genetic code

• What are the three key features of the genetic code that need to be learned for AQA Biology?

  Degenerate, universal, and non-overlapping
• What is a start codon?

  The three bases at the start of a gene on DNA
• What does the start codon get copied into on mRNA?

  AUG
• What amino acid does the start codon code for?

  Methionine
• What is a stop codon?

  The final three bases on the end of DNA
• What happens when the ribosome reaches a stop codon during translation?

  The ribosome detaches and translation stops
• Why is the genetic code described as degenerate?


  Because most amino acids are coded for by more than one triplet of bases
• How many different amino acids does the genetic code need to code for?

  20
• What is the mathematical formula used to prove the degeneracy of the genetic code?

  4 to the power of n
• How many combinations of codes are possible with three bases from four DNA bases?

  64
• What is a silent mutation?


  A mutation that does not affect the final protein
• What does the term universal mean in the context of the genetic code?

  The same triplet of bases codes for the same amino acid in almost every living organism
• Why is the universality of the genetic code important for gene technologies?

  It allows for genetic engineering between different species
• What does non-overlapping mean in the context of the genetic code?

  Each base in a gene is part of only one triplet of bases
• What is the advantage of a non-overlapping genetic code?

  It minimizes the impact of mutations on the polypeptide chain
• What are introns?


  Sections of DNA that do not code for amino acids
• What percentage of DNA is made up of introns?

  Over 90 percent
• What are exons?


  Sequences of bases that do code for amino acids
• What is the difference between the genome and the proteome?

  • Genome: Complete set of DNA within one cell, all genes of the organism
  • Proteome: Full range of proteins in one cell
• How does the genome of different organisms vary?


  Different species have very different genomes
• How many DNA base pairs are in the human genome?

  About three billion
• How many DNA base pairs do bacteria typically have in their genome?

  About six hundred thousand
• What is gene regulation?


  The process of turning genes on and off
• Why do specialized cells produce different proteins?

  Because they respond by producing the proteins they currently need
• What happens to introns during mRNA processing?

  They are spliced out before the final mRNA is formed
• What is the significance of alternative splicing?

  It allows for different proteins to be produced from the same gene
• What is the role of the ribosome during translation?


  It moves along the mRNA to synthesize proteins
• What is the function of a genetic code wheel?

  To determine which triplet codes for which amino acid
• How do mutations affect protein synthesis?

  They can change the amino acid sequence of the protein
• What is the importance of the genetic code in biotechnology?

  It allows for the manipulation of genes across different species