8a. Nucleic acids

• What is DNA?

  Deoxyribonucleic acid
• What is DNA made up of

  A deoxyribose sugar

  base

  phosphate group
• What type of reaction is used to join nucleotides

  Condensation
• What are purines

  Bigger bases (guanine and adenine)
• What are pyrimidines

  Smaller bases (thymine and cytosine)
• What does DNA form

  two anti parallel chains that form a double helix.
• How many bonds does adenine form with thymine

  2
• How many bonds does cytosine from with guanine

  3
• How does the structure of DNA relate to its function

  Double helix - stable and strong

  complementary base pairs allows it to replicate itself

  compact - store lots of genetic material
• What is RNA made of 


  Ribose sugar

  phosphate

  bases
• What is thymine replaced with in RNA

  uracil
• How does DNA replicate

  DNA helicase hydrolyses hydrogen bonds between the bases. Strands separate and act as template. DNA nucleotides complementary base pair and DNA polymerase joins nucleotides together to form phosphodiester bonds
• What was the evidence for semi conservative replication

  bacteria E.coli were labelled with heavy 15N. Then transferred to a medium containing the light isotope 14N. after periods of time samples were centrifuged.
• What is ATP

  Adenosine triphosphate

  made up of adenine and three phosphate and ribose sigar
• How is ATP synthesised

  Addition of ADP to an inorganic phosphate. Catalysed by atp synthase
• How is atp broken down

  Useful energy is stored in the bond between the last two phosphates. The covalent bond is unstable, catalysed by atp hydrolase.
• What is ATP used for

  Active transport

  exocytosis

  movement of muscle cells
• Why is atp an immediate energy source

  Instability of phosphate bonds
• Why is atp useful

  Breakdown is a single reaction so its immediate

  soluble