1. You have isolated 9 different mouse mutants that have developmental phenotypes associated with limb development (malformed limbs). To determine how many different genes are repsented in your 9 mutants, you generate true-breeding lines of each mutant. For all 9 mutants, when crossing a true-breeding mutant to true-breeding wildtype, the F1 are wildtype. Below is a complementation table summarizing the data of all the complementation test, where + = wiltype progeny and - = mutant progeny with malformed limbs. Mutants 1 1 2 3 4 5 6 7 8 9 + + - + + + + 2 + 1 + + + + + 1A. For mutant 2 and mutant 4: 3 + + + + + + + 4 I + + - + + + + 5 - + + + + + + 6 + + + + + + + + Do these two mutants complement or fail to complement? Are these mutant alleles of the same gene or different genes? 7 + - + + + + + 1B. How many different genes are represented across the 9 mutants? 8 + - + + + + - + 9 + + - + + + + +

1. You have isolated 9 different mouse mutants that have developmental phenotypes associated with limb development (malformed limbs). To determine how many different genes are repsented in your 9 mutants, you generate true-breeding lines of each mutant. For all 9 mutants, when crossing a true-breeding mutant to true-breeding wildtype, the F1 are wildtype. Below is a complementation table summarizing the data of all the complementation test, where + = wiltype progeny and - = mutant progeny with malformed limbs. Mutants 1 1 2 3 4 5 6 7 8 9 + + - + + + + 2 + 1 + + + + + 1A. For mutant 2 and mutant 4: 3 + + + + + + + 4 I + + - + + + + 5 - + + + + + + 6 + + + + + + + + Do these two mutants complement or fail to complement? Are these mutant alleles of the same gene or different genes? 7 + - + + + + + 1B. How many different genes are represented across the 9 mutants? 8 + - + + + + - + 9 + + - + + + + +

Biology: The Dynamic Science (MindTap Course List)

4th Edition

ISBN:9781305389892

Author:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Publisher:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Chapter13: Genes, Chromosomes, And Human Genetics

Section: Chapter Questions

Problem 8TYK: Another gene in Drosophila determines wing length. The dominant wild-type allele of this gene...

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1. There are two different variations at STR locus THO1. Where did these variations come from? b) The STR locus D21S11 only has one variation. Why?
2. Uniparental disomy is a rare phenomenon in whichonly one of the parents of a child with a recessivedisorder is a carrier for that trait; the other parent ishomozygous normal. By analyzing DNA polymorphisms, it is clear that the child received both mutantalleles from the carrier parent but did not receive anycopy of the gene from the other parent.a. Diagram at least two ways in which uniparentaldisomy could arise. (Hint: These mechanismsall require more than one error in cell division,explaining why uniparental disomy is so rare.)Is there any way to distinguish between thesemechanisms to explain any particular case ofuniparental disomy?
2. Uniparental disomy is a rare phenomenon in whichonly one of the parents of a child with a recessivedisorder is a carrier for that trait; the other parent ishomozygous normal. By analyzing DNA polymorphisms, it is clear that the child received both mutantalleles from the carrier parent but did not receive anycopy of the gene from the other parent.a. Diagram at least two ways in which uniparentaldisomy could arise. (Hint: These mechanismsall require more than one error in cell division,explaining why uniparental disomy is so rare.)Is there any way to distinguish between thesemechanisms to explain any particular case ofuniparental disomy?b. How might the phenomenon of uniparental disomyexplain rare cases in which girls are affected withrare X-linked recessive disorders but have unaffectedfathers, or other cases in which an X-linked recessive disorder is transmitted from father to son?c. If you were a human geneticist and believed oneof your patients had a disease syndrome caused…
Consider two maize plants:a. Genotype C/cm ; Ac/Ac+, where cm is an unstableallele caused by a Ds insertionb. Genotype C/cm, where cm is an unstable allele causedby Ac insertionWhat phenotypes would be produced and in whatproportions when (1) each plant is crossed with a basepair-substitution mutant c/c and (2) the plant in part a iscrossed with the plant in part b? Assume that Ac and care unlinked, that the chromosome-breakage frequencyis negligible, and that mutant c /C is Ac+.
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5. A strain of Neurospora with genotype A B is crossed with a strain with the genotype a b. Half the progeny are A B and half are a b. Explain how this is possible?
8. In guinea pigs, the allele for black fur (B) is dominant over the allele for white fur (b). Similarly, the allele for straight hair (H) is dominant over the allele for having rough hair (h). Pure breeding rough haired guinea pigs with black fur were crossed with pure breeding straight haired guinea pigs with white fur. a. State the genotype and the phenotype of the F1 individuals produced as a result of this cross.b. Two F1 offspring were mated together. Calculate the expected ratio of phenotypes in the F2 generation.c. Show the completed Punnett square below.
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1. a. Assume that two transcription factors are required for expression of the blue pigmentationgenes in pansies. (Without the pigment, theflowers are white.) What phenotypic ratioswould you expect from crossing strains heterozygous for wild-type and recessive amorphicalleles for each of the genes encoding thesetranscription factors?b. Now assume that either transcription factor issufficient to get blue color. What phenotypicratios would you expect from crossing the sametwo heterozygous strains?
The wild-type (normal) fruit fly, Drosophila melanogaster, has straight wings and long bristles. Mutant strains have been isolated that have either curled wings or short bristles. The genes representing these two mutant traits are located on separate chromosomes. Carefully examine the data from the following five crosses shown below (running across both columns). (a) Identify each mutation as either dominant or recessive. In each case, indicate which crosses support your answer. (b) Assign gene symbols and, for each cross, determine the genotypes of the parents.
A. Look at the pedigree, and DISREGARD individual II-8 for the moment. Is the pattern of inheritance of Unetan syndrome dominant or recessive? You may assume that the gene is FULLY-PENETRANT in this family. Please give two specific reasons that support your conclusion. B. Now, looking at BOTH the pedigree AND at the Southern blot, is this trait autosomal, X-linked, or Y-linked? Please give two specific reasons that support your conclusion. Once again, disregard II-8 for the moment. One of your two reasons must refer specifically to evidence present in the Southern blot. C. Define the gene alleles associated with Unetan syndrome. Your alleles MUST be consistent with the pattern of inheritance, AND your genetic notation must be consistent with that used throughout the course. Unetan syndrome allele: ________ Normal allele: ________
2. Null mutations are valuable genetic resources becausethey allow a researcher to determine what happens to anorganism in the complete absence of a particular protein. However, it is often not a trivial matter to determinewhether a mutation represents the null state of the gene.a. Geneticists sometimes use the following test forthe nullness of an allele in a diploid organism: If theabnormal phenotype seen in a homozygote for theallele is identical to that seen in a heterozygote(where one chromosome carries the allele in question and the homologous chromosome is known tobe completely deleted for the gene) then the alleleis null. What is the underlying rationale for thistest? What limitations might there be in interpreting such a result?