4th test mastering & DSM unsure

Question 1

What is the definition of a map​ unit? See Section 5.2.

Answer 1

​1% recombinant products of meiosis

Question 2

Genetic linkage leads to the production of a significantly greater than expected number of gametes containing chromosomes with​ ________.
a. mutant alleles
b. parental combinations of alleles
c. recessive alleles
d. allele combinations that are different from parental combinations
e. dominant alleles

Answer 2

b. parental combinations of alleles

Question 3

Alleles of linked genes usually segregate together during meiosis. When they​ don’t, it is because​ ________ has occurred between them.
a. crossing over
b. duplication
c. linkage disequilibrium
d. mutation

Answer 3

a. crossing over

Question 4

Two​ genes, A and X​, exhibit incomplete linkage. The frequency of each parental gamete ​(AX and ax​) is​ 45%. What is the approximate frequency of the Ax​ gamete?

Answer 4

5%

Question 5

What is observed when syntenic genes are close enough to one another that they are unable to assort​ independently?
single nucleotide polymorphisms
recombination
genetic linkage
linkage equilibrium

Answer 5

genetic linkage

Question 6

If too little time has passed for crossing over to randomize haplotypes or if natural selection favors certain​ haplotypes, what would you expect to​ see?

Answer 6

linkage disequilibrium

Question 7

The Zmax from the analysis of a disease gene N and the DNA marker H was 2.5 at theta ​= 0.1. Which of the following is the best interpretation of this​ result?

Answer 7

No conclusion can be made regarding the linkage of N and H.

Question 8

A patient has a disease-causing allele, D, and the genotype A1B1D / A2B2d. You are trying to decide if this haplotype can be used to predict the inheritance of the allele, D, in this patient’s children. First, you need to decide how often crossing over occurs between these genetic markers to decide if it will work. The distance between A and B is 20 cM, and between B and D is 15 cM. What is the probability of an affected individual inheriting a recombinant haplotype with the disease-causing allele?

Answer 8

16%

Question 9

An organism of the genotype a+b+c+/abc was testcrossed to a triply recessive organism, abc/abc. The phenotypic classes of the progeny are as follows:

28 a+b+c+

27 abc

10 a+bc

12 ab+c+

9 a+b+c

11 abc+

1 a+bc+

2 ab+c

What is the coefficient of coincidence?

Answer 9

0.52

Question 10

In one of Morgan’s test-crosses, he crossed pr+ vg+ / pr vg females with recessive males. Assuming you collect 100 offspring, which of the following results would indicate genetic linkage between these two genes?

Answer 10

12 red eye, vestigial wing

Question 11

An individual has a genotype AaBbCc, where ABC and abc are the parental gametes. What is the predicted frequency of the AbC nonparental gamete, assuming no linkage?

Answer 11

12.5% or 1/8

Question 12

In a sample of 500 gametes from an organism with the genotype CD/cd, how many gametes would you expect to have the genotype Cd, assuming crossover is 32%?

Answer 12

80

Question 13

Which of the following statements about gene linkage is true?

Answer 13

If syntenic genes exhibit linkage, parental gametes occur more frequently than nonparental gametes.

Question 14

Which of the following best describes the inheritance pattern of VNTRs?

Answer 14

VNTRs exhibit codominance

Question 15

Which of the following statements describes the relationship between the calculated map distances and the actual physical distances?

Answer 15

The calculated map distance usually underestimates the physical distance between genes because of undetected double crossovers.

Question 16

You have a patient diagnosed with Williams–Beuren syndrome. What would you expect to see in their karyotype analysis?

Answer 16

Chromosome 7 with a nonfunctional hybrid PMSA-PMSB gene, and a deletion of the PMSA, PMSB, and the 17 genes between them.

Question 17

Which human condition is the result of uniparental disomy?

Answer 17

Prader-Wili syndrome

Question 18

Mice have 40 chromosomes (2n = 40). Suppose a cell undergoing mitosis experiences a chromosome nondisjunction of a single chromosome. What are the chromosome numbers in the resulting daughter cells?

Answer 18

One cell will be monosomic (2n-1 or 2n= 39), and the other will be trisomic (2n+1 or 2n= 41).

Question 19

Bread wheat, Triticum aestivum, is a cultivated wheat species with two sets of chromosomes from three different species. What term describes this type of polyploidy?

Answer 19

Allohexaploid

Question 20

Studies of infants born with Down syndrome have established that over 90% of cases can be attributed to what chromosomal abnormality?

Answer 20

Maternal meiosis I nondisjunction of chromosome 21

Question 21

Which gene is responsible for aniridia, one of the symptoms of WAGR syndrome?

Answer 21

PAX6

Question 22

Where would you expect to see nonhistone proteins anchoring chromatin loops to the scaffold?

Answer 22

MARs

Question 23

All of the following events occur during normal meiosis except​ _______.

one diploid cell produces four haploid cells
two haploid gametes fuse to form a diploid cell
sister chromatids separate from one another during meiosis II
homologous chromosomes separate from one another during meiosis I

Answer 23

two haploid gametes fuse to form a diploid cell

Question 24

How many chromosomes would be found in an allopolyploid plant if its parents had diploid numbers of 4 and 6​ respectively?

Answer 24

5

Question 25

What phenotype would be expected in balanced translocation heterozygotes in the absence of position​ effects?

Answer 25

​Normal, because they have a normal amount of genetic material

Question 26

A Robertsonian translocation is considered​ non-reciprocal because​ _______.

Answer 26

the smaller of the two reciprocal products of translocated chromosomes is lost

Question 27

With respect to the chromosomes involved in the​ translocation, 14 and​ 21, what is the total number of different gametes possible for a heterozygous carrier parent to​ produce?

Answer 27

6

Question 28

Which of the following arrangements would yield the greatest reduction in gamete​ viability?

Answer 28

An inversion heterozygote for a large inversion

Question 29

Referring to the​ image, there appears to be a span of 13​ “beads” present. Ignoring the DNA before the first bead and after the 13th​ bead, how much DNA is present in the​ photo?

Answer 29

2546