2.3:NUCLEOTIDES+NUCLEIC ACIDS

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Cards (64)

  • nucleotides are the monomers from which nucleic acids like DNA and RNA are formed
  • nucleic acids contain nitrogenous bases , phosphate group and a pentose sugar
  • the nitrogenous bases are categorised by their ring structures and organised into purines and pyrimidines
  • purines have a 2 carbon ring structure and are adenine and guanine
  • pyrimidines have a single carbon ring structure and are cytosine, thymine and uracil
  • guanine is always paired with cytosine
  • adenine is always paired with thymine or uracil
  • uracil is only found in RNA
  • deoxyribose sugar is found in DNA
  • ribose sugar in RNA
  • purines and pyrimidines bases are always opposite each other in dna maintaining order
  • both RNA and DNA undergo condensation reaction forming phosphodiester bonds
  • the phosphodiester bond between adjacent nucleotides form the polymer polynucluotides
  • phosphodiester bonds are very strong covalent bonds
  • DNA codes for the sequence of amino acids in primary structure of protein which determines the 3d shape of tertiary structure
  • polymer forms a double helix made of two antiparelel strands joined together by hydrogen bonds
  • DNA has a stable structure due to the phosphodiester bonds that form between nucleotides
  • weak hydrogen bonds between bases makes it easier for strands to separate for DNA replication
  • DNA is a large molecule so can carry a lot of information
  • DNA can be extracted out of cell using the method of precipitation
  • RNA is single-stranded, whereas DNA is double-stranded.
  • three types of RNA are tRNA rRNA and mRNA
  • rRNA forms part of the ribosome which is where proteins are made
  • mRNA leaves the nucleus via nuclear pores and carries genetic code to ribosomes in cytoplasm
  • mRNA is single stranded and every 3 bases in the sequence codes for a specific amino acid these are called codons
  • tRNA has an anticodon that matches with the codon on mRNA so it brings the correct amino acid to the ribosome
  • tRNA is single stranded but folds into clove leaf like structure held in place by hydrogen bonds
  • tRNA carries specific amino acids to ribosomes this is determined by the 3 bases on tRNA called anticodons
  • DNA replication is described as semi conservative as one single strand of DNA is conserved and one entire new strand is created from new nucleotides
  • copying errors can occur but they are random and they result in the change in DNA sequence this is called a mutation
  • DNA replication occurs in s phase in interphase of cell cycle
  • the genetic code has 3 features which are that it is degenerate universal and non overlapping
  • degenerate means that the amino acids are coded for by more that one triplet of bases of DNA
  • the genetic code being degenerate is an advantage as even if a mutation occurs changing a base in triplets still codes for the same amino acid meaning no impact on final sequence of amino acids
  • universal means the triplet of bases codes for same amino acids in all organisms
  • the genetic code being universal is an advantage as it means we are able to remove a human gene and insert into the plasmids of a bacterium
  • on overlapping means each base in a gene is only part of one triplet base that codes for one amino acids
  • the genetic code being non overlapping is an advanatage as if there was a mutation the mutation will only affect one codon
  • protein synthesis is when proteins are being created on ribosomes on RER
  • protein synthesis occurs in two stages translation and transcription