Midterms MICRO2

Cards (30)

  • Phototrophic
    Obtaining energy from sunlight to synthesize organic compounds for nutrition
  • Heterotrophic
    An organism that eats other plants or animals for energy and nutrients
  • Prokaryotic cells
    • Lack a nucleus and membrane-bound organelles
    • Bacteria and related microorganisms
  • Eukaryotic cells
    • Contain a nucleus and membrane-bound organelles
    • Animals, plants, fungi, and protists
  • Viruses
    • Microscopic particles that infect cells of other organisms
    • Carry conventional genetic material in the form of DNA or RNA but they cannot reproduce on their own
  • Virus Classification Hierarchy
    • Realm
    • Kingdom
    • Phylum
    • Class
    • Order
    • Family
    • Genus
    • Species
  • Morphological Types of Viruses
    • Helical Viruses
    • Icosahedral Viruses
    • Enveloped Viruses
    • Complex Viruses
  • Helical Viruses
    • The viral nucleic acid coils into a helical shape and the capsid proteins wind around the inside or outside of the nucleic acid, forming a long tube or rod-like structure
  • Icosahedral Viruses

    • The icosahedron is made up of equilateral triangles fused together in a spherical shape
    • The genetic material is fully enclosed inside of the capsid
    • Viruses with icosahedral structures are released into the environment when the cell dies, breaks down and lyses, thus releasing the virions
  • Enveloped Viruses
    • Has an outer wrapping or envelope
    • The envelope comes from the infected cell or host in a process called "budding off"
  • Complex Viruses
    • Structurally complex viruses incorporate a larger variety of components into their capsids than simple viruses
    • They may contain accessory proteins with specific architectural or functional roles or incorporate non-proteic elements such as lipids
  • Genome Types
    • DNA Viruses
    • RNA Viruses
    • Reverse-Transcribing Viruses
  • DNA Viruses
    • Made of deoxyribonucleic acid
    • Present everywhere, especially in the marine ecosystem
    • Divided into three major categories: double-stranded (ds) DNA viruses, single-stranded (ss) DNA viruses, and pararetroviruses
  • RNA Viruses
    • Made of ribonucleic acid
    • dsRNA has many hosts, such as bacteria, animals, fungi and humans
    • Have a higher mutation rate when compared to DNA viruses
    • Their genetic diversity makes it difficult to produce effective vaccines against them
  • Reverse-Transcribing Viruses

    A process by which viruses generate complementary DNA (cDNA) from an RNA template, using enzymes called reverse transcriptases
  • Baltimore Classification Groups
    • Group I - dsDNA viruses
    • Group II - ssDNA viruses
    • Group III - dsRNA viruses
    • Group IV - positive-sense ssRNA viruses
    • Group V - negative-sense ssRNA viruses
    • Group VI - ssRNA viruses with a life cycle intermediated with DNA
    • Group VII - dsDNA viruses with a life cycle intermediated with an RNA
  • Bacteriophages
    Viruses that infect bacteria
  • Viral Multiplication in Bacteriophages

    1. Adsorption
    2. Penetration
    3. Assembly
  • Uses of Bacteriophages
    • Destroy bacterial pathogens
    • Treat bacterial infection
    • Prevent food contamination
  • Steps in Animal Virus Multiplication
    1. Adsorption
    2. Penetration
    3. Uncoating
    4. Replication
    5. Assembly
    6. Release
  • Viral Infections
    • Abortive Infections
    • Cytocidal Infection
    • Persistent Infection
  • Abortive Infections

    Infections of nonpermissive cells where no viral production occurs
  • Cytocidal Infection
    An infection that results in cell death either from cell lysis, apoptosis, or the accumulation of cytopathic effects
  • Persistent Infection
    • Characterized as those in which the virus is not cleared but remains in specific cells of infected individuals
    • Do not cause cell death
  • Types of Persistent Infections
    • Chronic infections that are not lytic but productive
    • Latent infections with limited macromolecular synthesis but no virus synthesis
    • Slow infections, characterized by a prolonged incubation period without prominent morphological and physiological changes to the host cell
    • Transforming infections, in which the viral nucleic acid may remain in specific eukaryotic host cells indefinitely, and a virus may or may not be produced
  • Viroids
    • Short, naked fragments of single-stranded RNA, which can interfere with the metabolism of plant cells
    • Transmitted between plants in the same manner as viruses
    • Examples of plant diseases caused by viroids are potato spindle tuber and citrus exocortis
    • Do not cause animal disease
  • Virusoids
    • Essentially viroids that have been encapsulated by a helper virus coat protein
    • RNAs, have genomes from 220 to 338 nucleotides long, their genomes are circular and single-stranded, and they have ribosome activity
    • Replicate in the cytoplasm of their host, using an RNA-dependent RNA polymerase
    • Require that the host cell be infected with a specific helper virus
    • Associated with plant infections
  • Prions
    • Infectious agents that do not have a nucleic acid genome
    • A normal protein in animal tissue, but when these particles become abnormally folded and shaped they become proteinaceous infectious particles that are not cellular organisms or viral particles
    • Prion diseases are transmissible from host to host of a single species
  • Size of viruses varies from very small, from 20nm to 450nm.
  • Capsid
    Viral Coat; Genetic material carried in a "shell"