nucleotides and nucleic acids

• single ringed nitrogenous bases and name

  T (U) and C (pyrimidines)
• double ringed nitrogenous bases and name

  A and G (purines)
• why does A always pair with T?

  because they both make 2 hydrogen bonds
• why does C always pair with G?

  because they make three hydrogen bonds
• what bond forms between polynucleotides

  phosphodiester
• single ringed bases always pair with double ringed bases.. true or false?

  true
• DNA replication enzymes

  DNA helicase - breaks H+ bonds of polynucleotide strands splitting them in half

  DNA polymerase - catalyses phospodiester bonds between new polynucleotides
• what is makes the end a 3' end or a 5' end

  5' end has phosphate , 3' end doesn't
• DNA replication process


  - DNA helicase breaks H+ bonds of 2 polynucleotide strands splitting them in half

  - exposed strand is template for complementary free nucleotides that line up

  - DNA polymerase - catalyses phospodiester bonds between new polynucleotides

  - works from 3' end to 5' end (other strand okizaki fragments)
• why is dna replication semi conservative


  because it has one old parent strand and one new daughter strand
• obtaining dna from kiwi practical

  make solution: crush kiwi, add detergent and salt

  add solution to ethanol or alcohol: to make white dna precipitate
• why do we crush and add detergent to the kiwi in the mixture


  mechanically breaks down cell wall and mem and chemically
• why do we add salt to the kiwi in the mixture

  neutralise the DNA charge and make the molecule less hydrophilic
• what is a codon

  3 bases code for 1 amino acid
• what is a degenerate code


  when codes are different but code for same amino acid
• tRNA structure


  single stranded folded into a weird shape with a point of attachment for the amino acid and a anticodon loop
• 3 stages of protein synthesis

  transcription, splicing and translation
• transcription


  - DNA Helicase breaks H bonds

  - one of the DNA strands (the sense strand) acts as template for complementary RNA nucleotides

  - RNA polymerase moves along new strand joining together to make mRNA single strand of DNA that stops when stop codon is reached

  - old strand joins old helix again
• splicing


  introns (non functional parts that don't code for amino acids are removed) and extrons (useful parts) are left
• Translation


  mRNA attaches to ribosome

  tRNA with the complementary amino acid on it attaches to codon on mRNA

  ribosomal RNA holds mRNA and tRNA together until peptide bonds forms between amino acids

  tRNA are released back into cytoplasm

  ribosome continues along mRNA until stop codon
• how do random mutations occur

  incorrect base means sequence is changed
• reaction for ATP including ADP

  ATP through hydrolysis goes to ADP + Inorganic phosphate

  ADP + Inorganic phosphate through condensation reaction goes to ATP
• structure of ATP


  3 inorganic phosphates, a ribose sugar and adenine
• structure of ADP

  2 inorganic phosphates, a ribose sugar and adenine
• why is it good ATP is a small molecule

  easy to move and transport
• why is it good ATP is water soluble

  processes needing ATP often happen in water
• why is it good ATP releases energy in small quantities

  matches need of cell so no waste
• why is it good ATP is released in a one step reaction

  energy can be made quick
• uses of ATP

  active transport

  metabolic reactions

  muscle contraction

  synthesis (proteins and lipids)
• a base name


  Adenine
• c base name

  Cytosine
• t base name

  Thymine
• U base name

  uracil
• G base name

  Guanine
• A gene is a section of DNA that codes for the production of a

  polypeptide