bio module 2

• water potential


  measure of tendency of water molecules to diffuse from one region to another (kilopascals)
• osmosis

  • 0 kpa- pure h20- 100% water
  • -200 kpa- dilute solution- some solute present
  • -500 kpa- concentrated solution- lots of solute/low water concentration
• isotonic

  • no net movement
  • solution where water p is equal to that inside the cell
• hypotonic

  • solution with higher water p than inside the cell
• hypertonic

  • solution with a lower p than inside the cell
• lytolysis


  animal cells in hypotonic solutions (burst)
• plasmolysis


  animal cells shrivel up in hypertonic solutions
• non polar: diffuses

  polar: has to use something else to get through
• facilitated diffusion


  diffusion of polar molecules across the membrane through carrier and channel proteins
• small non polar


  diffuse freely
• large non polar


  lipid soluble
• water(polar)


  in high concentrations, diffuses despite being polar
• small polar


  insoluble in lipids, rely on channel proteins
• large polar

  insoluble-use carrier proteins
• capsule


  protective waxy capsule-protects cell from phagocytosis and allows it to adhere to surfaces
• pili


  small, hair-like to attach to host cells (allow plasmid transmission)
• flagella


  projections to help them move
• nucleoid


  region of cytoplasm where prokaryotic dna located
• plasmid


  small loops of dna with extra genetic info
• cell wall


  made of petidoglycan
• staining theory

  • biological substances: colourless and transparent
  • stains- coloured chemicals bind to molecules in or on specimen
• methylene blue

  • all purpose stain
  • non-specific- binds to a variety of structures including nucleus
  • DNA/RNA, bacterial cells
• channel proteins


  have pores which allow ions in solution to pass through
• carrier proteins


  change their shape to carry specific molecules across membrane
• glycolipid


  carbohydrate chains attached to lipid molecules
• glycoprotein


  carbohydrate chains attached to protein molecules
• glycocalyx


  hydrophobic layer of carbohydrate molecules
• cholesterol

  • provides mechanical stability
  • regulates fluidity
  • reduces membrane permeability
• phospholipid

  • heads cover exterior of membrane
  • tails are in the centre of the membrane pointing towards one another
• peripheral proteins

  • enzymes to catalyse chemical reactions
  • antigens for immune system
  • receptor sites for signalling molecules
• latent heat of evaporation

  • water needs to be at high temps to turn into gas
  • sweat doesn't evaporate immediately
  • absorbs heat energy from body before evaporating
• density of pure water

  1.0g/cm3 - having density close to water makes it easier to swim or float
• • oxygen pulls electrons towards it making it slightly negative-makes hydrogen atoms slightly positive
  • water molecules are attracted to eachother
  • hydrogen bonds formed between surrounding water molecules
• hydrolysis

  • water splitting
  • molecules split apart with addition of water
• condensation

  • water formation
  • molecules joined together
• cohesion


  water molecules attracted to other water molecules - produces surface tension
• surface tension


  water moves towards water instead of air and makes solid-like surface
• water is a metabolite and cells metabolic reactions occur in aqueous solutions
• density and viscosity

  • water expands when frozen -lower density and floats(ice)
  • water is viscous - water molecules attracted to eachother
• solvent properties

  • water is a good solvent
  • has positive and negative charges
  • charges attract charges on other molecules and ions
  • allows substances to dissolve and be transported to different parts of an organism