Question

Please answer these 2 questions completely with your own words. Thank you for your help.

7. A man has a widow’s peak, he is heterozygous for this trait. His wife has a straight hairline she is homozygous recessive for the trait. How is an understanding of Mendel’s Law of Segregation relevant to drawing a Punnet Square? Draw a Punnett square to solve the problem. What do the letters on the outside of the box represent? What do the letters in the squares represent? What do the resulting numbers mean?

8. If a gene has the following base sequence- ATAGCCAAG, (a) describe how and where it would be transcribed, (b) using the transcribed sequence of bases, describe where the sequence would be translated, and provide the resulting sequence of amino acids.

Answer 1

7. As per the segregation law, just a one of the two genes present in an organism disseminated to every gamete (egg or sperm cell) it produces, and the gene copies are apportioned randomly.

Here we have seen this:

Aa (Man)                   X                           aa (wife)………………….Parent

Genotypes of F1 generation are shown in Punnet square:

	A	a
a	Aa	aa
a	Aa	aa

The four-squared box shown the above for the F1 generation is known as a Punnett square. To prepare a Punnett square, the top grid represents the gametes of father and side grid represents the gametes of mother.

The inside four genotypes are for F1 offspring. Genotypic ratio is 1:1. Phenotypic ratio is also 1:1 (Widow’s peak : Straight hair line)

8. Base sequence- ATAGCCAAG

(a) In nucleus this short portion DNA transcribed into RNA with the help of RNA polymerase.

After transcription the base sequence are: UAUCGGUUC

(b) After transcription translation will occur within ribosome.

The resulting sequence of amino acids is:

UAU—CGG—UUC (mRNA sequence)

Tyr—Arg--Phe (amino acid sequence)