A researcher is attempting to determine the inheritance pattern exhibited by the

Question

A researcher is attempting to determine the inheritance pattern exhibited by the alleles determining shell color in a species of freshwater snail. The trait is known to be controlled by alleles at a single autosomonal locus, and the researcher hypothesizes that there are two alleles, one for brown which is completely dominant to the allele for yellow. A mating between a brown-shelled snail and a yellow-shelled snail, both from pure-breeding lines, produces progeny that are brown shelled. The mating of two F1 snails produces an F2 consisting of 54% with yellow shells and 46% with brown shells. The researcher wishes to carry out a X^2 test on F2 outcome and deicides to compare his observed values of 54% and 46% with a ratio of 1:1 which is close to the observed results> The resultant X2 value is small and, because of that, the researcher records in his notebook that "the deviation is definetly due to chanec" and that "the hypothesis must be correct" -THE RESEARCHER HAS MADE A NUMBER OF ERRORS -

WHAT ADDITIONAL INFORMATION WOULD BE REQUIRED TO CARRY OUT AN ACCURATE X^2 TEST ON THESE DATA?

Explanation / Answer

The depiction of a method of inheritance comprises of three primary classes:

1. Number of involved loci

Ø Monogenetic – one locus

Ø Oligogenetic – few loci

Ø Polygenetic – many loci

2. Involved chromosomes

Ø Autosomal – loci are not situated on a sex chromosome

Ø Gonosomal – loci are situated on a sex chromosome

Ø X-chromosomal – loci are situated on the X-chromosome (the more common case)

Ø Y-chromosomal – loci are situated on the Y-chromosome

Ø Mitochondrial – loci are situated on the mitochondrial DNA

3. Correlation genotype–phenotype

Ø Dominant

Ø Intermediate

Ø Recessive

Ø Over dominant

Ø Under dominant

These three classes are a piece of each accurate portrayal of a method of inheritance in the above request. Likewise, more determinations may be included as takes after:

4. Coincidental and environmental interactions

Ø Penetrance

Ø Complete

Ø Incomplete

Ø Expressivity

Ø Invariable

Ø Variable

Ø Heritability

Ø Maternal or paternal imprinting phenomena

5. Sex-linked interactions

Ø Sex-linked inheritance

Ø Sex-limited phenotype expression

Ø Inheritance through the maternal line

Ø Inheritance through the paternal line

6. Locus–locus interactions

Ø Epistasis with other loci

Ø Gene coupling with other loci

Ø Homozygotous lethal factors

Ø Semi-lethal factors

Determination and depiction of a method of inheritance is accomplished essentially through inheritance of family information. On the off chance that the included loci are known, method of molecular can likewise be needed.

In that specific case data with respect to molecular genetics will assume imperative part to acquire precise result.

Techniques in molecular genetics as follows

Polymerase chain reaction

Cloning DNA in bacteria

Cell cultures

DNA isolation

mRNA isolation

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