microbiology

• Bacteria with thicker walls are more resistant to antibiotics that target the cell wall.
• Peptidoglycan consists of alternating sugars (N-acetylglucosamine and N-acetylluramic acid) crosslinked by short polypeptide chains.
• The cell wall is composed of peptidoglycan, which provides strength to the bacterial cell.
• Microorganisms can reproduce through various methods, including binary fission, budding, and spore formation.
• Bacterial conjugation allows for horizontal transfer of genetic material between bacteria.
• Microbial growth refers to the increase in the number of microorganisms in a population.
• The outer membrane is composed of lipopolysaccharides (LPS) and phospholipids, which form a bilayer structure similar to eukaryotic cells.
• The peptidoglycan layer is responsible for maintaining bacterial shape, providing structural support, and protecting against osmotic lysis.
• Penicillin inhibits the synthesis of peptidoglycan by binding to penicillin-binding proteins (PBPs), which prevents transpeptidation reactions from occurring.
• Penicillin inhibits the synthesis of peptidoglycan, leading to lysis of the cell wall and death of bacteria.
• Gram staining distinguishes between gram-negative and gram-positive bacteria based on their ability to retain crystal violet dye.
• Binary Fission - Asexual reproduction where one parent cell divides into two daughter cells
• Budding - A form of asexual reproduction where a new organism grows out from an existing organism as a small projection called a bud
• Spore Formation - A type of asexual reproduction where some bacteria produce hardy structures called endospores that allow them to survive harsh conditions like extreme temperatures or lack of nutrients
• Viruses have a nucleic acid core surrounded by a protein coat called a capsid.
• Binary fission is a type of cell division where one parent cell splits into two identical daughter cells.
• Lipopolysaccharides: contains lipid and carbohydrate  
• Porins: span outer membrane – allow passage for food and hydrophilic molecules
• Porins: span outer membrane – allow passage for food and hydrophilic molecules 

  Stabilizes outer membrane structure – stops antibiotics from entering – protects pathogenic bacteria from hosts defenses  
• Lipid a portion – endotoxin – cytokine release -> septic shock  
• plasmids: 

  Thousands isolated from strains of E. coli  

  Possible to make them in the lab – plasmid vectors for cloning 

  Spread naturally by conjugation – between a donor cell a recipient cell – sex pilus  

  Typically circular 
• DNA must integrate into chromosome to transform recipient cell = Transformants
• Transduction 

  Virus can make bactera sick – bacteriophages  
• transducting phage  

  • Not all bacteriophages can transduce and not all bacteria are transductible
• Conjuguation: 

  Cell- to –cell contact allowing transfer of DNA  

  Plasmids are self – transmissable by conjugulation  
• Water = 70 to 80% of wet weight  

  Proteins= around 55% of cell dry weight  
• Heterotrophic nutrition: saprophytes -  release enzymes that break down dead bodies of animals and plant remains
• Symbiotic: symbiotic relationship – both host and  pathogen benefit from interaction – assists plants in nitrogen fixation – biological nitrogen
• Carbon and energy are required for: cell structure – synthesis of enzymes – maintenance and repair – growth and multiplication – transport and motility  
• Oxidation = loss of electron 
• Reduction = gain of electron 
• Energy released from redox reaction – transfer to phosphate compounds in form of high energy phosphate bonds  
• bacterial growth curve - log phase - exponentially growth phase - stationary phase - death phase
• lag phase - time it takes for bacteria to grow - metabolic activity with no division
• log phase = rapid cell division
• stationary phase - nutrients depleted - growth slows - spores form
• Factors influencing each stage of bacterial growth: 

  • Ph  
  • Nutrition concentration  
  • Temp 
  • Gas conditions  
  • Water  
  • Osmotic pressure  
• Types of bacterial respiration: 

  Aerobic = uses oxygen (obligates aerobes) 

  Anerobic = no oxygen – uses fermentation (obligates anaerobes) 
• Facultative aerobes – respire aerobically will switch to anaerobically if oxygen is deficient  

  Facultative anaerobes – respire anaerobically will switch to aerobically if oxygen is available 
• Primary metabolic – directly involved in normal growth – something the organism produces naturally – enzymes – amino acid – vitamins – ethanol