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Following a mutagenesis experiment to identify novel genes affecting the circadian clock in Drosophila melanogaster you discover several mutants. You start considering two of those mutants that you call c and d. The two homozygous c/c and d/d are arrhythmic (arrhythmic is the definition of their phenotype), whereas the two heterozygous C/c and D/d are rhythmic (rhythmic is the definition of their phenotype) with a 24h period. You make two true-breeding stocks: stock 3 homozygous for c and stock 4 homozygous for d. You cross them in both directions and in both cases you observe complementation with no difference between males and females. Then you take the progeny of one cross, for instance the F1 of Females 3 x Males 4, and you perform a Testcross. Out of 1000 flies resulting from the Testcross only 125 are rhythmic.

What is the genotype of Females 3 ?

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Related questions

In Drosophila, the autosomal recessive brown eye color mutation (b) displays interactions with both the X-linked recessive vermilion mutation (v) and the autosomal recessive scarlet (s) mutation. Flies homozygous for brown and simultaneously hemizygous or homozygous for vermilion have white eyes. Flies simultaneously homozygous for both the brown and scarlet mutations also have white eyes. Flies that are wildtype at all 3 loci have wildtype eye color. Flies that are homozygous or hemizygous for the recessive mutant at only one locus show that mutations color. (i.e. brown, vermillion or scarlet).
Use this information to answer the next 4 questions.

Predict the F1 progeny of a cross between a true breeding scarlet female X brown male.

a) females wild type
males scarlet
b) females scarlet
males wildtype
c) all white
d) all wildtype

According to the multiplication rule of probability, the chance of crossing two pea plants that are heterozygous for height and have none of four offspring showing the recessive short phenotype is:A. ¼ × ¼ × ¼ × ¼.

B. ¾ × ¾ × ¾ × ¾.

C. (¼ × ¼ × ¼ × ¼) + (¾ × ¾ × ¾ × ¾).

D. ¼ + ¼ + ¼ + ¼.

E. None of the above.

What characteristic is exhibited by an X-linked trait?

a) Only females have the trait.
b) Females inherit X-linked traits from their maternal parent only.
c) Females can inherit a gene for an X-linked trait from either parent.

d) Males inherit X-linked traits from their paternal parent only.

e) Males can inherit a gene for an X-linked trait from either parent but normally inherit it from their fathers.
What characteristic is exhibited by a Y-linked trait?
a) Y-linked traits appear only in male offspring of men with the trait.
b)Y-linked traits are only passed from father to son.
c) Y-linked traits can be passed from mother to son.
d) Both A and B are characteristics of Y-linked traits.
e) Both A and C are characteristics of Y-linked traits.
Which of the following codes for a phenotypic human male?
a) XO with a copy of SRY gene on an autosomal chromosome?
b) XXYY with one copy of the SRY gene deleted?
c) XX with a copy of SRY gene on an autosomal chromosome?
d) All of the above sex compliments results in a person with a sex phenotype of male.
e) XY with the SRY gene located on an autosomal chromosome?
In Drosophila, yellow body is due to an X-linked gene (Xy) that is recessive to the gene for gray body (X+). A homozygous gray female is crossed with a yellow male. What are the genotypes of the F1 progeny?
In some goats, the presence of horns is produced by an autosomal gene that is dominant in males and recessive in females. A horned female is crossed with a hornless male. The F1 offspring are intercrossed to produce the F2. What proportion of the F2 females will have horns?
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b)3/4
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None
a) Females are X+X+; males are X+Y.
b)Females are X+X+; males are XyXy.
c)Females are X+X+; males are XyY.
d) Females are X+Xy; males are XyY.
e) Females are X+Xy; males are X+Y.

Females inherit X-linked traits from their maternal parent only.
Females can inherit a gene for an X-linked trait from either parent.
Males inherit X-linked traits from their paternal parent only.
Males can inherit a gene for an X-linked trait from either parent but normally inherit it from their fathers.
Males can inherit a gene for an X-linked trait from either parent but normally inherit it from their fathers.

Answer the following Linked to sex genetics problems:

1.) In Drosophila the recessive mutation linked to the X chromosome, scalloped ( sd ), causes the edge of the wings to be irregular. Present the results (you must prepare the crossing scheme) phenotypic for F1 and F2 for a cross between:

A) female scallop and a normal male (regular edges)

B) A normal (homozygous) female and a scallop male .

C) Compare these results with those that would be obtained if scallop were an autosomal recessive mutation.

2.) In Drosophila the autosomal recessive ebony mutation (e) is located on chromosome 3 and produces a dark body in the fly that expresses it. What will be the phenotypic proportions for F1 and F2 that will be obtained from a cross between a scallop female and homozygous for a normal body, with an ebony male with normal wings? Solve by the bifurcated lines method.

3.) In Drosophila the recessive mutation linked to the vermilion X chromosome (v) produces bright red colored eyes in contrast to the wild phenotype that has brick red eyes. An autosomal recessive mutation, suppressor vermilion (su-v) causes homozygous or hemizygous males to females present vermilion red brick eyes. In the absence of the vermilion allele su-v has no effect on the phenotype of the eye. Determine the genotype and phenotype of F1 and F2 at a cross between a homozygous female for vermilion and su-v, with a vermilion male and wild homozygous for su-v (su-v + su-v + ) . Present the diagram of bifurcated lines for these crosses.

4.) At a crossroads with Drosophila involving recessive mutations white (linked to the X chromosome) and sepia (autosomal recessive) that produces dark eyes, predict the results of F1 and F2 when crossing pure parents with the following phenotypes.

A.) White females with sepia males.

B.) Sepia females with white males

5.) Two mothers have given birth to their children at the same time in an urban hospital with an excess of patients. The child of couple 1 has hemophilia, a condition caused by a recessive allele linked to the X chromosome. Neither parent has the condition. Couple 2 has a normal child even though the father is a hemophiliac. Several years later, couple 1 filed a lawsuit alleging that the babies were changed after birth and you are called to testify as a genetic counselor. What information would you give the jury in relation to the allegation of the couple 1?

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