BIO P1

• Eukaryotic cells

  Plant & animal cells
• Prokaryotic cells

  Bacterial cells
• Subcellular structures NOT in animal cells

  Cellulose cell wall, permanent vacuole, chloroplasts
• subcellular structures specific to Bacterial cells

  Strands of DNA, Plasmids, flagella, slime capsule
• Magnification of a microscope

  eyepiece x objective lense
• Magnification of image

  Image size / actual object
• Diffusion

  The net movement of particles from an area of higher concentration to an area of lower concentration
• Osmosis

  The movement of water molecules from a dilute solution to a concentrated solution across a partially permeable membrane
• Active transport

  the movement of particles against the concentration gradient. (Requires energy from respiration)
• Aseptic techniques

  • Sterilise inoculating loop over a Bunsen burner
  • Partially seal lid to prevent contamination from microorganisms in the air
  • incubate at 25 degrees to prevent the uncontrolled growth of harmful bacteria
  • store agar jelly plate upside to stop drops of condensation falling on agar surface
• Differentiation

  The process by which cells develop specific structures and becomes specialised
• Different stem cells:

  • Adult stem cells (bone marrow)
  • Embryonic stem cells
  • Meristem stem cells (roots of plants)
• Uses of Meristem stem cells

  • Produce clones of plants quickly and cheaply
  • Grow more plants of a rare species or plants with desired with characteristics
  • Can become any type of plant cell
• Animal stem cell uses

  • Can be used in medicine to treat diseases such as paralysis and diabetes
  • Adult stem cells in the bone marrow can only differentiate into similar cells (e.g WBC, RBC )
  • Embryonic stem cells can differentiate into any type of cell but have ethical issues.
• The Cell Cycle

  1. DNA replicates, subcellular structures increase as as Cell growth occurs.
  2. One set of chromosomes is pulled to each end of the cell.
  3. The cytoplasm and cell membrane divide to form 2 genetically identical diploid cells.
• Mitosis

  Asexual reproduction in cells that allows multicellular organisms to grow or replace cells that have been damaged.
• Uses of therapeutic cloning

  • Adult stem cell transfer would not be rejected as the stem cells would be genetically identical to the patient.
  • An embryo could be made with the same genes as the patient.
• Risk of therapeutic cloning

  • Stem cells from the lab could get a virus which could be transferred to the patient.
  • difficulty in finding suitable stem cell donors
  • Source of embryonic stem cells is IVF which raises ethical issues.
• Small intestine exchange surfaces

  • Villi & microvilli (Increase SA)
  • Once cell thick wall (ensures a short diffusion path)
  • Good blood supply/capillary network (maintains the conc. gradient)
  • Many mitochondria ( releases energy from respiration fro active transport)
• Gas exchange in the lungs

  • Alveoli (large SA)
  • Alveoli have one cell thick wall (ensures short diffusion path)
  • Alveoli walls are moist (allowing the gases to dissolve)
  • Good blood supply (maintain conc. Gradient)
• Preparing cells for viewing under microscope.

  1. Use tweezers to peel a thin layer of epidermal tissue from the onion sample. (cotton swab for cheek cells)
  2. Add a drop of water to a clean slide and place the tissue into the water on the slide
  3. Add iodine to stain the cell (Methylene blue for cheek cells) and place a cover slip on top of the specimen.
• Using a microscope

  1. Clip the slide onto the stage initially starting on the lowest powered objective lens
  2. Use the coarse adjustment knob to move the stage up, just under the objective lens
  3. Look down the eyepiece lens and use the fine-adjustment knob to make the image clearer
  4. Change the objective lense to the desired magnification.
• The effect of salt solutions on plant cells (RP)

  1. Use a cork borer to cut identical potato cylinders and record each cylinders mass on a balance
  2. Place each cylinder into a different sugar solution for 40 minutes
  3. Remove the potato and record its new mass
  4. Calculate percentage changes in mass for all potato cylinders.
• Effect of pH on amylase (RP)

  1. Place one drop of iodine solution into each well on a spotting tile
  2. Take 3 test tubes; 2cm3 starch solution, amylase solution and pH buffer solution
  3. Place them in a water bath at 30 degrees and leave for 10 mins
  4. Combine solutions and mix w/ stirring rod. Return to water bath and start stopwatch.
  5. After 30s transfer 1 drop of the solution to a well in the spotting tile.
  6. iodine should turn blue black to show starch is present
  7. now take a sample every 30s until iodine remains orange
• Factors effecting enzyme action

  pH

  Temperature

  above or below the optimum level, the active site begins to denature.
• Enzymes

  biological catalysts- speed up the breakdown of larger molecules into smaller molecules.

  They have an active site specific to the substrate
• Protein food test

  + biuret solution

  turns purple
• Starch food test

  + iodine solution

  turns blue-black
• Sugar food test

  grind food and mic w/ water

  filter & add benedict's solution

  heat in water bath

  turns red/yellow/green depending on conc. of sugar
• Lipids food test

  +ethanol and water

  shake

  forms milky white emulsion
• Bile

  Produced in the liver, stored in the gall bladder

  released into the small intestine, where it emulsifies lipids and neutralises stomach acid
• Circulatory system

  from body-> right side of heart via vena cava-> right atrium-> right ventricle-> pulmonary artery ->lungs ->pulmonary vein->left atrium-> left ventricle-> rest of the body via the Aorta.
• Arteries

  carry blood away from the heart at high pressures

  • thick muscular and elastic walls (withstand pressures)
  • narrow lumen (maintain pressure)
• Veins

  carry blood towards the heart at low pressures

  • valves (prevents the back flow of blood)
  • large lumen ( lowers resistance to flow of blood)
• Leaky valves

  The valves do not close fully, which allows the backflow of blood. This forces your heart to do more work pumping the same vol of blood, creating a strain on the heart.
• Cardiovascular disease

  coronary arteries have a build up of fatty material and so the lumen becomes narrow.
• Stents

  Tube inside artery which widens the lumen.

  CONS; surgery lasts a long time & could result in blood clots near stent.
• Statins

  changes the balance of cholesterol. Taken regularly but could have side effects.
• Factors effecting rate of transpiration

  temp, light intensity, humidity and air flow.
• Viral infections

  • TMV
  • HIV
  • Measles