Viruses and bacteria

• Viruses:

  • Biological significance: infect cells and cause diseases, need a host cell to replicate, can infect all types of organisms including humans, animals, and plants
• • Viruses are non-living structures that do not have cells, metabolism, or the ability to grow and reproduce without a host
• Prions:

  • Characteristics: consist of misfolded proteins
  • Structure: prion diseases like mad cow disease in animals, convert normal proteins into misfolded form leading to accumulation of abnormal proteins in the brain
• Bacteria:

  • Characteristics: first living things on earth, unicellular prokaryotes without a nucleus or other membrane-bound cell organelles
  • Significance: crucial roles in ecosystems like decomposition, practical applications in medicine, and helping immune function in humans
• Metabolism:

  • Autotroph: self-feeder, producing own food by sunlight or inorganic compounds
  • Chemotroph: break down organic molecules through chemical reactions
  • Chemoautotroph: produce food using inorganic compounds as a source of energy
  • Photoautotroph: produce their own food using sunlight as a source of energy
• Endosymbiosis theory:

  • Proposes certain organelles were once free-living bacteria engulfed by ancestral cells
• Lifestyle and reproduction of bacteria:

  • Lifestyle: free-living in soil, body, water, form symbiotic relationships with plants or animals, some are pathogenic causing diseases, others play roles in nutrient cycling
  • Reproduction: reproduce by binary fission, asexual, a single bacterium divides into 2 daughter cells
• Recombinant bacteria:

  • Genetically modified to contain DNA from another organism
• • General characteristics: unicellular, eukaryotic, tiny particles with genetic material surrounded by a protein coat (capsid)
• • Examples of viral diseases: COVID-19, common cold, hepatitis B, cold sores, AIDS, measles, herpes, Ebola
• • Treatment for viral diseases: lots of fluid intake, rest, over-the-counter medication, vaccines