Features of Genetic Code

• What is a start codon?

  The 3 bases at the start of every gene.
• What is the function of a start codon?

  To initiate translation.
• What is a stop codon?

  The final triplet of bases in DNA that signals a halt to protein synthesis.
• What is the function of a stop codon?

  To mark the end of a polypeptide chain, causing the ribosomes to detach and stop translation.
• How many amino acids does the genetic code have to be able to code for?

  20
• How many combinations is 4^3?

  64
• What is a silent mutation?

  A mutation that has no effect on the final protein.
• Why is genetic code being universal an advantage?

  It allows genetic engineering to be possible.
• Why is genetic code being non-overlapping an advantage?

  If a mutation occurs it will only affect one codon and one amino acid, having a small impact on the final protein structure.
• What are introns?


  Base sequences that don't code for polypeptides.
• How much of DNA is made of introns?

  About 98%.
• Where are introns found?

  In eukaryotic DNA but not prokaryotic DNA or mRNA.
• What happens to introns in mRNA?

  They get spliced out.
• What are exons?


  Base sequences that code for polypeptides.
• What is a genome?


  The complete set of genes within a cell.
• What is the proteome?


  The full range of proteins that a cell is capable of producing.
• What is the difference between the genome of the cell and the proteome of the cell?

  The genome should never change, whereas the proteome of the cell is constantly changing depending on the proteins currently needed.
• What widely varies between organisms?

  The genome.
• What are the 3 features of genetic code?

  Degenerate, universal, and non-overlapping.
• How is genetic code degenerate?


  Some amino acids are coded for by more than one triplet.
• How is genetic code universal?

  Each triplet codes for the same amino acid in all organisms.
• How is genetic code non-overlapping?

  Each DNA base is read once and codes for one amino acid.
• What is a locus?

  A specific point a gene is located on a chromosome.
• What is a codon?


  A sequence of 3 DNA bases that codes for a specific amino acid.
• What is genetic code?

  A sequence of bases that code for amino acids.