key concepts

• what is a eukaryotic cell

  cell that contains a nucleus and membrane-bound organelles
• examples of eukaryotic cells

  animal cell

  plant cell
• what is a prokaryotic cell


  a cell containing no nucleus or memory-bound organelles

  single-celled organism
• example of prokaryotic cell

  bacteria cell
• what organelles do animal cells contain

  cytoplasm

  nucleus

  ribosomes

  mitochondria

  cell membrane
• what is a nucleus

  stores genetic material

  controls cell activities

  found in animal cell, plant cell
• what is cytoplasm

  jelly-like substance

  where chemical reactions take place

  contains dissolved nutrients

  found in animal cell, plant cell
• what is mitochondria

  where aerobic respiration takes place

  produces energy in form ATP

  found in animal cell, plant cell
• what are ribosomes

  needed for protein synthesis

  found in animal cell, plant cell
• what is the cell membrane

  controls movement of substances in/out of a cell

  found in animal cell, plant cell
• what organelles do plant cells contain

  cytoplasm

  nucleus

  ribosome

  mitochondria

  cell membrane

  cell wall

  chloroplasts

  permanent vacuole
• what are chloroplasts


  contains green chemical (chlorophyll) which absorbs light for photosynthesis

  found in plant cell
• what is the permanent vacuole

  filled with cell sap to keep cell swollen

  found in plant cell
• what is the cell wall

  needed for structure, support, protection

  contains cellulose (plant cell only)

  found in plant cell, bacteria cell
• what organelles do bacteria cells contain

  chromasomal dna

  plasmid dna

  flagellum

  cell wall
• what is chromasomal dna

  loose strand of dna (not in nucleus)

  controls cell activities

  found in bacteria cell
• what is plasmid dna


  small, closed circles of extra dna

  moves from bacterium to bacterium (passed along, varied)

  found in bacteria cell
• what are flagellum

  rotate/move in whip-like motion

  help move cell

  found in bacteria cell, sperm cell
• what is cell differentiation

  when an unspecialised cell turns into a cell with a specific function

  examples: red blood cell, skin cell, sperm cell (approx 200 in humans)
• how is a sperm cell specialised

  haploid nucleus

  acrosome contains enzymes to penetrate egg cell

  mitochondria provides energy to swim

  tail to swim
• how is an egg cell specialised

  halploid nuclus (contains 1/2 genetic material)

  cytoplasm contains nutrients for embryo

  forms cell membrane after fertilisation so no more sperm can enter
• how are ciliated epithelial cells specialised

  have cilia on surface which moves fluids/particles up the trachea
• magnification of a microscope

  = magnification of eyepiece x magnification of objective lens
• magnification of image

  = size of image / actual size

  I = A x M
• description of light microscopes

  study living cells

  have low magnification/resolution

  pass light through specimen
• description of electron microscopes

  study non-living cells

  high resolution/magnification

  see smaller things in detail (subcellular structures)
• microscopes practical

  1. peel skin from underside of an onion
  2. press onto slide, making sure its flat with no air bubbles
  3. stain with iodine and cover with a coverslip
  4. look through the microscope (lowest objective lens first) and focus using coarse focus wheel
• what are enzymes

  biological catalysts which speeds up reactions without being used up
• what do enzymes reduce and why

  need for high temperatures, as they speed up the reaction
• how does an enzyme catalyse the reaction

  the active site joins onto the substrate

  lock and key mechanism

  high specifity for substrate (only binds with one substrate)
• temperature and enzymes

  they work best at an optimum temperature

  lower temperature means a slower reaction

  higher temperature means that the enzyme denatures and the shape of the active site changes and doesn't fit the substrate
• enzymes and pH

  too high/too low means that the bonds break and the enzyme denatures

  optimum pH is usually pH 7

  pepsin (breaks down protein in stomach) has an optimum at pH 2
• enzymes and substrate concentration

  higher substrate conc = faster reaction as it's more likely for an active site to bind with a substrate

  only up until a certain point as all the active sites are full, so even if there's more substrate, it won't make a difference as it has nothing to bind to
• rate of reaction

  = 1000 / time

  = change / time
• carbohydrates

  starch is broken down by amylase into simple sugars
• proteins

  proteins are broken down by protease into amino acids
• lipids


  lipids are broken down by lipase into fatty acids and glycerol
• test for sugars (benedicts reagent)

  add benedicts to solution and heat in a water bath to 75 degrees

  positive test = coloured precipitate

  blue - green - yellow- orange - brick red (lots of reducing sugars if red)
• test for starch (iodine solution)


  add iodine solution

  positive = blue-black

  negative = stays brown-orange
• test for lipids (emulsion test)


  add ethanol to solution, shake until dissolved and pour into water

  positive = milky emulsion

  the more lipid, the more noticable the emulsion