classification, viruses, bacteria

• Species are a group of organisms that can interbreed in nature and produce fertile offspring
• Identification of species can be done through:

  • Morphology: body shape, size, and other structural features
  • Advantage: simple, usually used for plant identification
  • Disadvantage: deciding differences (what is considered big, small, etc)
  • Biological: if species can mate and produce offspring
  • Advantage: widely used by scientists
  • Disadvantage: cannot be applied in all cases
  • Phylogeny: comparing evolutionary history
  • Advantage: can be applied to extinct species, considers information from DNA analysis
  • Disadvantage: evolutionary history is not known for all species
• Taxonomy is the branch of biology that identifies, names, and classifies species based on natural features
• Classification involves arranging species in categories from most general to most specific, according to structural, biomedical, and evolutionary similarities
• Binomial Nomenclature:

  • Most of the time, only the last two taxa, genus, and species are used
  • Example: Humans = Homo sapiens
  • Underlined if written, italics if computerized
  • First word capitalized, second lowercase
• Ways to determine how species are related:

  1. Sharing a common ancestor

  2. Anatomical evidence: structure and form of an organism

  3. Physiological evidence: studying physical/chemical functioning of the organism, involving proteins with genetic information

  4. DNA evidence: studying specific sequences of nucleotides that make up genes
• Classifying types of biodiversity:

  • Species diversity: variety and abundance of species in a given area
  • Genetic diversity: variety of heritable characteristics in a population
  • Ecosystem diversity: variety of ecosystems in the biosphere
  • Biotic factors: interacting populations of species
  • Abiotic factors: altitude, latitude, geology, soil nutrients, climate, and light levels
• Ecosystem services are benefits provided by sustainable ecosystems, such as wetlands storing water, filtering water, and providing habitats for commercial species
• Resilience is the ability of an ecosystem to remain functional and stable in the presence of disturbances, with ecosystems having greater species diversity showing higher resilience
• Prokaryotes are represented by two domains: Bacteria and Archaea
• Archaea and Bacteria share characteristics such as:

  • No membrane-bound nucleus and organelles
  • Single circular chromosome
  • Small pieces of genetic information
  • Small, single-celled organisms
• Comparing Respiration:Both bacteria and archaea can grow under aerobic or anaerobic conditions
• 
  

  • Archaea thrive in harsh conditions resembling those when life first developed on Earth
• Endosymbiosis:

  • Larger cell engulfs a smaller cell with a specialized function
  • The engulfed cell survives and becomes part of the larger cell
  • Probable origin of mitochondria and chloroplasts
• Comparing Nutrition:

  • Archaea and Bacteria obtain energy in various ways:
  • Bacteria may consume other organisms
  • Archaea can produce energy through photosynthesis, methanogenesis, or chemosynthesis
• Comparing Reproduction:

  • Bacteria and Archaea reproduce through binary fission or conjugation
  • Binary Fission occurs when prokaryotes find themselves in favorable conditions
  • Conjugation allows exchange of small pieces of circular DNA
• Antibiotics and Antibiotic Resistance:

  • Antibiotics are chemicals that inhibit the growth of microorganisms
  • Antibiotic resistance arises from natural variation within bacterial populations
  • Endospores are thick-walled structures formed by some bacteria under unfavorable conditions
• name the parts of the bacteria (typical structure):

  A) single circular chromosome

  B) DNA plasmid

  C) Flagellum

  D) Pilli

  E) cell membrane

  F) cell wall

  G) capsule

  
• 8 levels/taxa

  domain, kingdom, phylum, class, order, family, genus, species
• Viruses are very tiny infectious agents that cause disease in plants and animals
• Viruses are hundreds of times smaller than most cells
• Viruses are not considered truly alive as they cannot exist independently without a host
• Viruses replicate, not reproduce, and contain genetic material such as RNA or DNA
• Some viruses can expand their host range through mutations and jump to other species, a process known as zoonotic disease when it goes from animals to humans
• Viruses have no organelles and a simple structure, classified based on protein capsid and genetic material
• Viruses were previously named based on the disease they cause, folklore, and the tissues they infect
• Viruses consist of a protein coat called a capsid surrounding their genetic material (DNA/RNA)
• Quick replication in the lytic cycle leads to immediate symptoms
• Provirus remains dormant until triggered
• Retroviruses undergo an additional step called integration or provirus formation
• DNA viruses have stable genes, and the same vaccine can be used against them year after year, requiring vaccination only 1-2 times in a lifetime
• RNA viruses have genes that mutate quickly, making it difficult to create vaccines against them. Vaccination is needed yearly as antibodies must change to identify mutated forms of RNA viruses
• Vaccination involves solutions prepared from viral components or inactivated viruses to trigger the body's immune system, effectively reducing disease
• Gene therapy is sometimes used for genetic complications or when individuals do not want to pass on certain genes to offspring
• In gene therapy, cells are removed from the patient, altered viruses with inserted genes are mixed with the patient's cells, and the genetically altered cells are injected back into the patient
• Lyctic cycle labelling:

  A) attachment

  B) Injection

  C) Replication

  D) Assembly

  E) Lysis

  
• Lysogenic cycle labelling:

  A) Incorporation

  B) Provirus

  C) Provirus

  
• endosymbiosis is when a large cell engulfs a smaller cell and the engulfed cell survives, becoming part of the larger cell
• microbiologists must stain bacteria to react with protein, so they can easily view bacteria. What is this process called?

  gram stain
• gram positive bacteria: have a thick protein layer on their cell wall and stain purple

  gram negative bacteria: have a thin protein layer on their cell wall and stain pink