DNA & ATP

• Nucleotides


  monomer of a nucleic acid

  made up of - phosphate group, organic base, pentose sugar
• DNA


  deoxyribonucleic acid

  type of nucleic acid

  constructed of 2 polynucelotides
• Phosphate ions in DNA


  create a strong sugar-phosphate backbone along with the deoxyribose sugar

  acts as a binding agent

  creates a PHOSPHODIESTER bond between the SUGAR and PHOSPHAT of ADJACENT nucleotides

  forms a polynucleotide
• Bases within DNA


  ADENINE bonds to THYMINE with 2 HYDROGEN bonds between opposite bases

  
  

  CYTOSINE bonds to GUANINE with 3 hydrogen bonds between opposite bases
• sugar-phosphate and double helix

  provides strength and stability
• sugar phosphate backbone


  protect bases/ protects hydrogen bonds
• long / large molecule


  can store lots of information
• helix / coiled


  compact so can store lots of information in a small place
• base sequence


  codes for amino acids / protein
• double stranded


  for replication, so can occur semi-conservatively bcs both strands can act as template
• weak hydrogen bonds (between bases)


  replication many hydrogen bonds so stable
• RNA structure


  phosphate group

  ribose sugar

  base
• bases


  adenine - uracil

  cytosine - guanine
• types of RNA


  messenger RNA (mRNA)

  transfer RNA (tRNA)

  ribosomal RNA (rRNA) - combined with protein
• Gene


  a sequence of DNA nucleotides that code for a polypeptide
• Intron


  a non coding section of DNA with a gene
• Exon


  Base/ nucleotide/triplet sequence coding for a polypeptide
• semi-conservative replication of DNA


  1. enzyme DNA helicase attaches to the DNA breaking the hydrogen bonds between bases

  2. both polynucleotides act as templates

  3. free individual DNA nucleotides base pair with exposed bases

  4. enzyme DNA polymerase connects nucleotides together by forming the phosphodiester bonds

  5. hydrogen bonds reform

  6. each contains an original strand and a new strand
• 5' (prime) end


  phosphate exposed
• 3' (prime) end


  sugar exposed
• DNA POLYMERASE


  active site is complementary to 3' end ( sugar exposed ) of the template strand and moves in a 3' to 5' direction. polymerase creates a phosphodiester bond within new strand in 5' to 3' end
• ATP - Adenosine triphosphate

  Adenine (base)

  Ribose (sugar)

  Tri-phosphate (3)

  formed from ADP and phosphate catalysed during respiration/photosynthesis
• ADP


  Adenosine Diphosphate + inorganic phosphate
• ATP synthase


  ADP + P = ATP + H2O

  ATP is resynthesised by condensation of ADP + P and is catalysed by enzyme ATPsynthase during photosynthesis or during respiration
• ATP hydrolase


  ATP + H2O = ADP + P

  hydrolysis of ATP to ADP + P is catalysed by enzyme ATPhydrolase
• ATP in biological processes

  1. releases energy in small manageable amounts

  2. single bond between 2P and 3P broken which makes energy available rapidly

  3. phosphorylates (adds phosphate) to make substances more reactive so lowers activation energy

  4. can be rapidly re-synthesised

  5. is not lost/ does not leave cells
• Which processes is ATP used in


  muscle contraction

  protein synthesis

  mitosis

  respiration

  photosynthesis