Biodiversity and Gene Technology (A-level Biology)

Biodiversity and Gene Technology

Overview

Overall, gene technology has led to a change in the methods of investigating genetic diversity. We used to look mainly at measurable or observable characteristics, but now we can investigate DNA sequences directly, and can also look at mRNA and amino acid sequences.

Genetic Polymorphism

• We can measure genetic biodiversity. Through looking at genetic polymorphisms, we can measure genetic biodiversity. Polymorphisms are when there are two (or more) alleles at the locus of a chromosome.
• Polymorphisms introduce variation. Different alleles can be present at the locus of a chromosome. This means that when polymorphisms arise, they are all slightly different to one another. This introduces an aspect of variation.
• The number of polymorphisms can determine genetic variability. If we can work out the proportion of genetic polymorphisms in an organism, we can work out genetic variability through the following formula: 

Variation

When studying biological diversity (either species diversity or genetic diversity) we are measuring variation.

Variation is the level of differences between individuals. No two individuals are the same, even identical twins (due to environmental factors). Variation can be in physical appearance, genetics, biochemistry and other factors.

Interspecific and Intraspecific Variation

Interspecific variation is variation between individuals of the same species.

Intraspecific variation is variation between different species.

Continuous and Discontinuous Variation

Continuous variation involves features that have intermediate values along a range. There are no distinct categories. For example, height can vary and be any value in a range.

Continuous variation can be plotted on a distribution such as a normal distribution plot (i.e. bell curve).

Discontinuous variation involves features that have distinct categories, with no individuals in between. For example, eye colour only has a few variants: black, brown, green, blue.

Discontinuous variation must be plotted using bar graphs (because there is no range of distribution).