BIO Exam 2

• A virus is:

  obligate, intracellular parasite that uses a host cell to copy themselves & make viral proteins
• Endemic:

  disease is always present (ex: STI)
• epidemic:

  disease that rapidly infects a large # of individuals over a widening area (ex: COVID-19 in Wuhan province when it was just starting
• Pandemic:

  a worldwide epidemic (ex: The Spanish flu 1918-1919)
• 1st phase of replicative growth of viruses:

  attachment to host cell & entry into the cytosol
• 2nd phase of replicative growth of viruses:

  viral genome transcription & viral protein production
• 3rd phase of replicative growth of viruses:

  viral genome replication
• 4th phase of replicative growth of viruses:

  assembly of a new generation of virions
• 5th phase of replicative growth of viruses:

  exit from the infected cell
• 6th & final phase of replicative growth of viruses:

  transmission to a new host
• Lytic cycle:

  replicative, tons of virions made, kills the host, 99% more common
• Lysogenic cycle:

  virus integrates into host DNA, no virions, switch to lytic
• Epidemic transforming into pandemic:

  COVID-19 pandemic originally began in the Wuhan province in China. Respiratory disease that had some people asymptomatic and spread worldwide.
• Lysogenic cycle:

  viral genome integrates into the host genome, every time the host replicates the viral genome is also replicated, no virions made
• Lateral gene transfer:

  introduces foreign genes into cellular genomes & shuttles genes from 1 organism to another. You can cross species to species, even different species.
• How does lateral gene transfer relate to viruses?

  Viruses can introduce foreign genes into a genome
• The escaped gene hypothesis:

  suggests that viruses descend from gene sets that physically escaped from bacterial & eukaryotic chromosomes
• Different ways that viruses copy their genetic material:

  • they depend on the host cell for nucleotide monomers
  • some viruses depend on the host cell DNA polymerase to replicate their genomes
  • RNA viruses supply their own enzyme to make copies of their genome
• HIV:

  reverse-transcribing virus
• Koch's postulates:

  • pathogen/microorganism must be in the infected and absent from healthy individuals
  • pathogen must be cultured from the diseased
  • the infected must recapitulate the disease
  • the microorganism must be matched to the original microorganism
• Bioremediation:

  use of living organisms, usually bacteria & archaea, to clean up sites polluted with organic solvents
• How are high-GV Gram positive organisms distinguished from low-GC Gram positive organisms?

  Ribosome analysis. Ribosomal RNA is easy to remove from the bacteria & we have a large library of rRNA, we compare them & count the differences to tell them apart.
• Which group of bacteria accounts for the majority of our antibiotics?

  Actinobacteria (more specifically Actinomycete - Streptomyces)
• How are dead zones formed?

  Too much ammonia in fertilizer, where it meets bacteria in soil, releasing nitrate/nitrite as waste, & nitrates cause pollution in aquatic ecosystems. This decreases the oxygen content & causes nothing to be able to live in these zones.
• Why are cyanobacteria important to life on this planet?

  Responsible for changing Earth's atmosphere to one with a high concentration of oxygen. They are also important in the nitrogen cycle & are a primary food source.
• Beneficial uses for bacteria:

  • bioremediation
  • antibiotics
  • food industry (ex: yogurt)
  • helpful in digestion and neutralizing toxins
• Understand what happens when Plasmodium is transferred from mosquitos to humans.

  Chronic infectious disease - malaria
• Process of malaria:

  infected female mosquito bites a person, injecting Plasmodium parasites into the bloodstream & travel to the liver. Once parasites are mature, they leave the liver & infect the red blood cells. Some parasites burst from red blood cells & turn into gametes, go into gut wall of mosquito, & fertilize. Then rupture the cell & migrate to the salivary glands. Reproduce by using blood meals, & identified using a blood test.
• Which evolutionary mechanism plays a role in mosquito resistance to pesticides?

  natural selection
• What are diatoms? Where are they found?

  type of plankton (photosynthetic protists) that are microscopic, unicellular organisms surrounded by glass-like cell wall of silicon dioxide found drifting in open oceans or lakes
• Endosymbiosis theory:

  theory that mitochondria & chloroplasts evolved from prokaryotes that were engulfed by host cells, & these host cells were often protists. Probably had a bacteria living inside of a protista & that's how we ended up with mitochondria & chloroplasts
• Secondary endosymbiosis:

  predatory cell engulfed a chloroplast-containing protist & retained its chloroplasts (4 organelles?)
• 1st step of Gram stain and what G+ & G- look like:

  • primary stain - crystal violet (dye)
  • G+ looks purple
  • G- looks purple
• 2nd step of Gram stain and what G+ & G- look like:

  • Mordant (chemical hardener) - Iodine
  • G+ looks purple
  • G- looks purple
• 3rd step of Gram stain and what G+ & G- look like:

  • Decolorizer - Alcohol/Acetone
  • G+ looks purple
  • G- has no color
• 4th step of Gram stain and what G+ & G- look like:

  • Counterstain - Safranin (dye)
  • G+ looks purple
  • G- looks pink
• 2 common bioremediation strategies:

  • Fertilizing contaminated sites to encourage growth of existing bacteria & archaea (adding nutrients to ocean? so b/a currently there increase in pop.)
  • Seeding (adding) specific species of bacteria & archaea not already present in contaminated sites (introduce new b/a not already present to polluted sites to help break down the pollutants)
• Which of the following parts in the human body cannot be infected by a virus?

  • skeletal muscle
  • brain
  • blood cells
  • none of the listed responses are correct
• Which of the following is found in the viral envelope?

  viral envelope proteins
• The lytic cycle is distinguished from lysogeny based upon which of the following?

  The lytic cycle kills the host, & lysogeny keeps the host alive.