Two short paper about biology - Essay Example

If a point mutation changes the fifteenth base from a “U” to an “A”, the resulting sequence is as follows: AUG: start codon Met/M , ACU: Thr/T, CAU: His/H, CGC : arginine Arg/R ,UGA: stop codon (opal), AGU: Ser/S, UUA: Phe/F, and, CGA: Arg/R. If ‘C’ is inserted between the fourth and fifth bases, the resulting sequence (AUG ACC UCA UCG CUG UAG UUU ACG A), will be: (Met/M, Thr/T, Ser/S, Ser/S, Leucine (Leu/L), Stop (amber), Phe /F, and Thr/T, respectively. The base “A” stands alone and has no significance in this case.

The insertion of two bases in a row would be more devastating. This is because it will alter the entire sequence by changing the codons, whereas, inserting three bases does not interfere with other codons(Wang, Parrish and Wang). Carriers of a genetic disease usually have one copy of gene mutation and are protected from showing symptoms of the disease, by the presence of a normal gene copy (Feero, Zazove and Stevens). Based on knowledge on possible patterns of inheritance for genetic disorders, it is possible to calculate the worst possible risk of two people conceiving a child with a genetic disorder, based on their belonging to the Finnish population ( 1 % are carriers of myoclonus epilepsy, MIM 607876).

If the gene mutation for MIM 607876 is on a sex chromosome; an X-linked recessive condition requires two people to be carriers of the gene mutation, in order to conceive an affected child. If the two people are carriers of the gene mutation, there is a 50 % chance of conceiving a child with the disease (50/100 *1/100=0.005). X-linked dominant conditions only occur where individuals have the disease and they require only one genetic mutation to conceive an affected child (Feero, Zazove and Stevens).

If the gene mutation for MIM 607876 is on an autosome, two patterns of inheritance are possible. Autosomal dominance