4. Consider the imaginary linked genes A and B in Neurospora.
35% of meioses display no crossover.
35% have one crossover in the region between the genes.
30% have two crossovers in the region between the genes.
a. What is the predicted recombination frequency? Show your work, including the formula used to calculate the recombination frequency.
Answer:
b. Which tetrad type numbers in the progeny should be compared to determine if genes in Neurospora are linked? Explain why.
Answer:
Can you please help me out?
4. Consider the imaginary linked genes A and B in Neurospora.
35% of meioses display no crossover.
35% have one crossover in the region between the genes.
30% have two crossovers in the region between the genes.
a. What is the predicted recombination frequency? Show your work, including the formula used to calculate the recombination frequency.
Answer:
b. Which tetrad type numbers in the progeny should be compared to determine if genes in Neurospora are linked? Explain why.
Answer:
Can you please help me out?
Related textbook solutions
Related questions
My prof says this is done wrong as the break point is between R and Y. Could you please help me out? With explanation? Thank you!
10. In a certain plant, a dominant allele for one gene, R, produces round fruit and the recessive allele, r, produces oblong fruit. A dominant allele of a second gene, Y, produces yellow flowers and the recessive allele, y, produces white flowers. The two genes are linked on chromosome IV. A plant (r y/r y) with normal chromosomes is crossed to a plant (R Y/R Y) homozygous for a reciprocal translocation between chromosomes IV and VIII. The presence of the translocation causes semi-sterility. The F1 progeny are phenotypically yellow flowered with round fruit and are semi-sterile. A backcross to the parent with normal chromosomes yields the 750 progeny shown in the table below.
| Number of Progeny | ||
| Fertile | Semi-sterile | |
| Yellow, round | 3 | 283 |
| White, oblong | 295 | 2 |
| Yellow, oblong | 73 | 12 |
| White, round | 10 | 72 |
a. From these data, draw a map showing all relevant map distances (in centimorgans) for the genes and the translocation breakpoint. Show your work.
Answer:
Cross over gametes: Yellow, oblong & White, round
Total number of Progeny = 381
Frequency of cross over gametes=
83 / 381 = .22 Morgans
22 cM
85 / 369 = .23 Morgans
23 cM
The genes are located on the same side of the chromosome.
Break point R Y
. . 22cM .
No; the breakpoint is located between the two genes. Also you muat use both classes of dluble crossovers to calculate the two intervals. Please redo
b. Briefly explain the basis of the semi-sterility of translocation-bearing plants.
Answer: The semi-sterility in F1 plants are caused by reciprocal translocation. As the organism is heterozygous for reciprocal translocation meaning that offsprings are produced less than normal. This reciprocal translocation may have occurred at meiosis during chromosome segregation. No; the translocation already existed.
Please read your text and redo 3/10
Please show detailed work. Thanks in advance.
16. Syntenic genes can assort independently when
A) they are very close together on a chromosome.
B) they are located on different chromosomes.
C) crossing over occurs rarely between the genes.
D) they are far apart on a chromosome and crossing over occurs frequently between the genes.
E) they are far apart on a chromosome and crossing over occurs very rarely between the genes.
17. The alleles of linked genes tend to
A) segregate together more often than expected by random assortment
B) assort independently.
C) be mutated more often than unlinked genes.
D) experience a higher rate of crossing over.
E) assort independently and show a higher rate of crossing over.
18. If you know that the frequency of recombination between genes X and Y is 34% and between X and Z is 25%, can you predict the order of the three genes?
A) Yes; the order is X-Z-Y.
B) Yes; the order is X-Y-Z.
C) Yes; the order is Z-X-Y.
D) No; based on this data alone, the order could be Z-Y-X or X-Y-Z.
E) No; based on this data alone, the order could be X-Z-Y or Z-X-Y.
Question 19 - 20. You have performed the following dihybrid cross in Drosophila using the black body color (b) and vestigial wing (vg) mutations. The b+ (grey body) and vg+ (normal wing) are dominant wild type alleles. These genes are autosomal.
Female â b+ vg+/b vg à male â b vg/b vg
Progeny:
Phenotype # of Progeny
Grey body normal wing 965
Black body vestigial wing 944
Grey body vestigial wing 208
Black body normal wing 195
19. Assuming linkage between black and vestigial, the estimated recombination frequency would be:
0.17
0.09
0.82
1.00
0.50
20. What key test could you use to determine whether the observed offspring frequencies deviate from those expected by chance alone?
A) Pascal's triangle
B) The product rule
C) The Chi-square (Ï2) test
D) The law of random assortment
E) The sum rule
21. In a genome wide association study (GWAS) designed to map the gene(s) that control height you divide subjects into a group of 1000 who are all more than seven feet tall and a control group of 1000 people of average height. You find the following associations between two genetic markers and the height trait:
| Tall group | Control group | ||
| Marker 1 | Allele A | 20% | 50% |
| Allele T | 80% | 50% | |
| Marker 2 | Allele G | 15% | 15% |
| Allele C | 85% | 85% |
What is your best guess for which marker is more closely linked to a gene that influences height?
A) Marker 1
B) Marker 2
22. Two pure breeding parents produce red and white flowers. They are crossed and the F1 produces pink flowers. When the F1 are selfed to produce the F2, nine distinct classes of pigmentation are present among F2 individuals. What is your best guess of the minimum number of genes that underlie flower pigmentation in this species?
A. 2
B. 3
C. 4
D. 5
E. 6
23. In a quantitative genetic experiment you identify two genes that confer bands of color on the back of a fly. At each gene, a dominant allele causes one band of color. If flies that are heterozygous at both loci are crossed, what ratio of offspring do you expect in each phenotype (i.e., number of color bands) class? (answer options are given from lowest to highest band number)
A) 1:1:1:1:1
B) 1:2:2:2:1
C) 1:4:6:4:1
D) 4:4:4:4:4
