that encapsulates the nucleic acid the virus holds.
  4. Where does a virus get its envelope from?
    Often stolen from host cell membrane
  5. How do animal viruses go about their business?
    They attach to membrane receptors and are then edocytosed. 
  6. Retroviruses
    • 1. Convert RNA to DNA using host cell machinery 
    • 2. Hold RNA code for reverse transcriptase and integrase in genome --- once these are transcribed, they help reverse transcribe the rest of their genome
  7. Lytic cycle
    • Immediate production of viral progeny. 
    • Latency period, the time between infection and cell bursting,  ends with cell death.
  8. Lysogenic cycle
    Viral nucleid acid is incorporated into host genome and remains dormant until stressed, at which point it enters the lytic cycle.
  9. Steps of viral infection.
    • 1. Attachment to host 
    • 2. Injection of material
    • 3. Endocytotically engulfed
    • 4. Use of host cell machinery & energy
    • 5. Assembly and release of viral progeny  
  10. Viral defense
    • 1. Antibodies 
    • 2. Vaccines (injection of antibodies or non-virulent strain)
  11. Fungi reproduction
    Alternation between haploid (faster) and diploid stages. 

    Hyphae lengthen through mitosis.

    • Asexual = good conditions
    • Sexual = bad conditions 

    Release spores in reproduction
  12. Yeast
    • 1. Unicellular fungi 
    • 2. reproduce via budding/cell fission
    • 3. Facultative anaerobes
  13. Properties of Fungi: 
    1. Organization of kingdom?
    2. Cellularity?
    3. Organelles?
    4. Membrane composition?
    5. Energy & Carbon source category?
    • 1. Divided into divisions (like plants) instead of phyla
    • 2. Multicellular except for yeast
    • 3. Have no centrioles 
    • (BUT HAVE MITOCHONDRIA) 
    • 4. Have cells walls made of chitin
    • 5. Saprophytes (dead material) ; heterotrops ; eukaryotes ; absorb, rather than ingest food
  14. Energy source classification
    • 1. Phototrophs - use light as energy source 
    • 2. Chemotrophs - oxidize matter for energy, N2 fixation
  15. Carbon source classification
    • 1. Autotrophs - CO2 fixing, self-nourishing
    • 2. Heterotrophs - use preformed organic molecules to obtain C
  16. Similarities between prokaryotes and eukaryotes:
    1. Nucleic acid
    2. Organelles
    3. Plasma membranes
    4. Cell walls
    5. Flagella
    • 1. both have RNA and DNA
    • 2. Both have ribosomes, but prokaryotes organelles are not membrane-bound or complex
    • 3. Both have plasma membranes but prokaryotes don't have cholesterol
    • 4. Cells walls of chitin & cellulose vs. peptidoglycan
    • 5. Eflagella made of MTs ; Pflagella powered by ATP via pump
  17. Eukaryotes cellularity & complexity
    Can be both unicellular and multicellular & possess nuclei and membrane-bound organelles.
  18. Phyla of Prokaryotes
    1. Archaea - similar to eukaryotes, reside in extreme conditions, do not possess peptidoglycan cell wall 

    2. Bacteria
  19. Gram-positive bacteria
    • 1. Stain purple 
    • 2. Thick peptidoglycan cell wall
    • Endospore formation (environmentally and temperature resistant)
  20. Gram-negative bacteria
    • 1. Stain pink 
    • 2. Thin peptidoglycan cell wall + LPS
    • 3. LPS plasma membrane acts as a protective barrier to antibodies and antibiotics
  21. Prokaryote qualities: 
    1. Complexity
    2. Genetic material
    1. Contain no complex, membrane-bound organelles OR nucleus 

    2. Possess small, double-stranged DNA and perhaps also plasmid
  22. Plasmids 
    May be foreign and can replicate independently from the nuclear genome

    Can be passed between bacterium to confer resistance 
  23. Bacterial growth: 
    • Bacterial growth is much more rapid than eukaryotic growth.
    • Growth slows when nutrients become scare and with crowding
  24. Bacterial reproduction
    Binary fission = aseual reproduction 

    • 1. No spindle fibers to allow for full separation
    • 2. Parent divided into 2 identical daughter cells
  25. Bacterial genetic recombination
    Not considered a real form of reproduction. 

    1. Conjugation: tranfer of genetic material via sex pilus, genomic DNA may also be transferred because plasmids can integrate into the genome (F & R)

    2. Transformation: Incorporation of foreign DNA from environment into genome

    3. Transduction: Injection of DNA via viral transduction
  26. Phylogeny
  27. Do fungi undergo mitosis?
    Yep. but no sexual reproduction

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