viruses, bacteria and archaea

• viruses are the smallest organisms in the world (15-300nm)
• all viruses are pathogens
• can be found anywhere in the world, some are responsible for the pandemic
• viruses are discovered by Dmitry Ivanovsky
• unicellular prokaryotic organisms, microscopic (1-10 mikrometers)
• founders of bacteria : Louis Pasteur, Robert Koch
• structure of bacteria: capsule(+slime), cell wall, plasma membrane, cytoplasm with ribosomes, nucleoid, flagella, sex pilus, plasmids, bacteriochlorophyll
• autotrophic: source of carbon CO2
• autotrophic: A)phototrophic, B)chemotrophic
• heterotrophic: source of carbon organic compounds
• heterotrophic: a)saprophytic, b)parasitic, c)symbiotic
• relation to oxygen: aerobic -oxygen dependent, anaerobic -dont need oxygen, facultative -can use oxygen or not
• All viruses are pathogens and can be found anywhere in the world
• Viruses consist of genetic information (DNA or RNA but never both), a capsid (protein coat encasing the genetic information), and a lipid envelope protecting the capsid
• Classification based on capsid shape includes helical, icosahedral, and complex (typical for bacteriophages with a head and tail)
• Viruses need host cells to reproduce and are intracellular parasites
• Viruses are divided into DNA viruses (contain one or two strands of DNA) and RNA viruses (contain one or two strands of RNA); retroviruses (e.g., HIV) change RNA into DNA after cell infection
• Examples of RNA viruses: common cold virus, influenza virus, HIV
• Host range can be restricted (virus is host-specific, e.g., HIV infects only humans) or wide (virus may infect more than one organisms)
• Host types include plant viruses (mostly RNA), animal viruses (includes human viruses, either DNA or RNA), fungal viruses (mostly RNA), and bacterial viruses (mostly DNA, infect bacteria and archaea)
• Oncogenic viruses can trigger cancer by causing mutations in cell DNA and uncontrollable division, e.g., hepatitis C virus, HPV virus, Epstein-Barr virus
• General mechanism of viral infection: Attachment, Entry, Genome replication and gene expression, Assembly, Release
• Bacteriophages must infect a host cell to reproduce; infection process stages are collectively called the lifecycle of the phage
• Lytic cycle: Phage hijacks host cell, makes new phages, causes cell lysis and death
• Stages of lytic cycle: Attachment, Entry, DNA copying and protein synthesis, Assembly of new phage, Lysis
• Lysogenic cycle allows phage to reproduce without killing host; phage DNA integrates into bacterial chromosome as a prophage
• Integrated phage DNA (prophage) is not active but can become active under certain conditions, triggering the remaining steps of the lytic cycle
• Bacteria are unicellular prokaryotic organisms, microscopic in size (1-10 μm)
• Bacteria have basic shapes: coccus (spherical), bacillus (rod-shaped), spirillum (spiral), spirochaete (cork-screw shaped), vibrio (curved-rod shape)
• Photosynthetic bacteria use bacteriochlorophyll for anoxygenic photosynthesis (no O2 produced)
• Types of bacteria:

  • Autotrophic: source of carbon is CO2
  • Phototrophic
  • Chemotrophic
  • Heterotrophic: source of carbon is organic compounds (OC)
  • Saprophytic: OC from dead, decaying organic matter
  • Parasitic: OC from the host (harmful), pathogenic
  • Symbiotic: OC from the host (cooperation), e.g., E.coli in the intestines
• Types of bacteria:

  • Phototrophic: source of energy is light
  • Chemotrophic: source of energy from chemical bonds gained in the process of oxidation or fermentation
  • Examples: nitrifying, iron-oxidising, sulphur-oxidising bacteria
• Reproduction:

  • Asexual (nepohlavné)
  • Binary fission (amitosis): don‘t undergo mitosis or meiosis, but replication of DNA occurs before division
  • Reproduce by budding (pučanie) - yeast
  • Reproduce by fragmentation (fragmentácia) - fibrous species
  • Endospores (spóry)
• Reproduction:

  • Sexual (pohlavné)
  • Conjugation: F (fertility) plasmid = sex pili
• Ecology and usage:

  • Decomposers of organic matter (clean up of oil spills, biological wastewater treatment plants)
  • Mineralisation of soil (enrich it and make it more fertile)
  • Bacterial insecticides
  • Biometallurgy (use of bacterial metabolism to produce metals)
  • Insulin production by inserting the insulin gene into a bacterial plasmid
  • Lactic acid fermentation and alcoholic fermentation
• Ecology and usage:

  • Some bacteria are pathogens responsible for various diseases
  • Antibiotics used for treatment of bacterial diseases, overuse can cause antibiotic resistance
• archaea Characteristics:

  • Unicellular prokaryotic organism
  • Domain of prokaryotic microorganism
  • Similar to bacteria in size, shape, motion, binary fission
  • Differences: cell wall contains pseudopeptidoglycan, different metabolism of NA, lipids, enzymes
  • Life‘s extremists, do not cause human diseases
• History:

  • First prokaryotes assigned to domain Archaea live in extreme environments
  • Extremophiles: lovers of extreme conditions, include extreme halophiles and extreme thermophiles
• Division according to the environment:

  • Methanogens (metanoarcheóny): produce methane gas as an energy metabolism waste product, anaerobic, found in soil, sewage water, digestive tract of ruminates
  • Ecologically used for wastewater treatment
  • Examples: Methanobacterium, Methanococcus, Methanosarcina
• Division according to the environment:

  • Halophiles (haloarcheóny): live in salty environments, usually extremely salty
  • Aerobic or anaerobic
  • Found in Great Salt Lake, the Dead Sea
  • Examples: Halobacterium, Halococcus