Question 1

One map unit on a human chromosome corresponds roughly to

Accepted Answer

A)   10 base pairs.
B)   1 million base pairs.
C)   1 base pair.
D)   100,000 base pairs.
E)   1,000 base pairs.F) A) and E)
G) A) and C)

Question 2

What process observed by Curt Stern resulted in twin spot formation in Drosophila?

Accepted Answer

A)   Chromosome loss
B)   Mitotic recombination
C)   Chromosome nondisjunction
D)   Meiotic recombination
E)   Incomplete dominanceF) A) and C)
G) A) and B)

Question 3

Neurospora crassa, a mycelial-form fungus, is useful for genetic and biochemical studies because it

Accepted Answer

A)   produces meiotic products contained in an ascus.
B)   is haploid.
C)   has a relatively short life cycle.
D)   All of the above
E)   None of the aboveF) C) and D)
G) B) and E)

Question 4

A polymorphic DNA marker is one in which more than one type of sequence is found in the population at that site in the genome.

Accepted Answer

A) True 
 B)False

Question 5

What are heterokaryons?

Accepted Answer

They are fungal cells in which...

Question 6

Mitotic rather than meiotic recombination analysis has been used to construct genetic maps in the fungus Aspergillus.

Accepted Answer

A) True 
 B)False

Question 7

If two genes are linked, then the frequency of parental ditype tetrads resulting from a two-point testcross will be

Accepted Answer

A)   equal to the frequency of nonparental ditype tetrads.
B)   equal to the frequency of the tetratype tetrads.
C)   greater than the frequency of the nonparental ditype tetrads.
D)   less than the frequency of tetratype tetrads.
E)   none of the above.F) A) and B)
G) B) and D)

Question 8

If 156 tetrads are analyzed following a series of two-point testcrosses in Neurospora, and 102 of them are PD, 40 are T, and the remaining 14 are NPD, what is the frequency of recombination between the two genes?

Accepted Answer

The recombination frequency is...

Question 9

In the life cycles of yeast and Chlamydomonas, the haploid vegetative cells never undergo fusion to form a diploid cell.

Accepted Answer

A) True 
 B)False

Question 10

How can you calculate the recombination frequency between a and b in the previous question?

Accepted Answer

We can assume that the grandmother is homozygous wild-type for the genes, since the recessive alleles are rare. Her daughter will then be a heterozygote (a+ b+/a b). When she marries a normal a+ b+/Y man, their male children will express all four possible phenotypic classes (since they are hemizygous): the female parental a+ b+ and ab and the recombinants a+ b and a b+. If a large number of such pedigrees are available, the recombination frequency can be calculated.

Question 11

In the yeast Saccharomyces cerevisiae, when an MATa mating type fuses with a MATα mating type, the resulting cell is diploid.

Accepted Answer

A) True 
 B)False

Question 12

In order to use tetrad analysis in an organism to map the distance between a gene and the centromere on a chromosome,

Accepted Answer

A)   the organism may produce either ordered or unordered tetrads.
B)   the organism must produce unordered tetrads.
C)   the parental centromeres must be distinguishable.
D)   the chromosome must have a cytological marker.
E)   the organism must produce ordered tetrads.F) C) and D)
G) A) and E)

Question 13

During the analysis of an ordered tetrad, 22 percent of the asci showed second-division segregation for a particular genetic locus. What is the distance between the gene and the centromere?

Accepted Answer

Eleven map...

Question 14

DNA markers allow genetic mapping in humans on the basis of molecular phenotypes, rather than outwardly visible phenotypes.

Accepted Answer

A) True 
 B)False

Question 15

At what stage may mitotic recombination occur?

Accepted Answer

When homologs align ...

Question 16

Explain how the two formulas for determining the distance between linked genes in diploid organisms and in tetrad analysis relate to each other.

Accepted Answer

In diploid organisms, we calculate the recombination frequency by determining the percentage of recombinant progeny out of the total number of progeny. In tetrad analysis, we determine the proportion of recombinant spores in tetrads produced from crosses out of the total number of spores. Therefore, in diploid organisms, the formula is: (number of recombinants/total number of progeny) × 100. In tetrad analysis, it is: (1/2T + NPD/total tetrads) × 100.

Question 17

Following a series of two-point testcrosses in Neurospora, 200 tetrads were analyzed. Of these, 100 were PD and 100 were NPD. These two genes are

Accepted Answer

A)   50 map units apart on the same chromosome.
B)   100 map units apart on the same chromosome.
C)   epistatic.
D)   on different chromosomes.
E)   adjacent to each other on the same chromosome.F) A) and B)
G) A) and C)

Question 18

X-linked genes in humans are easier to study than autosomal genes because

Accepted Answer

A)   recombination frequencies are lower.
B)   hemizygosity in males allows the effects of genotypic pairings to be observed.
C)   Suitable pedigrees are easily available.
D)   they do not have as high a recombination rate.
E)   there are fewer genes to deal with.F) All of the above
G) B) and E)

Question 19

How does the arrangement of ascospores in the tetrads of yeast differ from that in Neurospora crassa?

Accepted Answer

The ascospores in a tetrad of yeast are unordered (random), whereas those of Neurospora are linearly ordered.

Question 20

Describe the possible tetrad types resulting from a cross qr × q+r+ in which the genes are located on separate chromosomes.

Accepted Answer

Depending on the metaphase alignment of ...

Exam 7: Chromosomal Basis of Inheritance

One map unit on a human chromosome corresponds roughly to

Correct Answer
verified

What process observed by Curt Stern resulted in twin spot formation in Drosophila?

Correct Answer
verified

Neurospora crassa, a mycelial-form fungus, is useful for genetic and biochemical studies because it

Correct Answer
verified

A polymorphic DNA marker is one in which more than one type of sequence is found in the population at that site in the genome.

Correct Answer
verified

What are heterokaryons?

Correct Answer
verified
They are fungal cells in which...
View Answer

Mitotic rather than meiotic recombination analysis has been used to construct genetic maps in the fungus Aspergillus.

Correct Answer
verified

If two genes are linked, then the frequency of parental ditype tetrads resulting from a two-point testcross will be

Correct Answer
verified

If 156 tetrads are analyzed following a series of two-point testcrosses in Neurospora, and 102 of them are PD, 40 are T, and the remaining 14 are NPD, what is the frequency of recombination between the two genes?

Correct Answer
verified
The recombination frequency is...
View Answer

In the life cycles of yeast and Chlamydomonas, the haploid vegetative cells never undergo fusion to form a diploid cell.

Correct Answer
verified

How can you calculate the recombination frequency between a and b in the previous question?

In the yeast Saccharomyces cerevisiae, when an MATa mating type fuses with a MATα mating type, the resulting cell is diploid.

Correct Answer
verified

In order to use tetrad analysis in an organism to map the distance between a gene and the centromere on a chromosome,

Correct Answer
verified

During the analysis of an ordered tetrad, 22 percent of the asci showed second-division segregation for a particular genetic locus. What is the distance between the gene and the centromere?

Correct Answer
verified
Eleven map...
View Answer

DNA markers allow genetic mapping in humans on the basis of molecular phenotypes, rather than outwardly visible phenotypes.

Correct Answer
verified

At what stage may mitotic recombination occur?

Correct Answer
verified
When homologs align ...
View Answer

Explain how the two formulas for determining the distance between linked genes in diploid organisms and in tetrad analysis relate to each other.

Following a series of two-point testcrosses in Neurospora, 200 tetrads were analyzed. Of these, 100 were PD and 100 were NPD. These two genes are

Correct Answer
verified

X-linked genes in humans are easier to study than autosomal genes because

Correct Answer
verified

How does the arrangement of ascospores in the tetrads of yeast differ from that in Neurospora crassa?

Correct Answer
verified
The ascospores in a tetrad of yeast are unordered (random), whereas those of Neurospora are linearly ordered.

Describe the possible tetrad types resulting from a cross qr × q+r+ in which the genes are located on separate chromosomes.

Correct Answer
verified
Depending on the metaphase alignment of ...
View Answer

Exam 7: Chromosomal Basis of Inheritance

One map unit on a human chromosome corresponds roughly to

Correct AnswerverifiedShow Answer

What process observed by Curt Stern resulted in twin spot formation in Drosophila?

Correct AnswerverifiedShow Answer

Neurospora crassa, a mycelial-form fungus, is useful for genetic and biochemical studies because it

Correct AnswerverifiedShow Answer

A polymorphic DNA marker is one in which more than one type of sequence is found in the population at that site in the genome.

Correct AnswerverifiedShow Answer

What are heterokaryons?

Correct AnswerverifiedThey are fungal cells in which...View AnswerShow Answer

Mitotic rather than meiotic recombination analysis has been used to construct genetic maps in the fungus Aspergillus.

Correct AnswerverifiedShow Answer

If two genes are linked, then the frequency of parental ditype tetrads resulting from a two-point testcross will be

Correct AnswerverifiedShow Answer

If 156 tetrads are analyzed following a series of two-point testcrosses in Neurospora, and 102 of them are PD, 40 are T, and the remaining 14 are NPD, what is the frequency of recombination between the two genes?

Correct AnswerverifiedThe recombination frequency is...View AnswerShow Answer

In the life cycles of yeast and Chlamydomonas, the haploid vegetative cells never undergo fusion to form a diploid cell.

Correct AnswerverifiedShow Answer

How can you calculate the recombination frequency between a and b in the previous question?

In the yeast Saccharomyces cerevisiae, when an MATa mating type fuses with a MATα mating type, the resulting cell is diploid.

Correct AnswerverifiedShow Answer

In order to use tetrad analysis in an organism to map the distance between a gene and the centromere on a chromosome,

Correct AnswerverifiedShow Answer

During the analysis of an ordered tetrad, 22 percent of the asci showed second-division segregation for a particular genetic locus. What is the distance between the gene and the centromere?

Correct AnswerverifiedEleven map...View AnswerShow Answer

DNA markers allow genetic mapping in humans on the basis of molecular phenotypes, rather than outwardly visible phenotypes.

Correct AnswerverifiedShow Answer

At what stage may mitotic recombination occur?

Correct AnswerverifiedWhen homologs align ...View AnswerShow Answer

Explain how the two formulas for determining the distance between linked genes in diploid organisms and in tetrad analysis relate to each other.

Following a series of two-point testcrosses in Neurospora, 200 tetrads were analyzed. Of these, 100 were PD and 100 were NPD. These two genes are

Correct AnswerverifiedShow Answer

X-linked genes in humans are easier to study than autosomal genes because

Correct AnswerverifiedShow Answer

How does the arrangement of ascospores in the tetrads of yeast differ from that in Neurospora crassa?

Correct AnswerverifiedThe ascospores in a tetrad of yeast are unordered (random), whereas those of Neurospora are linearly ordered.

Describe the possible tetrad types resulting from a cross qr × q+r+ in which the genes are located on separate chromosomes.

Correct AnswerverifiedDepending on the metaphase alignment of ...View AnswerShow Answer

Correct Answer
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verified
They are fungal cells in which...
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Correct Answer
verified

Correct Answer
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verified
The recombination frequency is...
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Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
Eleven map...
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Correct Answer
verified

Correct Answer
verified
When homologs align ...
View Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
The ascospores in a tetrad of yeast are unordered (random), whereas those of Neurospora are linearly ordered.

Correct Answer
verified
Depending on the metaphase alignment of ...
View Answer