enzymes + dna

• ATP - Adenine TriPhosphate
• nucleus - contains genetic material and controls cell activities
• cytoplasm - a jelly-like substance where most chemical reactions happen
• mitochondria - where respiration occurs and contains enzymes
• ribosomes - where proteins are made
• cell membrane - controls what goes in and out of the cell by providing a selectively permeable barrier. also contain receptor molecules used in cell communication e.g. by hormones
• rigid cell wall - made of cellulose, provides support for the cell
• chloroplasts - where photosynthesis occurs. contain a green pigment named chlorophyll.
• chromosomal dna - floats free in the cytoplasm
• plasmids - small loops of extra DNA
• cell membrane - controls what goes in and out of the cell, supported by a cell wall.
• Electron Microscopes

  • higher magnification and resolution
  • expensive
  • training required
  • can only be used to look at dead specimen
  • can see sub-cellular structures
• Light Microscopes

  • cheaper
  • no training required
  • portable, easy to move
  • can see both living and dead specimen
  • less resolution and magnification
• staining cells - allows us to see sub-cellular structures if the cell is see-through or colourless.
• Magnification = Image size / Real size
• I = AM
• total magnification = eyepiece lens magnification x objective lens magnification
• DNA - double helix structure. made up of nucleotides joined together, making DNA a polymer and the nucleotides are monomers
• A (adenine) pairs with T (thymine)
• C (cytosine) pairs with G (guanine)
• Complementary Base Pairing

  • A with T
  • C with G
• Nucleotides contain a sugar-phosphate backbone and a base (either A,G,C or T).

  
• DNA is a polymer made up of a chain of nucleotides (monomers)
• Carbohydrates are made up of simple sugars e.g. glucose and fructose. These monomers can be joined to make polymers e.g. starch and glycogen.
• Carbohydrates are broken down by enzymes in the mouth and small intestine
• Proteins are made up of amino acids. Proteins are broken down by enzymes in the stomach and small intestine
• Lipids are made up of fatty acids and glycerol. They are NOT polymers. They are broken down by enzymes in the small intestine.
• Testing for Lipids


  Emulsion test, the test tube will have a cloudy-white emulsions if lipids are present. Shake the substance with ethanol in a test tube then pour into water.
• Testing for Starch


  Iodine:

  add iodine to the sample.

  if starch is present, the sample changes from browny-orange to blue-black.
• Test for Sugars


  add Benedict's solution (blue) to a sample and heat it in a water bath set at 75 degrees.

  if there is a high concentration of sugar, it will turn brick red.

  blue --> green --> yellow --> orange --> brick-red
• DNA - deoxyribo nucleic acid
• DNA is the genetic information found in the nucleus of a cell ; it is a chemical code. DNA is a polymer made of nucleotides that consist of a sugar, a phosphate and a base.
• Transcription

  the process of a gene's DNA code being copied to make a messenger RNA (mRNA) molecule.

  1. mRNA unzips the double helix.
  2. then the mRNA copies the code from the template strand. The original strand is then zipped back up.
  3. it is small enough to leave the nucleus, and travels to the ribosome where translation occurs.
• Translation

  at the ribosome, the code from the mRNA is used to join a codon with amino acids attached to them. tRNA is that brings in the correct amino acid to join with the chain.