1B.1 DNA and RNA

• what sugar is present in RNA?

  ribose.
• is DNA long or short?

  long.
• what is the complimentary base to A and how many hydrogen bonds join them?

  A bonds to T with two hydrogen bonds.
• what is the structure of DNA?

  double helix.
• what is the function of RNA?

  protein synthesis - transfers genetic information from DNA to ribosomes and provides the amino acids to create new strands of DNA.
• what are the bases in DNA?

  adenine, thymine, guanine, cytosine.
• what is the function of DNA?

  store genetic information.
• is RNA double or single stranded?


  single.
• what is the complimentary base to C and how many hydrogen bonds join them?

  C bonds to G with three hydrogen bonds.
• how is the double helix structure of DNA formed?


  two DNA strands join by hydrogen bonds between complimentary bases, and the two anti parallel strands twist to form the double helix.
• what are the components of DNA and RNA?

  phosphate group, pentose sugar, base.
• what are the bases in RNA?

  adenine, uracil, guanine, cytosine.
• is DNA double or single stranded?

  double.
• DNA and RNA are polynucleotides, what does this mean?

  they are made up of long chains of nucleotides.
• what sugar is present in DNA?

  deoxyribose.
• is RNA long or short?

  relatively short.
• how are DNA and RNA formed?

  condensation reactions between phosphate and sugar forming a phosphodiester bond.
• Describe the structure of DNA.

  Polymer of nucleotides

  each nucleotide formed from deoxyribose, phosphate, organic nitrogen base

  phosphodiester bones

  hydorgen bonds between bases
• how do phosphodiester bonds form between nucleotides in DNA

  condensation reaction between phosphate and deoxyribose

  releases a molecule of water

  catalysed by DNA polymerase
• what is the role of DNA helicase

  breaks hydrogen bonds between bases which seperates the strands of DNA allowing them to act as templates
• what is the role of DNA polymerase

  joins adjacent nucleotides by catalysing the condensation reaction which results in phosphodiester bonds and the release of a molecule of water
• what are the two roles of the single stranded DNA fragments

  acts as a template to attract bases

  determines the order of bases
• Give two features of DNA and explain how each one is important in the semi-conservative replication of DNA.

  weak hydrogen bonds which are easily broken to allow the strands to separate

  complimentary base pairs allows accurate replication
• why are opposite strands formed in different ways during DNA replication

  DNA has antiparrallel strands with 3’ and 5’ at opposite ends, DNA polymerase is an enzyme with a specific active site shape, this is only complimentary to one end of the nucleotides.
• give two ways in which ATP is a suitable energy source for cells to use.

  phosphorylates other compounds

  can be rapidly resynthesised
• how is ATP resythesised

  condensation reaction between ADP + Pi catalysed by ATP synthase during respiration