1.5 + 1.6 Structure of the genome AND Mutations

• Define the term 'genome'.

  An organism's entire hereditary information encoded in DNA.
• What is a genome made up of?

  Genes- DNA sequences that code for proteins

  Non coding sequences
• Give three functions of non-coding regions of DNA.

  Regulating transcription

  Being transcribed to form tRNA

  Being transcribed to form rRNA
• What are Mutations?


  Changes in the DNA sequence that can result in no protein or an altered protein being synthesised.
• What do single gene mutations involve?

  Alteration of a DNA nucleotide sequence.
• Name the three types of single gene mutations.

  Substitution

  Insertion

  Deletion
• Describe a substitution mutation.


  One nucleotide is swapped for another nucleotide.
• What are the three outcomes of a substitution mutation?


  Missense, nonsense, splice-site
• Describe a missense mutation and the impact it has on the protein produced.


  One amino acid being changed for another. This may result in a non-functional protein or have little effect on the protein.
• Describe a nonsense mutation and the impact it has on the protein produced.

  A premature stop codon is produced which results in a shorter protein.
• Describe a splice-site mutation and the impact it has on the protein produced.

  Some introns are retained and/or some Exons are not included in the mature transcript.
• What occurs when a single gene deletion mutation occurs?

  This involves a DNA nucleotide being removed from the DNA sequence. This results in a frameshift mutation.
• Describe a single gene insertion mutation.

  An extra DNA nucleotide is added into the DNA sequence. This results in a frameshift mutation.
• what is a frameshift mutation and why does it have a major affect on the structure of the protein produced?

  Frameshift mutation: insertion or deletion of nucleotides, shifts the reading frame of the genetic code (all of the DNA codons after the point of mutation are changed), leading to a completely different amino acid sequence.
• Name the four possible chromosome structure mutations.

  Deletion

  Inversion

  Duplication

  Translocation
• Describe a chromosome deletion mutation.


  A section of a chromosome is removed.
• Describe a chromosome Inversion mutation.

  A section of a chromosome is reversed.
• Describe a chromosome duplication mutation.


  A section of a chromosome is added to its homologous partner.
• Describe a chromosome translocation mutation.


  A section of a chromosome is added to a non-homologous partner chromosome.
• Which type of chromosome mutation is important in evolution and explain the reason for this.

  Duplication mutations.

  Duplication allows potential beneficial mutations to occur in a duplicated gene whilst the original gene can still be expressed to produce it's protein.