Topic 4

• Genome - complete set of genes in a cell
• Proteome - full range of proteins that a cell can produce
• RNA :

  • single strand polymer
  • Aadenine, cytosine, guanine, and uracil
  • used In protein synthesis
• RNA has ribose, DNA has deoxyribose
• Transcription is the forming of mRNA
• mRNA is used to transfer the DNA code into the cytoplasm from nucleus. Does this by leaving the nuclear pores. once in the cytoplasm, mRNA associates with the ribosomes. mRNA is used to determine the sequence of amino acids during protein synthesis. mRNA is easily broken down and only exists when it is needed to make a protein
• The sequence of nucleotides in the mRNA is referred to as the genetic code
• How mRNA Is made (6)

  • dna helicase breaks hydrogen bonds to made template Strands
  • one of the DNA strands will act as a template
  • RNA nucleotides join to form complimentary base pairs, following base pair rule (A-U,C-G)
  • RNA polymerase joins the RNA nucleotides together
  • By making phosphodiester bonds
  • Pre mRNA spliced (removes introns) to produce mature mRNA
• tRNA structure:

  • small molecule (80 nucleotides)
  • single strand and folded into clover shape
  • each tRNA can carry a different amino acid
  • 3 bases at the opposite end of tRNA are called anti codon
  • each amino acid has a different anti codon
  • the anti codon pairs with the complimentary codon on the mRNA
• rRNA ( ribosomal RNA) is the type of RNA that makes up the bulk of ribosomes
• Splicing- pre mRNA to mRNA:

  • the gene contain exons and introns which are both transcribed
  • enzymes (spliceososmes) remove the introns and splice together the exons
  • now it is mature mRNA and will leave the nucleus through nuclear pore to cytoplasm, then associates with the ribosomes
• Exons - coding element of gene
• Introns - non coding element of gene
• Mutation - change in structure of dna
• Mutagenic agents include:

  • radiation
  • chemicals
  • infections
• Substitution - one base pair substituted for another
• Deletion- one base pair removed
• Addition- one base pair is added