Genetics Answers

Consider how DNA transcription is controlled. How could a PNA be used to serve a similar function?

(a)  Mendel did not know of the existence of chromosomes. Had he known, what change might he have made in his Principle of Independent Assortment?

(b)  Consider 4 different genes represented by a, b, c, d.  If a is linked to b, and b to c, and c to d, does it follow that a recombination experiment would detect linkage between a and d? Explain.

A phenotypically wild-type female fruit fly that was heterozygous for genes controlling body color and wing length was crossed to a homozygous mutant male with black body (allele b) and vestigial wings (allele vg). The cross produced the following progeny: gray body, normal wings 126; gray body, vestigial wings 24; black body, normal wings 26; black body, vestigial wings 124. Do these data indicate linkage between the genes for body color and wing length? What is the frequency of recombination?

Deduce and explain the effects of mutations:

a) in the operator, so that the repressor is no longer able to bind.

b) in lacI, so that the repressor is no longer synthesized.

c) in the promoter, so that RNA polymerase no longer binds.

d) in lacI, so that the repressor no longer binds to lactose.

e) in lacY that causes transcription to terminate in the middle of the gene.

f) location unknown, which prevents the lac mRNA from being degraded. 

Why can't normal hydrogen bonding with nitrogenous bases of DNA occur when the molecule is in duplex/helix form?

The ability to taste a bitter chemical, phenylthiocarbamide (PTC), is

due to a dominant gene. Use T and t to symbolize the two alleles of this gene.

A lawyer sets out to prove that a child with type A blood is the son of a man with type B blood and a mother with type AB blood. Determine if it is possible for the man to be the father. Is he definitely the father?

a. Test cross method

b. Genotypic Ratio

c. Phenotypic ratio

A) A cross was made between pure breeding plants differing in two  

characters (colour and shape of seed) and the progenies were inter-crossed  

to produce F2 population. Four types of phenotypes; yellow round (1108),  

yellow wrinkled (382), green round (366) and green wrinkled (140) were  

observed in F2. Use the chi-square test to determine if these results are  

due to independent assortment.

B) Explain prophase and metaphase stages of mitosis