Unit 1: cell biology

• nucleus

  • contains DNA coding for a particular protein needed to build new cells
  • enclosed in a nuclear membrane
• cytoplasm

  • Liquid substance in which chemical reactions occur
  • contains enzymes
  • organelles are found in it
• cell membrane

  • controls what enters and exits cell
• mitochondria

  • where aerobic respiration reactions occur to provide the cell with energy
• ribosomes

  • where protein synthesis occurs
  • found on a structure called the rough endoplasmic reticulum
• chloroplasts

  • where photosynthesis occur providing food for the plant
  • contains chlorophyll pigment which harvests the light needed for photosynthesis
• permanent vacuole

  • contains cell sap made of water and sugars
  • found within cytoplasm
  • improves rigidity of cell
• cell wall

  • made from cellulose in plants (in bacteria cells its made from peptidogylcan)
  • provides strength for cell
• Eukaryotic cells

  • nucleus containing DNA
  • cytoplasm
  • cell membrane
• prokaryotic

  • cell wall
  • cell membrane
  • cytoplasm
  • single circular strand of DNA and plasmids
• sperm cell - specialised to carry the male gamete to the female egg cell for successful reproduction

  • streamlined head and long tail to aid swimming
  • many mitochondria to supply energy
  • the acrosome (tip of head) contain digestive enzymes to break down egg membrane
• nerve cell - specialised to carry electrical impulses around the body

  • long axon to enable impulses to travel far
  • lot of extensions (dendrites) so branched connections can be formed
  • nerve endings have many mitochondria to supply energy to make special transmitter chemicals called neurotransmitters
• muscle cells - specialised to contact quickly

  • special proteins (myosin and actin) slide over each other causing contractions
  • lots of mitochondria
  • store glycogen which is used for respiration
• root hair cells - specialised to take up water by osmosis and mineral ions by active transport from soil

  • large surface area for osmosis
  • large permanent vacuole affects speed of movement of water from the soil to the cell
  • mitochondria to provide energy for active transport
• xylem cells - specialised to transport water and mineral ions from roots to shoots

  • hollow as they contain a chemical called lignin which causes cells to die
  • lignin is deposited in spirals to allow the cells to withstand high pressure
• phloem cells - specialised to carry the products of photosynthesis to all parts of plant

  • cell walls form structures called sieve plates which allow the movement of substances from cell to cell
  • mitochondria to supply energy
• microorganisms are very small so in order for them to be studied they need to grow so are cultured in a medium containing carbohydrates, minerals, proteins and vitamins
• RP1 - microscopy

  • peel off epidermal layer on onion with forceps
  • mount on microscope slide making sure its flat
  • add two drops of iodine to stain cells
  • place coverslip making sure there are no air bubbles
  • remove excess stain
  • place slide on stage of microscope and select low objective
  • focus cells using coarse adjustment knob
  • select higher objective and use fine adjustment knob to focus
  • draw labelled diagram and state magnification
  • repeat 6-9 using preprepared slides of plant or animal cells
• RP2 - microbiology


  1. Spray working area with disinfectant

  2. Wipe dry with paper towel

  3. Mark agar plate with wax pencil (name of bacteria, 3 equal segments, dot in center)

  4. Wash hands

  5. Place different antiseptics on filter paper discs

  6. Lift lid, place discs in center of segments

  7. Tape lid, not too tight

  8. Place agar plate in incubator at 25 degrees for 48 hours upside down

  9. Measure diameter of clear zones

  10. Record results in table

  11. Calculate area of clear zones using formula pir2
• the cell cycle

  1. interphase - the cell grows
  2. mitosis - the chromosomes line up at equator of cell and the cell fibre pull each chromosome to either side
  3. cytokinesis - two identical daughter cells form as cell membrane divides
• Mitosis

  • cell division by mitosis in multicellular organisms is important in their growth and development when replacing damaged cells.
  • It is used during asexual reproduction
• stem cells

  • embryonic - formed when egg and sperm cell fuse to form a zygote
  • adult - found in bone marrow
  • meristems - found in roots and shoots of plants
• Active transport


  The movement of substances from a more dilute solution to a more concentrated solution (against a concentration gradient) with the use of energy from respiration
• Adult stem cell

  A type of stem cell that can form many types of cells
• Agar jelly


  A substance placed in petri dishes which is used to culture microorganisms on
• Cell differentiation


  The process where a cell becomes specialised to its function
• Concentration gradient

  The difference in concentration between two areas
• Diffusion


  The spreading out of the particles of any substance in solution, or particles of a gas, resulting in a net movement from an area of higher concentration to an area of lower concentration
• Magnification


  How much bigger an image appears compared to the original object
• Mitosis


  A type of cell division which produces two genetically identical daughter cells from one parent cell
• Organelle


  A specialised structure found inside a cell
• Osmosis


  The diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane
• Resolution


  The ability to distinguish two different points in a specimen
• Specialised cells


  Cells that are adapted to perform a specific function
• Stem cell


  An undifferentiated cell that can divide to produce many specialised cells of the same type
• Surface area


  The amount of contact an object has with its environment
• Surface area to volume ratio (SA:V)

  The size of the object compared with the amount of area where it contacts its environment
• The cell cycle


  A series of stages preparing the cell for division
• Therapeutic cloning


  Producing an embryo that has the same genes as a patient
• Amylase


  An enzyme produced in the salivary glands and pancreas that breaks carbohydrates down into simple sugars