cell organelles

• bacterial DNA

  circular with no nucelar membrane
• image size formula


  actual size x magnification
• actual size formula

  image size/magnification
• magnification formula

  image size/actual size
• um to mm


  divide by 1000
• mm to um


  multiply by 1000
• describe how DNA is organised in a bacterial cell

  large circular DNA

  which is not associated with any histone proteins

  there are small, several plasmids which are located in the cytoplasm
• formation of extracellular enzymes in cell

  vesicles fuse with the golgi apparatus

  inside golgi apparatus modification of proteins occurs

  proteins/enzymes are then packaged into secretory vesicles

  these vesicles then fuse with the cell surface membrane

  and release enzymes and proteins

  such as extracellular enzymes via exocytosis
• desribe what happens to lysosome once their contents have been digested

  lysosomes fuse with the cell surface membrane

  their contents are then released from the cell via exocytosis
• features of eukaryotic organisms

  membrane bound organelles

  contains nucleus, mitochondria, golgi, SER , RER

  80s ribosome

  linear DNA associated with histone proteins

  does not contain plasmids in the cytoplasm
• features of prokaryotic cells

  presence of cell wall

  circular DNA/plasmids

  small 70s ribosomes

  pili / flagellum

  capsule/mesosomes
• role of centriole

  spindle organisation
• explain why the nucleus cannot be observed at the end of prophase in a eukaryotic cell

  because the nuclear membrane is broken down

  because the DNA is coiled or condensed into individual chromosomes
• functions of the golgi apparatus

  modifies proteins

  forms vesicles

  removes some water from the protein
• protein synthesis in eukaryotic cells occurs in

  80s ribosomes on the endoplasmic reticulum
• describe what happens to proteins following the process of translation until they are released from the cell


  -folded in the rER

  • packaged into vesicles
  • modified in the Golgi apparatus
  • released from the cell via exocytosis from a lysosome
• explain why enzymes that are incorrectly folded cannot carry out their function

  -tertiary structure is different (when incorrectly folded)

  • active site of enzyme will not fit with substrate
  • will not form an enzyme-substrate complex
  • therefore will not catalyse the reaction and enzyme will be incorrectly folded