biology

• what is cell differentiation


  Process by which a cell changes to become specialised for its job
• what are stem cells 


  cells that can differentiate once early on or have the ability to differentiate their whole life
• Embryonic stem cells


  -Form when an egg and sperm cells fuse to form a zygote

  -They change into any cell in the body

  -Can potentially be used to replace insulin-producing cells in people who suffer from diabetes
• Adult stem cells

  • found in bone marrow they can form many types of cells including blood cells
• Advantages of stem cells 


  -Replace damaged cells

  -Bone marrow transplants

  -No rejections

  -Can allow testing of millions
• Disadvantages of stem cells 


  -Ethical issues

  -Can create long-term affects if they go wrong

  -Mutations

  -Difficult to find suitable stem cells
• Test for Starch


  Iodine solution

  If starch is present the solution will turn blue or black

  If starch is not present the solution will stay brown
• Test for protein


  Biuret solution in test tube

  If there is a protein present the solution will turn purple

  If there is no protein present the solution will stay blue
• Test for Fat 


  Ethanol solution in distilled water

  If fat is present a milky white emulsion will form

  If fat is not present then the solution will remain colourless
• Test for Glucose


  Benedict's solution- in a hot water bath

  If glucose is present the solution will turn brick red

  If glucose is not present then then solution will remain blue
• What are enzymes made up of


  All protein molecules and they are all made up of chains of amino acids
• What do enzymes do 


  They are biological catalysts which have a unique shape which is shaped to the active site where the substrate combines to
• what is meant by a biological catalyst 


  a substance that increases the rate of reaction without being used up
• why don't enzymes get used up in the reactions they catalyse


  because they are not reactants
• Lock and Key theory 


  -The shape of the substrate is complementary to the shape of the active site so when they bond it forms an enzyme-substrate complex

  -Once bound the reaction takes place and the products are released from the surface of the enzyme
• Lock and Key theory

  Diagram