B1 - cell biology

• the role of the nucleus


  controls cell activity and contains genetic information
• the role of cytoplasm

  where chemical reactions take plce
• the role of the cell membrane 


  controls the passage of substances in and out of the cell
• the role of mitochondria

  where aerobic respiration takes place
• the role of ribosomes

  where proteins are synthesised (made)
• what do plant cells have that animal cells dont

  • a cell wall
  • a permanent vacuole
  • chloroplasts (containing chlorophyll)
• which type of cells are eukaryotic cells

  • plant
  • animal
• which type of cells are eukaryotic cells

  plant, animal and fungal cells
• what type of cells are prokaryotic

  bacteria
• how is a prokaryotic cell different to a eukaryotic cell

  • the genetic material is not enclosed in a nucleus
  • contains a single DNA loop with one or more rings of DNA called plasmids
  • dont contain mitochondria or chloroplasts
• what is the flagella (bacterial cell)

  tail-like structures that move the bacteria
• which types of cell have a simpler structure

  prokaryotic
• why are plasmids useful to scientists

  they allow genes to be inserted into bacteria in genetic engineering
• light microscope - required practical

  • place a tissue sample on a slide
  • add a few drops of stain
  • lower the coverslip to the tissue
  • place the slide onto the stage and focus on low power
  • change to high power and refocus
  • draw any cells seen
  • add a scale line to the diagram
• equation for magnification

  magnification = size of image / size of real object
• process of mitosis

  • parent cell with two pairs of chromosomes
  • each chromosome replicates itself
  • chromosomes line up along the center of the cell, divide and the copies move to opposite poles
  • each 'daughter' cell has the same amount of chromosomes and the same genes as the parent cell
• why is mitosis important

  • growth and development
  • repairing damaged tissue
  • asexual reproduction
• where can stem cells be found in humans

  • human embryos
  • umbilical cord
  • bone marrow
• use of stem cells

  • used to treat conditions where cells may be damaged
  • therapeutic cloning (replacing damaged cells)
• diffusion

  the movement of particles from an area of high concentration to low concentration.

  • digested food molecules from the small intestine diffuse into the blood
• osmosis

  the diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane
• osmosis - required practical

  • cut some cylinders of potato tissue and measure their mass
  • place the cylinders in different concentrations of sugar solution
  • after 30 mins remove the cylinders and and measure their mass again
• active transport

  • moves substances against a concentration gradient from an area of low concentration to high concentration.
  • energy comes from respiration
  • allows mineral ions to be absorbed into plant root hairs from dilute solutions in soil
  • allows sugar molecules to be absorbed from the gut to the blood