Skip to main content
Ch. 25 - Quantitative Genetics and Multifactorial Traits

Chapter 24, Problem 5

The use of nucleotide sequence data to measure genetic variability is complicated by the fact that the genes of many eukaryotes are complex in organization and contain 5' and 3' flanking regions as well as introns. Researchers have compared the nucleotide sequence of two cloned alleles of the γ-globin gene from a single individual and found a variation of 1 percent. Those differences include 13 substitutions of one nucleotide for another and three short DNA segments that have been inserted in one allele or deleted in the other. None of the changes takes place in the gene's exons (coding regions). Why do you think this is so, and should it change our concept of genetic variation?

Verified Solution
Video duration:
1m
This video solution was recommended by our tutors as helpful for the problem above.
216
views
Was this helpful?

Video transcript

Hello everyone and welcome to today's video. So, genetic variation within a species is contributed by different factors which of the following genetic variation sources is attributed to changes in the sequences of the genes in DNA. So it is something that is at the molecular level. Let's go over each other answer choices so that we may solve the problem beginning by sexual reproduction or sexual reproduction is going to bring on genetic variation by changing the levels of a Leo's or use a ratio of a Leo's in a population by favoring different traits. This is not going to affect the DNA sequence. So we're going to cancel this out, then we have gene flow and this refers to the movement of a Leo's between population. Again, this is not really going to affect a sequence of DNA. So we're also going to cancel it out. Speciation. On the other hand refers to the creation of a new species. Again, here, the D N A sequence is not affected. So we're going to cancel this out and then we have the very popular term mutation. So a mutation refers to a type of change. So imagine that we have a D N A sequence such as this one, we have a C G and then a mutation occurs and this changes to C C G. This mutation change one of the nucleotides in the DNA sequence, which is exactly what the question is asking for. This is the variation that occurred because of this answer. Choice D is going to be the correct answer to our question. I really hope this helped you and I hope to see you on the next one.
Related Practice
Textbook Question

A dark-red strain and a white strain of wheat are crossed and produce an intermediate, medium-red F₁. When the F₁ plants are interbred, an F₂ generation is produced in a ratio of 1 dark-red: 4 medium-dark-red: 6 medium-red: 4 light-red: 1 white. Further crosses reveal that the dark-red and white F₂ plants are true breeding

Predict the outcome of the  and  generations in a cross between a true-breeding medium-red plant and a white plant.

409
views
Textbook Question

Height in humans depends on the additive action of genes. Assume that this trait is controlled by the four loci R, S, T, and U and that environmental effects are negligible. Instead of additive versus nonadditive alleles, assume that additive and partially additive alleles exist. Additive alleles contribute two units, and partially additive alleles contribute one unit to height.

Can two individuals of moderate height produce offspring that are much taller or shorter than either parent? If so, how?

464
views
Textbook Question

Height in humans depends on the additive action of genes. Assume that this trait is controlled by the four loci R, S, T, and U and that environmental effects are negligible. Instead of additive versus nonadditive alleles, assume that additive and partially additive alleles exist. Additive alleles contribute two units, and partially additive alleles contribute one unit to height.

If an individual with the minimum height specified by these genes marries an individual of intermediate or moderate height, will any of their children be taller than the tall parent? Why or why not?

372
views
Textbook Question

An inbred strain of plants has a mean height of 24 cm. A second strain of the same species from a different geographic region also has a mean height of 24 cm. When plants from the two strains are crossed together, the F₁ plants are the same height as the parent plants. However, the F₂ generation shows a wide range of heights; the majority are like the P₁ and F₁ plants, but approximately 4 of 1000 are only 12 cm high and about 4 of 1000 are 36 cm high.

How much does each gene contribute to plant height?

282
views
Textbook Question

An inbred strain of plants has a mean height of 24 cm. A second strain of the same species from a different geographic region also has a mean height of 24 cm. When plants from the two strains are crossed together, the F₁ plants are the same height as the parent plants. However, the F₂ generation shows a wide range of heights; the majority are like the P₁ and F₁ plants, but approximately 4 of 1000 are only 12 cm high and about 4 of 1000 are 36 cm high.

Indicate one possible set of genotypes for the original P₁ parents and the F₁ plants that could account for these results.

196
views
Textbook Question

An inbred strain of plants has a mean height of 24 cm. A second strain of the same species from a different geographic region also has a mean height of 24 cm. When plants from the two strains are crossed together, the F₁ plants are the same height as the parent plants. However, the F₂ generation shows a wide range of heights; the majority are like the P₁ and F₁ plants, but approximately 4 of 1000 are only 12 cm high and about 4 of 1000 are 36 cm high.

Indicate three possible genotypes that could account for F₂ plants that are 18 cm high and three that account for F₂ plants that are 33 cm high.

210
views