Question

In: Biology

In the Jubjub bird, the gene G controls feather color. The dominant allele G gives rise...

In the Jubjub bird, the gene G controls feather color. The dominant allele G gives rise to black pigmentation, and the recessive allele g gives rise to a pale gray color when homozyous. The gene D regulates size. The dominant allele D gives rise to giant jubjubs with wingspans over 5 meters, and dwarfism, with wingspans averaging 3 meters, is recessive. The ability to talk is also recessive. The dominant allele of the T locus results in mute birds. A single female jubjub bird can lay a clutch of over 900 eggs. A fully heterozygous female was mated with a dwarf, gray male who could talk. The offspring were counted. Please indicate whether any or all of these genes assort independently of one another. Map any linked loci.

Color Adult Size Speech Number of Offspring
Black Giant Mute 5
Black Giant talking 17
Black dwarf Mute 0
Black dwarf talking 361
gray Giant Mute 379
gray Giant talking 0
gray dwarf Mute 14
gray dwarf talking 6

Solutions

Expert Solution

Answer:

All genes are present in the same chromosome and they are not at all assorted independently.

Gene map:

G----------1.22 mu--------T-----------3.44 mu--------------D

Explanation:

Based on the information, the cross is test cross. If the genes are not linked and they are assorted independently, the trihybrid testcross ratio is “1:1:1:1:1:1:1:1”

But the number of offspring produced is not in the ratio mentioned above. Therefore the genes are linked.

Hint: Always recombinant genotypes are smaller than the non-recombinant genotypes.

Hence, the parental (non-recombinant) genotypes is Gdt/gDT

Color

Adult Size

Speech

Number of Offspring

Genotype

Black

Giant

Mute

5

GDT

Black

Giant

talking

17

GDt

Black

Dwarf

Mute

0

GdT

Black

Dwarf

Talking

361

Gdt

gray

Giant

Mute

379

gDT

gray

Giant

Talking

0

gDt

gray

Dwarf

Mute

14

gdT

gray

Dwarf

Talking

6

gdt

1).

If single crossover occurs between G&d..

Normal combination: Gd/gD

After crossover: GD/gd

GD progeny= 5+17=22

gd progeny = 6+14=20

Total this progeny = 42

The recombination frequency between G&d = (number of recombinants/Total progeny) 100

RF = (42/900)100 = 4.67%

2).

If single crossover occurs between d & t..

Normal combination: dt/DT

After crossover: dT/Dt

dT progeny= 14+0=14

Dt progeny = 17+0=17

Total this progeny = 31

The recombination frequency between d&t = (number of recombinants/Total progeny) 100

RF = (31/900)100 = 3.44%

3).

If single crossover occurs between G&t

Normal combination: Gt/gT

After crossover: GT/gt

GT progeny= 5+0=5

gt progeny = 6+0=6

Total this progeny = 11

The recombination frequency between G&t = (number of recombinants/Total progeny) 100

RF = (11/900)100 = 1.22%

Recombination frequency (%) = Distance between the genes (mu)

G----------1.22 mu--------T-----------3.44 mu--------------D

All genes are present in the same chromosome and they are not at all assorted independently.


Related Solutions

The black color cost in hamsters is due to a dominant gene (B).. A recessive allele...
The black color cost in hamsters is due to a dominant gene (B).. A recessive allele (b) at this locus results in a brown coat when homozygous (b/b). However, neither coat color is expressed when the organism is homozygous for the allele (a) at a separate locus. The a/a genotype results in a white (albino) coat, regardless of the allele at the B locus. The wild-type allele (+) at the (a) locus allows normal coat coloration, whether the genotype is...
In dogs, the allele for black coat color (B) is dominant to the allele for brown...
In dogs, the allele for black coat color (B) is dominant to the allele for brown coat color (b). But if a dog has two copies of the recessive allele for a pigment-depositing gene (e), it can only have yellow coat color. In a cross of two doubly heterozygous black dogs (BbEe x BbEe), what fraction of the next generation would we expect to be yellow? WHY? a.1/8 b.1/4 c.2/3 d.3/16
In mice the allele for black coat color (B) is dominant to the allele for white...
In mice the allele for black coat color (B) is dominant to the allele for white coat color (b). The allele for long tail (T) is dominant to the allele for short tail (t). For the same cross: BbTt x bbTt     a. Using the Probability Method illustrated in lecture, break the complex two-gene cross into two simple single-gene crosses (note that the Probability Method can be used if it is known that the alleles of the different genes Assort...
In a population of mealybugs the dominant allele (G) frequency for an allele controlling fluffiness is...
In a population of mealybugs the dominant allele (G) frequency for an allele controlling fluffiness is 0.75. Selection is acting upon this locus such that the fitness values are gg=0.4, Gg=1, and GG=0.027. Simulate selection in the population by calculating gentoype frequencies following selection, and calculating allele frequencies from those genotype frequencies. a. State which genotype is being favored by selection. b. Give the normalized/corrected genotype frequency for gg following selection. Round your answer to the nearest thousandth (e.g., 0.123)...
In Drosophila the gene for red eyes is dominant over the gene cinnabar eye color, the...
In Drosophila the gene for red eyes is dominant over the gene cinnabar eye color, the gene for gray body color over the genome of the black color of the body, the gene for normal wings – on the genome of rudimentary wings. All the genes are on the same chromosome. After crossing a homozygous female Drosophila with red eyes (cn+), gray body (b+) and normal wings (vg+) with a homozygous recessive male with cinnabar eyes (cn), black body (b)...
In a certain species of flower, the red allele for flower color (R) is completely dominant...
In a certain species of flower, the red allele for flower color (R) is completely dominant to the pink allele (r). A completely recessive allele (d) at a second gene on a different chromosome allows pigment (color) to be actually deposited within flowers; the lack of pigment results in white flowers. READ CAREFULLY! (a) What is a possible genotype for a pink flower? ___ ___ ___ ___ (b) What is the probability that a flower that is heterozygous for both...
Here is a data set on bird populations with color variation. The Y gene is autosomal...
Here is a data set on bird populations with color variation. The Y gene is autosomal with a Y allele (yellow plumage) and y allele (brown plumage), where Y is dominant to y (Y > y). The survey shows phenotypic frequencies for a large mainland population on the coast of Ecuador and a small island population. The island population was founded in 1960 by a small flock of birds. Thereafter, there has been some gene flow between the mainland and...
how can a loss-of-function allele in a gene encoding the cohesin protein could be dominant to...
how can a loss-of-function allele in a gene encoding the cohesin protein could be dominant to the wild type allele ?
Consider the gene for the character “freckles”. We’ll use “F” to designate the dominant allele (which...
Consider the gene for the character “freckles”. We’ll use “F” to designate the dominant allele (which produces freckles), and “f” to designate the recessive allele (no freckles). ​​​a. Suppose one parent has freckles. What are the possible genotypes for that parent? ____________________ ​​​b. Suppose one parent has no freckles. What do we know about that parent’s genotype? ___________________ ​​​c. If the parent with freckles is homozygous (FF), what proportion of offspring will have freckles? ​​​​A) None of them ​​​​B) 25%...
Suppose two genes determine shape and color of peas. Gene G codes for color and G...
Suppose two genes determine shape and color of peas. Gene G codes for color and G is dominant. A pea that is GG or Gg is green, a pea that is gg is yellow. The gene R codes for shape. A pea that is RR or Rr is round, a pea that is rr is oval. If we cross two peas that are Gg and Rr we expect the following distribution of peas: (9/16) are green and round, (3/16) are...
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT