Multiple choice help please? 1.Linked genes are arranged with one wild-type alle
ID: 208726 • Letter: M
Question
Multiple choice help please?
1.Linked genes are arranged with one wild-type allele and one mutant allele on one chromosome (w+v) and the other wild-type and other mutant alleles (wv+) are on the homologous chromosome.
beta configuration
trans configuration
cis configuration
genetic recombination
2.
During an experiment you come across an recombination frequency of 50%. What can you conclude about the two loci you are looking at?
They are closely linked
They are X-linked
They are either not linked or far apart from each other
The are on homologous chromosomes
3.
In a mapping experiment with three linked genes, which phenotype should occur most often in the F2 offspring?
Phenotypes of individuals with single crossover events
Parental phenotypes
All of the phenotypes should be equal in the F2 generation
Phenotypes of individuals with double crossover events
4.
Genetic linkage occurs because
genes that are close together on the same chromosome tend to be transmitted together to offspring
genes that are on the same chromosome may affect the same trait
genes that are on different chromosomes are independently assorted
None of the other choices are correct.
5.
Linked genes:
All of the other choices are correct.
are located near each other on the same chromosome
segregate together during meiosis
violate the law of independent assortment
a.beta configuration
b.trans configuration
c.cis configuration
d.genetic recombination
Explanation / Answer
1. Representation of linked genes can be in coupling (cis) or repulsion (trans) configuration. In cis configuration, the wild type alleles are present on one chromosome, while the mutant alleles are present on its homologous chromosomes. In trans configuration, one wild type and one mutant allele is present on one chromosome and the reverse wild type and mutant alleles are present on its homologous chromosome.
Right option is b. Trans configuration.
2. When two genes are present on different chromosomes or are separated widely on the same chromosomes, the genes are non-linked. They will follow the law of independent assortment and will be randomly selected. If this frequency is less than 50%, then the genes are linked genes.
Right option is C. They are either not linked or far apart from each other.
3. When three linked genes (a, b, c) are involved in a crossover , two parental types, four recombinant classes with single cross-overs and two recombinant types showing cross-overs between all three loci will occur. The two parental offsprings will be most abundant. The four single cross-overs will be next abundant. The double cross over recombinant will be the least abundant in the F2 generation. Single cross over will be between any two genes (a-b or b-c) while the double crossover will be between all three genes (a-b-c)
Right option is B. Parental phenotypes.
4. Genetic linkage refers to the phenomena where two genes that are present close to each other are inherited together during meiosis. Genes that are present on different chromosome or far apart from each other are never linked. Linked genes do not follow the Mendalian Law of independent assortment.
Right option is A. genes that are close together on the same chromosome tend to be transmitted together to offspring.
5. Linked genes are genes that are present close to each other on the same chromosomes. They do not follow the Law of independent assortment during meiosis. Hence, they are present in the same gamete as they segregate together during meiosis. They therefore violate the Law of independent assortment.
Right option is All the other choices are correct.
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