M4 Acellular and Prokaryotic Microbes

• Virions

  Complete virus particles are called?
• Oncogenic viruses or oncoviruses

  Cause specific types of cancer
• Capsomeres

  Protein units
• Capsid

  Protein coat
• Enveloped viruses

  Have an outer envelope composed of lipids and polysaccharides
• Double-stranded DNA viruses and Single-stranded RNA viruses

  Most viral genomes
• Four categories of viruses

  Double-stranded DNA viruses

  Single-stranded RNA viruses

  Single-stranded DNA viruses

  Double-stranded RNA viruses
• Animal viruses

  Escape from their host cells either by lysis of the cell or by budding
• Steps in the multiplication of animal viruses are:

  • Attachment

  • Penetration

  • Uncoating

  • Biosynthesis

  • Assembly
• Latent Virus Infections

  Viral infections in which the virus is able to hide from a host’s immune system by entering cells and remaining dormant
• Oncogenic viruses or oncoviruses

  These viruses cause cancer
• Human immunodeficiency virus (HIV)

  This virus causes acquired immunodeficiency syndrome (AIDS)
• HIV

  It is an enveloped, single-stranded RNA virus
• CD4+ cells

  The primary targets for HIV
• Antiviral agents

  Are drugs that are used to treat viral infections
• True

  Antibiotics are not effective against viral infections
• Bacteriophages

  Viruses that infect bacteria are known as?
• Virulent bacteriophages and Temperate bacteriophages

  Two categories of bacteriophages
• Lytic cycle

  Ends with the destruction of the bacterial cell
• Five steps in the lytic cycle

  • Attachment

  • Penetration

  • Biosynthesis

  • Assembly

  • Release
• Viroids

  Are short, naked fragments of single-stranded RNA, which can interfere with the metabolism of plant cells
• Viroids

  Are transmitted between plants in the same manner as viruses
• Prions

  Are small infectious proteins that cause fatal neurologic diseases in animals and humans
• Prions

  Are the most resistant disinfectant of all pathogens
• Three categories of bacteria based on shape:

  Cocci (round bacteria)

  Bacili (rod-shaped bacteria)

  Curved and spiral-shaped bacteria
• Cocci may be seen singly or in pairs (diplococci), chains (streptococci), clusters (staphylococci) packets of four (tetrads) or packets of eight (octads)
• Bacilli

  Referred to as rods; they may be short or long, thick or thin, and pointed or with curved or blunt ends
• Bacilli in pairs (diplobacilli), chains (streptobacilli), long filaments or branched
• Coccobacilli

  Extremely short bacilli
• Borrelia hermsii

  The cause of relapsing fever, in a stained blood smear
• Three major categories of Staining Procedure

  1. Simple staining procedure
  2. Structural staining procedures
  3. Differential staining procedures
• Three Structural Staining Procedures

  • Capsule staining

  • Spore staining

  • Flagella staining
• Fixation process

  Serves to kill organisms, preserve their morphology and anchor the smear to the slide
• Heat fixation

  Not a standardized technique; excess heat will distort bacterial morphology
• Methanol fixation

  A standardized technique; the preferred method
• Gram-positive

  Bacteria end up being blue to purple
• Gram-negative

  Bacteria end up being pink to red
• The cell walls of Gram-positive bacteria have a thick layer of peptidoglycan
• The cell walls of Gram-negative bacteria have a thin layer of peptidoglycan
• Heat

  It is used to soften the waxes in the cell wall