Nucelotides

• Nucleic acids contain carbon, hydrogen, nitrogen, oxygen, and phosphorus.
• Nucleotides are made up of a pentose monosaccharide, an inorganic phosphate group, and a nitrogenous base.
• The pentose sugar in DNA is deoxyribose - a sugar with one fewer oxygen atoms than ribose.
• DNA has four different bases: adenine, thymine, guanine, and cytosine.
• Adenine pairs with thymine via two hydrogen bonds. Guanine pairs with cytosine via three hydrogen bonds.
• Pyrimidines

  Smaller organic bases, which contain single carbon ring structures - thymine and cytosine.
• Purine

  The lager organic bases, which contain double carbon ring structures - adenine and guanine.
• Two Apples in a Tree, Three Cars in a Garage
• The hydrogen bonds between bases pairs help to maintain a constant distance between DNA backbones.
• DNA strands are anti-parallel, so one end has a phosphate group (5') and the other has a hydroxyl group (3').
• Phosphodiester bonds form between the phosphate group at the C5 of the pentose sugar and the hydroxyl group of an adjacent nucleotide.
• The two strands of DNA are arranged so that they run in opposite directions, called being anti-parallel.
• RNA transfers genetic information from DNA to the proteins that make up the enzymes and tissues of the body.
• DNA is a very long molecule, comprising of many hundreds of genes, and is unable to leave the nucleus.
• RNA is single stranded, DNA is double stranded.
• RNA has ribose sugars, DNA has deoxyribose.
• In RNA, uracil replaces thymine.
• Both DNA and RNA have cytosine, guanine and adenine bases.
• Both DNA and RNA form phosphodiester bonds between their sugar and phosphate groups.
• RNA polymers are small enough to leave the nucleus and travel to the ribosome for protein synthesis.
• After protein synthesis, the molecules of RNA are degraded in the cytoplasm. Hydrolysis takes place and nucleotides are released and reused.
• The antisense strand of DNA is used as the template during transcription. The sense strand is not used because it already contains all the information needed by the cell.
• During transcription, mRNA is made from one strand of DNA.
• ADP

  Adenosine diphosphate
• ATP

  Adenosine Triphosphate
• ATP proved energy for chemical reactions in the cell.
• ATP is synthesised from ADP and inorganic phosphate (Pi) using the energy from an energy-releasing reaction, e.g., the break down of glucose in respiration.
• ATP/ADP are phosphorylated nucleotides - a nucleotide with one or more phosphate group added.
• ADP contains adenine, ribose and two phosphate groups.
• ATP contains adenine, ribose and three phosphate groups.
• ADP is phosporylated to form ATP and a phosphate bond is formed.
• Energy is stored in the phosphate bond between inorganic phosphate groups. When this energy is needed by a cell, ATP is broken back down into ADP and an inorganic phosphate group. Energy is released from the phosphate bond broken and is used by the cell.
• Adenosine triphosphate

  
• Adenosine diphosphate

  
• ATP is a universal energy currency.
• Purifying DNA with Precipitate Reactions

  1. Break up cells in sample e.g., with a blender.
  2. Make up a solution of detergent, salt and distilled water.
  3. Add broken up cells to detergent solution and incubate in a water bat hat 60C for 15mins.
  4. Place in an ice bath to cool down. Filter mixture.
  5. Ad protease enzymes to break down proteins, and RNase enzymes to break down RNA.
  6. Slowly add drips of cold ethanol so that it forms a layer on top of the solution.
  7. Leave to form a white precipitate. This is the DNA.
• Protease enzyme breaks down proteins.
• RNase enzyme breaks down RNA.
• DNA helicase breaks the hydrogen bonds between the two strands of DNA and separates ('unzips') them.
• Each original strand of DNA acts as a template for a new strand. Free-floating DNA nucleotides join to the exposed bases on each original complementary base pairing.