BIOL 2040 Lecture Notes - Lecture 10: Miscarriage, Advanced Maternal Age, Intellectual Disability

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Published on 1 Feb 2013
BIOL 2040
Lecture 10
Human Genetics
Consequences of mutations
Gain of function
o Increases activity of the protein encoded by the mutated gene
o Overexpression of the protein
o Inappropriate expression (wrong place, wrong time)
Loss of function
o Decreases activity of the protein encoded by the mutated gene
o Not enough protein production
Genetic Mutations
Somatic mutations
o Mutations are of the cells other than gametes (is not inheritable)
o Will not be passed on
85% of cancer is this type
o Mutations often kill the cells
o Make the cell cancerous
o When the cell dies, so does the mutation
Germline Mutations
o They will be found in every cell descended from the zygote to which that mutant gene
o Included with these mutated genes is the passing on of these genes
Why do Meiotic errors occur?
They appear to be accidental but the age of the mother seems to have an effect on the
magnitude of errors
How do Mistakes Occur?
The spindle fibre must try and find the centromeres perfectly
What are the odds of such an error?
o Sometimes there can be too many chromosomes taken into one gametic cell (3:1 ratio
of chromosomes instead of 2:2)
“Abnormal chromosome #”
Called nondisjunction
Pairs of homologous chromosomes don’t separate normally during
meiosis (contain 2 or no copies of a certain chromosome set)
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