9.1 - Gene mutation

• What‘s the definition of a gene mutation ?

  A change in the base sequence of chromosomes
• When can gene mutations arise spontaneously ?

  DNA replication
• 2 common gene mutations ?

  Base deletion and base substitution
• Why do not all base substitutions result in a change in the AA sequence ?

  The degenerate nature of the genetic code
• What’s a base substitution ?

  A nucleotide in a DNA molecule is replaced by another that has a different organic base
• What effect can a base mutation have on the tertiary structure of a protein ?

  AA sequence altered, forms different bonds, altering proteins shape so may not function properly
• What’s a base deletion ?

  When a nucleotide is lost from the DNA sequence
• What can increase the rate of gene mutation ?

  Mutagenic agents
• What are chromosome mutations ?

  Changes in the structure or number of whole chromosomes
• What are the 2 forms of chromosome mutations ?

  Changes in the whole set or changes in the number of individual chromosomes
• When do changes in the whole set of chromosomes occur ?

  Organisms have 3 or more sets rather than 2
• What’s the condition called when an organism has more than 2 sets of Chromosmes ?

  Polyploidy
• When can the number of individual chromosomes change ?

  Meiosis
• What’s it known as when individual homologous pairs of chromosomes fail to separate during meiosis ?

  Non-disjunction
• What’s an example of non-disjunction in humans ?

  Down syndrome