Ch. 9 - The Molecular Biology of Translation

Sanders - Genetic Analysis: An Integrated Approach 3rd Edition

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

Sanders 3rd Edition

Ch. 9 - The Molecular Biology of Translation

문제 B.6c

9장, 문제 B.6c

A couple and some of their relatives are screened for Gaucher disease in a community-based screening program. The woman is homozygous for the dominant allele, represented by G. The woman's father, sister, and paternal grandmother are heterozygous carriers of the mutant allele, represented by g. Her paternal grandfather, her mother, and both of her mother's parents are homozygous for the dominant allele. The man is heterozygous and he has a brother with Gaucher disease. The man's parents and grandparents have not been tested, but it is known that none of them has Gaucher disease.
Explain why you are able to assign genotypes to the man's parents despite their not being tested.

검증된 단계별 안내

Recall that Gaucher disease is typically inherited in an autosomal recessive manner, meaning that an individual must have two copies of the mutant allele (gg) to express the disease phenotype.

Since the man's brother has Gaucher disease, he must be homozygous recessive (gg), which means both parents must have contributed a mutant allele to him.

Because the parents do not have Gaucher disease themselves, they cannot be homozygous recessive (gg); therefore, each parent must be heterozygous carriers (Gg) of the mutant allele.

This reasoning allows us to assign the genotype Gg to both of the man's parents, even though they have not been tested, because they must each carry one mutant allele to have an affected child.

The fact that none of the man's grandparents have Gaucher disease supports the idea that the mutant allele is present in a heterozygous state in the parents, as the disease is recessive and would manifest only if two copies of the mutant allele were inherited.

비슷한 문제에 대한 검증된 영상 답변:

이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.

영상 길이:

주요 개념

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

Autosomal Recessive Inheritance

Gaucher disease is inherited in an autosomal recessive manner, meaning an individual must inherit two copies of the mutant allele (gg) to express the disease. Carriers (Gg) have one normal and one mutant allele but do not show symptoms. Understanding this pattern helps infer genotypes based on affected or unaffected status within a family.

Genotype Inference from Phenotype and Family History

Even without direct testing, genotypes can be deduced by analyzing the presence or absence of disease in relatives. Since the man is heterozygous (Gg) and has an affected brother (gg), both parents must carry at least one mutant allele, making them obligate carriers (Gg), despite no symptoms.

Dominant vs. Recessive Allele Notation and Interpretation

In this question, the dominant allele (G) is normal, and the recessive allele (g) causes disease when homozygous. Recognizing the difference between dominant and recessive alleles and their phenotypic effects is essential to correctly assign genotypes and understand inheritance patterns.

관련 실천

교과서 질문

Identify the amino acid carried by tRNAs with the following anticodon sequences.

5′-UAG-3′

411

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교과서 질문

Describe three features of tRNA molecules that lead to their correct charging by tRNA synthetase enzymes.

1365

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교과서 질문

A couple and some of their relatives are screened for Gaucher disease in a community-based screening program. The woman is homozygous for the dominant allele, represented by G. The woman's father, sister, and paternal grandmother are heterozygous carriers of the mutant allele, represented by g. Her paternal grandfather, her mother, and both of her mother's parents are homozygous for the dominant allele. The man is heterozygous and he has a brother with Gaucher disease. The man's parents and grandparents have not been tested, but it is known that none of them has Gaucher disease.

On the pedigree, write the genotypes (GG, Gg, or gg) for each person who has been tested or for whom you can deduce a genotype. If a genotype cannot be determined completely, list the alleles you know or deduce must be present.

387

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교과서 질문

A portion of a DNA template strand has the base sequence

5′-...ACGCGATGCGTGATGTATAGAGCT...-3′

Assume the mRNA is written in the correct reading frame. Determine the amino acid sequence encoded by this fragment. Identify the N- and C-terminal directions of the polypeptide.

716

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교과서 질문

Draw a pedigree of this family, including the woman, the man, their siblings, parents, and grandparents.

377

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교과서 질문

A portion of a DNA template strand has the base sequence

5′-...ACGCGATGCGTGATGTATAGAGCT...-3′

Which is the third amino acid added to the polypeptide chain?

651

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