genes located on the same chromosome, which may assort independently or exhibit genetic linkage
What is meant by syntenic genes?
ABC, ABc, aBC, aBc
What possible gametes will be produced from a parent who has the genotype AaBBCc, assuming the three genes are NOT syntenic?
EF/ef or eF/ef
You set up a cross between two parents, EeFF and eeff. What would the dihybrid F1 progeny look like from this cross if there is complete genetic linkage?
B-A-C-D
It is true that Gene A will be closest to Gene B and Gene C will be closest to Gene D, because they have very small recombination frequencies. Note that the recombination frequency between B and C is 35% and the recombination frequency between A a
Given the following recombination frequencies, what is the predicted order of the genes? Gene A and Gene B = 1% Gene C and Gene B = 35% Gene C and Gene A = 34% Gene D and Gene C = 4% Gene D and Gene A = 38%
18.3 cM
Recombination frequency is proportional to the percentage, and 45.2 ? 26.9 = 18.3 cM
In the map of the Drosophila X chromosome, the recombination frequency between vermillion and rudimentary is 26.9%, and the distance between white and rudimentary is 45.2%. If you know that the order of the genes is w-v-r, how far apart are white and verm
7
df = n ? 1, where n = number of phenotypic classes. In the case of a trihybrid cross, how many possible phenotypes would you expect to see?
For a given trihybrid cross (looking at three different genes), you want to calculate the chi-square value to establish possible linkage. How many degrees of freedom would you use to determine the p value?
This result indicates a significant deviation between observed and expected results, suggesting that the genes are linked.
For a given dihybrid cross with an expected ratio of 1:1:1:1, you calculate the chi-square value and compare it to the chi-square table to determine your p value. What would a p value of p << 0.005 tell you about the two genes?
eight genetically different gamete genotypes, but with parental genotypes seen more frequently than the nonparental genotypes
In a trihybrid cross, you expect to see how many possible genotypes (2n)
What types of gametes would you expect if you have incomplete genetic linkage of three genes in a trihybrid cross?
a+b+cd or abc+d+
If you have a cross between two parents with the genotypes a+b+c+d+/ abcd and abcd / abcd, which of the following represents a single crossover gamete with crossover between genes b and c?
a+bcd+
If you have a cross between two parents with the genotypes a+b+c+d+/ abcd and abcd / abcd, which of the following represents a double crossover gamete in which there has been crossover between genes a and b, and between c and d?
0.08, or 8%
The expected double-crossover frequency is the product of the two single-crossover frequencies
The probability of one single crossover event is 20%, and that of the other single crossover is 40%. If each crossover event is independent, what is the expected number of double crossover events?
0.714
You observe five double crossovers among 100 test-cross progeny, or 5%. If the two single-crossover frequencies are 0.2 and 0.35, what is the coefficient of coincidence (c)?
0.166
Interference identifies the proportion of double recombinants that are expected but are not seen in the experiment. I = 1 ? c, where c = 10/12. Thus, 1 ? 0.833 = 0.166.
If the observed double-crossover events are 10/200 and you expect 12/200, what is the percentage of double crossovers that are expected but NOT seen in this experiment?
40%
For a dihybrid organism AB/ab, the frequency of the Ab gamete is 10%. What is the frequency of the AB gamete?
0.28
For a trihybrid organism ABC/abc, the probability of NO crossovers between genes a and b is 80% (0.8), and the probability of NO crossovers between b and c is 70% (0.7). What is the frequency of each parental gamete?
0.07
For a trihybrid organism ABC/abc, the probability of NO crossovers between genes a and b is 80% (0.8), and the probability of NO crossovers between b and c is 70% (0.7). What is the frequency of the Abc gamete?
at the four-strand stage, when each member of a homologous chromosome pair is composed of two sister chromatids
At what point during the cell cycle does genetic recombination occur?
The lod score will be positive if the likelihood of genetic linkage is greater than the likelihood of independent assortment.
What does a positive lod score analysis tell you about gene relationships?
0.36
Two sample haplotypes for the same region on homologous chromosomes are denoted as ...A? B C? D E F?... ...A B? C D? E? F ... Assume that the frequencies of alleles at the genes are A = 0.60 and B = 0.10. What is the predicted frequency of the A? B? haplo
PD and NPD tetrads containing 50% parental gametes and 50% nonparental gametes
If NO crossing over has occurred and two chromosomes exhibit proper segregation and independently assortment, what types of ascospores would you expect to see?