résumé microbiologie

• Phylogenetic tree titled "Tree of Life":

  • Shows evolutionary relationships between different groups of organisms
  • Based on the idea that all organisms are descended from a common ancestor
  • Organisms divided into 3 domains: Bacteria, Archaea, and Eukarya
  • Bacteria domain includes prokaryotes, Archaea domain includes archaea, and Eukarya domain includes eukaryotes

  
• Differences between prokaryotic and eukaryotic cells:

  • Prokaryotic cells are smaller and simpler, lack a nucleus or other membrane-bound organelles
  • Eukaryotic cells are larger, more complex, have a nucleus and other membrane-bound organelles

  
• Structure of a virus:

  • Components: genetic material (RNA or DNA), capsid (protein coat), envelope (lipid bilayer)
  • Capsid protects genetic material, made of capsomers
  • Envelope surrounds capsid, helps virus enter host cells

  
• Bacteriophage T4: virus that infects bacteria

  
• Assembly of a bacteriophage:

  • Consists of a head (contains DNA) and a tail (used to attach to bacterium and inject DNA)
  • Phage's DNA transcribed and translated by bacterium, proteins assembled into new phage particles

  
• Lytic cycle and lysogenic cycle of a virus

  
• Cartoon showing lysogenic conversion:

  • Bacteriophage infects bacterium, integrates DNA into bacterium's genome
  • Gives bacterium new properties, such as toxin production

  
• Steps of viral replication

  
• Steps of retrovirus replication

  
• Diagram showing metabolic activity of a cell depends on surface area to volume ratio:

  • E. coli bacterium has higher metabolic activity due to large surface area compared to a cow

  
• Types of bacteria

  
• General microbiology:

  • Microbial world's uniqueness: ancient origin, diversity, adaptability
  • Classification of microorganisms: viruses, discovery, structure, classification, biological cycle

  
• Phylogenetic tree titled "Tree of Life":

  • Shows evolutionary relationships between different groups of organisms
  • Based on the idea that all organisms are descended from a common ancestor
  • Divided into three domains: Bacteria, Archaea, and Eukarya
  • Bacteria domain includes prokaryotes, Archaea domain includes archaea, and Eukarya domain includes eukaryotes

  
• Assembly of a bacteriophage:

  • Consists of a head (contains DNA) and a tail used to attach to and inject DNA into bacterium
  • Phage's DNA is transcribed and translated by the bacterium
  • Phage's proteins are assembled into new phage particles
  • New phage particles are released from the bacterium to infect new bacteria

  
• Lysogenic conversion:

  • Bacteriophage infects bacterium and integrates its DNA into the bacterium's genome
  • Gives the bacterium new properties, such as toxin production

  
• Types of bacteria:

  • Parasites incapable of multiplying without a host
  • Specificity varies, determined by surface proteins of viruses and host cell receptors
  • Examples of generalists: Avian flu, Rabies
  • Examples of specialists: Measles (human)
  • Often specific to tissues or even cells
• Bacteriophages:

  • Among the first viral genes transcribed: A Dnase destroys the genome in the host cell, while the viral DNA is protected
• Quantification of viruses:

  • Indirect quantification method involving agar layers and phage suspension
  • Each virus forms a lysis plaque after incubation
• Defense mechanisms of bacteria:

  • Crisper Cas for immunity, gene exchange through conjugation, genomic mutation, capsule or receptor changes to prevent infection
• Lytic and lysogenic cycles of bacteriophages:

  • Some temperate phages can integrate into the host genome (prophage) and replicate without lysing the cell
• Influence of prophage on the bacterial host cell:

  • During the lysogenic phase, the prophage genome is transcribed with the host's, providing ecological advantages or changing the host's lifestyle
• Study of phages:

  • Contributions to genetic discoveries, sequencing methods, restriction enzymes, cloning vectors
• Phages and society:

  • Potential therapeutic applications
• Assembly of a bacteriophage:

  • Consists of a head with DNA and a tail used to attach to a bacterium and inject DNA
  • Phage's DNA is transcribed and translated by the bacterium
  • Phage's proteins are assembled into new phage particles
  • New phage particles are released from the bacterium to infect new bacteria

  
• Lysogenic conversion process:

  • Bacteriophage infects a bacterium and integrates its DNA into the bacterium's genome
  • Gives the bacterium new properties, such as toxin production

  
• Metabolic activity of a cell depends on the ratio of its surface area to its volume:

  • E. coli bacterium has a higher metabolic activity than a cow due to its larger surface area relative to volume

  
• Types of bacteria:

  • Unicellular organisms without a nucleus
  • Small size, high metabolic activity, metabolic versatility, adaptability

  
• Les phages et la société:

  • Les phages ont un potentiel curatif contre les infections bactériennes et sont utilisés dans la conservation alimentaire et pour réduire les antibiotiques dans les élevages
• Les virus des animaux:

  • La plupart des virus d'animaux ont une enveloppe membranaire qui permet l'endo- et l'exocytose
  • Cycle de réplication d'un virus à ARN enveloppé
• Les virus des plantes:

  • Plus de 2000 virus de plantes connus, transmission horizontale, lutte par prévention, détection précoce et élimination des plantes contaminées
• Les viroïdes:

  • Petites molécules d'ARN circulaire, spécifiques aux plantes, capables de se multiplier et d'interférer avec la croissance végétale
• Structure of a virus:

  • Components: genetic material (RNA or DNA), capsid (protein coat), envelope (lipid bilayer)
  • Capsid protects genetic material, made of capsomers
  • Envelope surrounds capsid, helps virus enter host cells, some have a glycoprotein coat

  
• Assembly of a bacteriophage:

  • Consists of a head (contains DNA) and a tail used to attach to bacterium and inject DNA
  • Phage's DNA transcribed and translated by bacterium, proteins assembled into new phage particles
  • New phage particles released from bacterium to infect new bacteria

  
• Lysogenic conversion process:

  • Bacteriophage infects bacterium, integrates its DNA into bacterium's genome
  • Gives bacterium new properties, such as the ability to produce toxins

  
• Diagram showing metabolic activity of a cell depends on its surface area to volume ratio:

  • Illustrates with a cow (large volume, small surface area) and E. coli bacterium (small volume, large surface area)
  • E. coli bacterium has higher metabolic activity due to its ratio

  
• Types of bacteria:

  • Very diverse, base of mitochondria and chloroplasts
  • >5000 described species, but only 1-5% cultured (estimated diversity of 1 billion species)

  
• Characteristics of bacteria:

  • Small size, advantages include ease of absorption/excretion, surface area to volume ratio affecting absorption ease
  • Growth potential, limitations include food availability, environmental conditions, competition between bacteria