differentiation and specialisation

• cells specialise by undergoing a process called differentiation.
• Differentiation

  As multicellular organisms develop, their cells become specialised to carry out a particular job. This makes the organism function more efficiently.
• Types of cells you are made up of

  • Skin cells
  • Muscle cells
  • Blood cells
  • Nerve cells
  • Bone cells
  • Liver cells
• Light microscope

  • Uses light
  • Focuses using lenses
  • 1500x magnification
  • 200nm resolution
  • Can view living or dead samples
  • Cheap and portable
  • Easy to use
• Electron microscope


  • Uses electrons
  • Focuses using magnets
  • Very high magnification (30,000x +)
  • Very high resolution (0.2nm)
  • Can only view dead samples (in a vacuum)
  • Expensive
  • Hard to use
• Specialised cells


  • Red blood cells
  • Ciliated epithelial cells
  • Fat cells
  • Sperm cells
  • Palisade mesophyll cells
  • Root hair cells
• Red blood cells


  • Transport oxygen around the body
  • Biconcave discs - increases their surface area, speeding up diffusion of oxygen and carbon dioxide
  • Contain red pigment haemoglobin which binds to oxygen
  • No nucleus - more space for haemoglobin
• Ciliated epithelial cells


  • Found in your airways
  • Cilia are tiny hairs on top of the cells
  • Work with goblet cells (which produce sticky mucus) to sweep mucus away from the lungs, preventing infection
• Fat cells


  • Store fat for energy, insulation and protection (around your organs)
  • Contain very little cytoplasm
  • Have few mitochondria
  • Can expand up to 1000x their original size
• Sperm cells


  • Transfer genetic material from the male to the ovum (egg)
  • Has an acrosome which contains digestive enzymes to break into the ovum
  • Many mitochondria to provide energy for movement
  • Has a long flagellum (tail) to propel the sperm along
• Palisade mesophyll cells


  • Specialised for carrying out photosynthesis
  • Found near upper surface of the leaf and contain many tightly packed chloroplasts to absorb sunlight
  • Regular shape means many cells can be closely packed to maximise the light absorbed
• Root hair cells


  • Absorbs water and minerals from the soil
  • Thin membrane
  • Large surface area for quicker absorption
• Why is a red blood cell better at carrying oxygen than a normal body cell?

  • It has no nucleus and a biconcave shape, this gives more space for carrying oxygen
  • It has haemoglobin, which can bind to oxygen
• What would happen if someone had normal cells instead of red blood cells?

  Not enough blood would get around the body. This would lead to less respiration and the person feeling tired and like they have less energy
• Stem Cell


  A cell that hasn't yet become specialised
• Stem cells

  • They are able to turn into many different cell types
• Where stem cells are found in animals

  • Embryonic stem cells - found in embryos
  • Adult stem cells - found in tissues such as the brain, bone marrow, skin and liver
• Embryonic stem cells


  • Have the ability to differentiate into all cell types
• Adult stem cells

  • Can differentiate into some but not all types of cell
• Where stem cells are found in plants

  • Meristems - in the root and shoot tips, and buds
  • These stem cells have thin cell walls and small vacuoles compared to normal plant cells
• Uses of Stem Cells

  • Spinal cord injury
  • Diabetes
  • Heart disease
  • Parkinson's disease
  • Alzheimer's disease
• differentiation is the process where cells become more specialised to perform specific functions
• interphase is when the cell grows and replicates its DNA ready for division.
• specialisation is when an organism has one or more organs that carry out a particular function
• what is the stage in the cell cycle after the chromosomes are split apart to opposite ends of the cell by cell fibres?

  membranes form around each set of chromosomes forming the nuclei of the two cells. The cytoplasm divides to form the two new cells.
• why must DNA replication happen before mitosis?

  so that there will be one copy of DNA for each new cell produced by mitosis.
• in terms of function, how adult stem cells and embryonic stem cells differ?

  embryonic - growth and development

  adult - replacing damaged cells.
• the shoot tip of a plant can be used to grow a whole plants, explain how this process can generate whole plants.

  the shoot tips are made of meristem tissue. the meristem tissue produces unspecialised cells that can divide and form into any type of cell. Therefore the cells in the shoot tip can form any type of cell in a plant, so they can generate the whole plant too.