Concept explainers
(a)
To describe: The conclusion which is obtained from the nondisjunction and recombination frequencies and the way by which trisomic frequencies are influenced by the recombination frequencies
Introduction: The chromosomes are small structures which carry genes. These chromosomes transfer from one generation to another and show the similarity in the progeny. There are 23 pairs of chromosomes found in a cell.
(b)
To describe: The selective advantage of positive chromosomal interference
Introduction: The chromosomes carry genetic information of an organism. These are thread-like structures which are found in the nucleus of the cell. The traits of an organism are carried by the chromosomes from one generation to another.
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Concepts of Genetics (11th Edition)
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- Imagine a scenario in which prenatal testing of a human female fetus indicates that the baby will have a normal XX karyotype but is heterozygous for a mutation that inactivates the Xist promoter. Allele “Xr” represents the mutated version of the Xist promoter, and “XR” represents the normal version of the Xist promoter. How will this mutation affect the process of X inactivation?A. "X inactivation will still be random with both mutant and normal X chromosomes being randomly inactivated" B. "The chromosome with the mutant Xist promoter will always be active" C. "The chromosome with the mutant Xist promoter will always be inactivated" D. "The normal X chromosome (no mutation in Xist) will always be active" E. "The normal X chromosome (no mutation in Xist) will always be inactivated"arrow_forwardExplain the following: a- No parental type is produced during gametogenesis? b- A dominant wild type produced a sign spot in Drosophila? c- 9:7 phenotypic ratio is produced in dihybrid cross? d- 50% parental type gametes were produced during gametogenesis? e- All recombinant gametes were produced during gametogenesis?arrow_forwardUsing the figure and the following background information answer the following questions about the figure Background: Identification of the genetic cause of hornlessness in cattle has been the subject of intensive genetic and genomic research, culminating in the nomination of two different candidate neomutations on cattle chromosome 1 that are predicted to have arisen 500-1,000 years ago: a complex allele of Friesian origin (PF), an 80,128 base pair (bp) duplication (1909352-1989480 bp), and a second, simple allele of Celtic origin (PC) corresponding to a duplication of 212 bp (chromosome 1 positions 1705834-1706045) in place of a 10-bp deletion (1706051-1706060)We report the use of genome editing using transcription activator-like effector nucleases (TALENs) to introgress the putative PC POLLED allele into the genome of bovine embryo fibroblasts to try and produce a genotype identical to what is achievable using natural mating, but without the attendant genetic drag and admixture. In…arrow_forward
- The mutations called bobbed in Drosophila result from variable reductions (deletions) in the number of amplified genes coding for rRNA. Researchers trying to maintain bobbed stocks have often documented their tendency to revert to wild type in successive generations. Propose a mechanism based on meiotic recombination which could account for this reversion phenomenon. Why would wild-type flies become more prevalent in Drosophila cultures?arrow_forwardFemales of wild-type Strain A and males of mutant Strain B, as well as females of mutant Strain B and males of wild-type Strain A, make reciprocal crosses. Explain why reciprocal crosses are needed in genetics experiments involving Drosophila fruit flies.arrow_forwardmapping three linked genes, the heterozygous AaBbCc was crossed to aabbcc individual the following phenotypes were obtained: ABC 4 abc 2 ABc 150 abC 141 aBc 18 AbC 20 Abc 30 aBC 35 A) What are the alleles found on each parental chromosome(genotypes of the parents)? B) How many double recombinants(cross over) were there? c) what is the linear arrangement of loci on the chromosome?arrow_forward
- What is a meaning of genetic linkage? How this test is used? Describe the meaning of SNP (single nucleotide polymorphisms) and genetic distance identification which is used in genetic analysis. Knowing that recombination events occur more or less at random along the length of chromosomes, in which case the recombination will occur more frequently between the genes during meiosis: if two genes are closer together two genes are far away from each other there is no impact based on location of two genes. What is a definition of DNA polymorphism and how can this be used for linkage studies? What is a definition of DNA polymorphism and how can this be used for linkage studies?arrow_forwardHomozygous wild-type male mice (AA BB CC) were crossed with triplemutant female mice (aa bb cc), forming an F1 generation with the followinggenotype (Aa Bb Cc). The F1 males were crossed with triple mutantfemales, forming the following F2 phenotypes”“a B c” 3“A b C” 3“a b c” 8“A B c” 5“a b C” 5“A B C” 8“a B C” 6“A b c” 6 44 Determine the sequence of the genesarrow_forward. With regards to the grasshopper testes experiment, diakinesis is an ideal stage to determine chromosome number due to the degree of condensation of the chromosomes? Count the chromosomes at this stage. Does it represent a diploid or a haploid number?arrow_forward
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