Ch. 5 - Genetic Linkage and Mapping in Eukaryotes

Sanders - Genetic Analysis: An Integrated Approach 3rd Edition

Sanders3rd EditionGenetic Analysis: An Integrated ApproachISBN: 9780135564172당신이 사용하는 게 아니라요?교과서 변경

Sanders 3rd Edition

Ch. 5 - Genetic Linkage and Mapping in Eukaryotes

문제 35b

5장, 문제 35b

Based on previous family studies, an autosomal recessive disease with alleles A and a is suspected to be linked to an RFLP marker. The RFLP marker has four alleles, R₁, R₂, R₃, and R₄. The accompanying pedigree shows a three-generation family in which the disease is present. The gel shows the RFLP alleles for each family member directly below the pedigree symbol for that person. After determining the genotypes for the RFLP and disease gene for each family member, answer the following questions.

Is there any evidence of recombination in this pedigree? If so, identify the recombinant individuals and illustrate the recombination that has occurred.

검증된 단계별 안내

Step 1: Understand the problem. The question involves determining whether recombination has occurred between an autosomal recessive disease gene (A/a) and an RFLP marker with four alleles (R₁, R₂, R₃, R₄). Recombination refers to the exchange of genetic material between homologous chromosomes during meiosis, which can result in new allele combinations.

Step 2: Analyze the pedigree and gel electrophoresis data. Begin by identifying the genotypes for the disease gene (A/a) and the RFLP marker (R₁, R₂, R₃, R₄) for each individual in the pedigree. Use the gel bands to determine the RFLP alleles and the inheritance pattern of the disease gene to deduce the A/a genotypes.

Step 3: Determine the parental haplotypes. For each parent, identify the combination of disease gene allele (A or a) and RFLP marker allele (R₁, R₂, R₃, or R₄) that they pass to their offspring. This will help establish the original linkage phase (non-recombinant haplotypes).

Step 4: Compare offspring genotypes to parental haplotypes. For each child in the pedigree, check whether their combination of disease gene allele and RFLP marker allele matches one of the parental haplotypes. If it does not match, this indicates a recombination event.

Step 5: Identify recombinant individuals and illustrate recombination. List the individuals whose genotypes show evidence of recombination. For each recombinant individual, describe the specific recombination event (e.g., which alleles were exchanged) and illustrate it using a diagram or written explanation of the crossover event between homologous chromosomes.

비슷한 문제에 대한 검증된 영상 답변:

이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.

영상 길이:

도움이 되었나요?

주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Autosomal Recessive Inheritance

Autosomal recessive inheritance refers to a pattern where two copies of a mutated gene (one from each parent) are necessary for an individual to express a trait or disease. In this case, alleles A (normal) and a (mutated) determine the presence of the disease. Individuals with genotype aa will exhibit the disease, while those with AA or Aa will be unaffected. Understanding this inheritance pattern is crucial for analyzing the pedigree and determining which individuals may carry the disease allele.

Restriction Fragment Length Polymorphism (RFLP)

RFLP is a molecular technique used to analyze the variations in DNA sequences by digesting DNA with specific restriction enzymes, resulting in fragments of different lengths. These variations can serve as genetic markers, helping to track inheritance patterns in families. In this scenario, the RFLP marker with alleles R₁, R₂, R₃, and R₄ is used to identify potential linkage to the autosomal recessive disease, providing insight into the genetic relationships among family members.

Recombination

Recombination is the process by which genetic material is exchanged between homologous chromosomes during meiosis, leading to new allele combinations in offspring. This can result in recombinant individuals who possess a mix of alleles from both parents. In the context of the pedigree and RFLP analysis, identifying recombinant individuals involves comparing the alleles present in offspring with those of their parents to determine if any new combinations have arisen, indicating that recombination has occurred.

관련 실천

교과서 질문

The accompanying pedigree below shows a family in which an autosomal recessive disorder is present. Family members I-2 and II-2 are affected by the disorder and have the genotype dd. A pregnancy involving II-4 has just undergone genetic testing for a VNTR that is linked to the disease gene. The VNTR has a recombination frequency of r = 20 with the disease gene. The VNTR has two alleles, V₁ and V₂. The gel electrophoresis patterns for each family member are shown, including the VNTR genotype for II-4. Based on the information given, answer the following questions about the family.

What are the syntenic disease gene and VNTR alleles in I-1 and I-2?

655

views

교과서 질문

For six genes known to be linked on chromosome 10 of corn (Zea mays), the recombination frequencies between various pairs have been determined in a series of genetic crosses. Use the recombination frequency data in the table below to determine the order of and distance between the genes on a genetic map. The gene lc1 is known to be closest to the telomere of the chromosome.

621

views

교과서 질문

Based on previous family studies, an autosomal recessive disease with alleles A and a is suspected to be linked to an RFLP marker. The RFLP marker has four alleles, R₁, R₂, R₃, and R₄. The accompanying pedigree shows a three-generation family in which the disease is present. The gel shows the RFLP alleles for each family member directly below the pedigree symbol for that person. After determining the genotypes for the RFLP and disease gene for each family member, answer the following questions.

What is the most likely arrangement of syntenic alleles for the RFLP and the disease gene in I-1 and I-2?

854

views

교과서 질문

Based on your analysis, what is the recombination frequency in this family? Explain how you obtained your answer.

457

views

교과서 질문

What is the chance II-4 has the disease?

516

views

교과서 질문

Divide a clean sheet of paper into four quadrants and draw one pair of homologous chromosomes in each quadrant. Draw the chromosomes with two sister chromatids each. The four sets of homologous pairs are identical. Label one chromosome of each pair with alleles A₁ and A₂ and the other member of each pair with the alleles A₁ and A₂. You are to illustrate a single crossover between the homologs in each quadrant and list the parental and recombinant chromosomes, but you are to illustrate four different ways the crossover can occur by involving different chromatids in each illustration.

452

views