Biology 1

• What do eukaryotic cells contain?


  Cell membrane

  cytoplasm

  genetic material enclosed in a nucleus

  e.g plant/animal cells
• What do prokaryotic cells contain?

  Cytoplasm

  cell membrane surrounded by a cell wall

  genetic material is a single dna loop

  could also be smal rings of dna called plasmids

  flagellum
• Mitochondria


  • Most reactions for aerobic respiration occur here
  • Transporting energy to the cell
• Cytoplasm


  Gel-like substance where chemical reactions happen and containing enzymes
• Nucleus

  Contains genetic material

  Controlling cell activity
• Ribosomes


  Protein synthesis
• Cell membrane 


  Holds the cell together

  contols what goes in and out
• Chloroplasts(plant cells)

  • Where photosynthesis occurs to make food for the plant
  • Contain a green substance called chlorophyll to absorb light needed for photosynthesis
• Cell wall(plant cells)


  • Rigid structure made of cellulose
  • Strengthens and supports the cell
• Vacuole(plant cells)


  Permanent structure that contains a solution of sugars and salts(cell sap)
• Light microscopes


  • Lower magnification
  • Lower resolution: can distinguish between organelles
  • Light passes through the specimen
  • Can view living cells/organisms
• Ligh microscopes (advantages)

  • Can study living cells
  • Cheap
  • Portable
• Light microscopes(disadvantages)

  • Lower magnification
  • Lower resolution
• Electron microscope


  Device that uses a beam of electrons to create an image of the specimen
• How electron microscope works

  Electrons pass through the specimen
• Electron microscope


  • Higher magnification
  • Specimen must be dead
  • Higher resolution to distinguish between internal structures of organelles
• Advantages of electron microscope


  • Higher magnification
  • Higher resolution
• Disadvantages of electron microscope


  • Can't study living cells
  • Expensive
  • Not portable
• Stem cells


  Undifferentiated cells
• Embryonic stem cells


  • Can turn into any cell
  • Can divide to produce more differentiated cells that can differentiate into different types of cells depending on instructions given
• Stem cells are found in early human embryos
• Adult stem cells


  • Can only turn into certain cells such as blood cells
  • Only found in certain places such as bone marrow
• Stem cells from embryos and bone marrow

  1. Can be grown in a lab to produce clones

  2. Can be differentiated into specialised cells for medicine/research
• Stem cells ( adult stem cell uses)

  Cells from bone marrows of a healthy person that can replace faulty blood cells
• Embryonic stem cells (uses)

  Can make insulin-producing cells for people with diabetes or nerve cells for people who are paralysed
• Therapeutic cloning

  1. An embryo could be made to have the same genetic information as a patient

  2. Stem cells produced would contain the same gene and wouldn't be rejected by the patient's body
• Risks of stem cells grown in a lab: could be contaminated with a virus that could pass to the patient making them sick
• Some people may have ethical or religious objections to stem cell treatments
• Reasons for stem cell use

  • People think curing people who are alive and suffering is more important
  • Embryos uses are unwanted from fertility clinics so would be destroyed anyway
• Reasons against stem cell use

  • People feel embryos are a potential human life
  • People think scientists should find other sources of stem cells
• Plant Stem cells

  Found in meristems
• Throughout a plant's life, stem cells can differentiate into any cell
• Stem cells(plant)


  • They can be used to produce clones of planes quiciely + cheaply
  • Used to grow plants of rare species: prevents them being wiped out
  • Can be used to grow crops of identical plants with desired features such as disease resistance
• Differentiation


  The process by which a cell changes to become specialised for its job
• Differentiation


  • Cells develop different subcellular structures
  • Cells turn into different types of cells
  • Allows cells to carry out specific functions
• Differentiation usually occurs as an organism develops
• Most animal cells lose the ability to differentiate at an early stage after becoming specialised
• Plant cells don't lose the ability to differentiate
• Cells that differentiate in mature animals


  Are used for repairing or replacing cells such as skin or blood cells
• Undifferentiated cells


  Stem cells