Investigating diverity

Cards (4)

  • How can genetic diversity within or between species be measured?
    ● Comparing frequency of measurable or observable characteristics
    ● Comparing base sequence of DNA
    ● Comparing base sequence of mRNA
    ● Comparing amino acid sequence of a specific protein encoded by DNA and mRNA
  • Explain how comparing DNA, mRNA and amino acid sequences can indicate relationships between organisms within a species and between species
    ● More differences in sequences → more distantly related / earlier common ancestor
    ● As mutations (change in DNA base sequences) build up over time
    ● More mutations cause more changes in amino acid sequences
  • Explain the change in methods of investigating genetic diversity over time
    ● Early estimates made by inferring DNA differences from measurable or observable characteristics
    ○ Many coded for by more than one gene → difficult to distinguish one from another
    ○ Many influenced by environment → differences due to environment not genes
    Gene technologies allowed this to be replaced by direct investigation of DNA sequences
  • Explain considerations in quantitative investigations of variation within a species
    ● Collect data from random samples→ removes bias
    ● Use large sample sizerepresentative of whole population
    Ethical sampling→ must not harm organism
    ● Calculate a mean value of collected data + S.D of mean
    Interpret mean values + their standard deviations
    ○ S.D shows spread of values about mean → ↑ S.D = ↑ variation
    ○ S.D overlap, causing values of 2 sets of data to be shared, any difference due to chance / not signif
    ● Use statistical test → analyse whether there is a sig diff between pops