5.4 explain how mutations bring about genetic variation
Mutations cause a change in the characteristic of an individual and can be inherited.
Sickle cell anaemia - there is a substiution for glutamate for valine. so this causes variation from the normal glutamate.
This can be passed down to offspring so this is genetic variation.
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Down syndrom is an example of aneuploidy. It is caused from having an extra chromosome because of the failure to separate in meiosis I anaphase. This is variation because there is an extra chromosome and this can be passed on to offspring so this is genetic variation. The extra chromosome is usually due to non - disjunction of chromosome 21 in the egg (trisomy)
In a few cases the extra chromosome is from the sperm
Children with down syndrome have learning disabilities, a round flat face, eyelids that appear slant upwards and they are at risk for infections and heart defect
