investigating diversity Flashcards
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 the key considerations in quantitative investigations of variation
within a species
● Collect data from random samples (use a random number generator) → removes bias
● Use large sample size (or sample until stable running mean) → representative of whole population
● Ethical sampling (where applicable) → must not harm organism / allow release unchanged
● Calculate a mean value of collected data and standard deviation of that mean
● Interpret mean values and their standard deviations (S.D)
○ S.D shows spread of values about the mean → higher S.D = higher variation
○ If standard deviations overlap, causing values of two sets of data to be shared, any difference
between the two may be due to chance / not significant
● Use [named] statistical test → analyse whether there is a significant difference between populations
