4th test mastering & DSM unsure Flashcards
What is the definition of a map unit? See Section 5.2.
1% recombinant products of meiosis
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
b. parental combinations of alleles
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
a. crossing over
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?
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
genetic linkage
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?
linkage disequilibrium
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?
No conclusion can be made regarding the linkage of N and H.
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?
16%
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?
0.52
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?
12 red eye, vestigial wing
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?
12.5% or 1/8
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%?
80
Which of the following statements about gene linkage is true?
If syntenic genes exhibit linkage, parental gametes occur more frequently than nonparental gametes.
Which of the following best describes the inheritance pattern of VNTRs?
VNTRs exhibit codominance
Which of the following statements describes the relationship between the calculated map distances and the actual physical distances?
The calculated map distance usually underestimates the physical distance between genes because of undetected double crossovers.
You have a patient diagnosed with Williams–Beuren syndrome. What would you expect to see in their karyotype analysis?
Chromosome 7 with a nonfunctional hybrid PMSA-PMSB gene, and a deletion of the PMSA, PMSB, and the 17 genes between them.
Which human condition is the result of uniparental disomy?
Prader-Wili syndrome
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?
One cell will be monosomic (2n-1 or 2n= 39), and the other will be trisomic (2n+1 or 2n= 41).
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?
Allohexaploid
Studies of infants born with Down syndrome have established that over 90% of cases can be attributed to what chromosomal abnormality?
Maternal meiosis I nondisjunction of chromosome 21
Which gene is responsible for aniridia, one of the symptoms of WAGR syndrome?
PAX6
Where would you expect to see nonhistone proteins anchoring chromatin loops to the scaffold?
MARs
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
two haploid gametes fuse to form a diploid cell
How many chromosomes would be found in an allopolyploid plant if its parents had diploid numbers of 4 and 6 respectively?
5
What phenotype would be expected in balanced translocation heterozygotes in the absence of position effects?
Normal, because they have a normal amount of genetic material
A Robertsonian translocation is considered non-reciprocal because _______.
the smaller of the two reciprocal products of translocated chromosomes is lost
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?
6
Which of the following arrangements would yield the greatest reduction in gamete viability?
An inversion heterozygote for a large inversion
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?
2546
