4. Genetic Information Variation And Relationships - Investigating Diversity Flashcards
(7 cards)
How was genetic diversity traditionally measured?
By observing the characteristics of an organism.
What are there limitations with using observable characteristics?
Because a large number of them are coded for by more than one gene. They are polygenic. This means they are not discrete from one another but rather vary continuously. It is often difficult to distinguish one from another. Characteristics can also be modified by the environment, therefore differences may be a result of different environmental conditions rather than different alleles.
For example height in humans is determined by a number of genes, but environmental factors like diet can influence this.
What has inferring DNA differences from observable characteristics been replaced by?
Directly observing DNA sequences themselves.
What 3 ways can we now compare genetic diversity?
- Comparison of DNA base sequences
- Comparison of mRNA base sequences
- Comparison of amino acid sequences in proteins
How can data from DNA now be produced thanks to the advent of gene technology?
In these computerised systems, each nucleotide base can be tagged with a different coloured fluorescent dye - adenine (green), thymine (red), cytosine (blue) and guanine (yellow). This produces a series of coloured bands, each of which represents one of the four nucleotide bases.
How can we measure genetic diversity of a species by comparing DNA base sequences?
We can sample the DNA of its members and sequence it to produce a pattern of coloured bands. Analysis of these patterns allows us to compare one species with another or one individual with another of the same species to determine how diverse they are. Patterns are scanned by lasers and interpreted by computer software to give the DNA nucleotide base sequence in a fraction of time.
What else can we use these techniques to determine?
The evolutionary relationships between species.
