health/disease

• health: a state of physical, emotional and mental wellbeing
• disease: an illness/sickness defined by a set of signs and symptoms
• signs and symptoms mark the beginning of a disease
• pathogen: any organism that causes disease
• parasitic: causes harm to host organism, living in/on host
• once pathogens enter our body, our immune cells detect them
• white blood cells: WBCs
• white blood cells (WBCs) are the main detectors of pathogens
• white blood cells are the main cells to destroy pathogens
• pathogens aim to multiply and survive in the body
• pathogens release toxins in the body, damaging cells, causing the body's biological processes to malfunction
• pathogens trigger an immune response, which can include inflammation (how the body tries to get rid of infection)
• types of pathogens include: bacteria, viruses, fungi, worms, prions
• a virus is an infectious microscopic pathogen that infects and causes harm to its host. can only survive within host
• viruses are smaller than bacteria
• viruses have a protective protein shell called a capsid which has DNA or RNA within. some viruses have an outer membrane (envelope)

  
• there are 5 steps to the virus lifecycle

  
• steps of virus lifecycle:

  1. attachment: virus binds to host cell via receptor
  2. entry: virus enters cell
  3. genome replication: virus's genes (DNA and RNA) are copied and expressed to make viral proteins.
  4. assembly: newly formed capsid proteins come together to form new full capsids around viral DNA
  5. release: new virus particles exit cell and go off to infect others. release can also kill host organism
• viruses are parasitic
• limiting contact between an infected person and others is the simplest way to control viral spread
• antibiotics have no effect on viruses. they only work on bacteria
• bacteria are unicellular microorganisms, they do not possess a nucleus or membrane bound organelles.
• some bacteria are pathogenic (bad) whereas some are symbiotic (good)
• bacteria can be found everywhere: e.g. water, soil, plants, earth's crust, hot springs, glaciers, humans etc.
• examples of pathogenic bacteria: salmonella, E.coli, diplococcus
• good bacteria are often found in guts and manage bad bacteria
• probiotics are the good bacteria.

  prebiotics are the food for the good bacteria.
• bacteria come in different shapes and are around 1-2nm in size

  
• structure of bacteria

  
• flagellum is for the movement of the cell
• ribosomes are used for protein synthesis
• pilus are for cell to cell interactions
• the capsule is for protection and adhesion.
• the cell wall is for the cell's structure
• the plasma membrane is for protection
• if all specific requirements are present, bacteria can multiply through binary fission
• the specific requirements bacteria need to multiply are:

  • nutrients (amino acids/carbs)
  • oxygen
  • temperature
  • water
  • pH
• the bacterial growth curve

  
• bacterial growth curve:

  • lag phase: population remains constant
  • exponential phase: bacteria multiplies through binary fission quickly
  • stationary phase: population remains constant as amount of bacteria dying equates to amount of bacteria multiplying
  • death phase: bacteria stop multiplying and begin to die
• a fungus/fungi is a eukaryotic organism that primarily produces spores. e.g. yeasts, moulds, mushrooms