Two viral genomes are sequenced, and the following percentages of...

Question

Two viral genomes are sequenced, and the following percentages of nucleotides are identified:

Genome 1:  A = 28%,  C = 22%, G = 28%, T = 22%
Genome 2:  A = 22%,  C = 28%, G = 28%, T = 22%

Are the DNA molecules in each genome single stranded or double stranded?

Accepted Answer

Hi, everyone. Let's look at our next question, which of the following statements is explained best using Char Gaff's rule. Choice A, the base pairs with the most hydrogen bonds are complementary to each other. Choice B the base pairs with the fewest Tito gen bonds are complementary to each other. Choice C, if the percentage of two bases are equal to each other, then they are complementary to each other. Or choice D, if the percentage of two bases are unequal to each other, then they are complementary to each other. Well, let's think about Char Gaff's rule and remember what it tells us and it has kind of two elements the first being, but the amounts of the bases T and A are equal in a DNA molecule and the amounts of C and G are equal in a DNA molecule. So that's sort of part one of char gas rule. And then part two of char gas rule says that pyrimidines and purines are present in a DNA molecule in a 1 to 1 ratio and pyrimidines being T and C pines being A and G. So with that in mind, let's look at those answer choices Choi says the base pairs with the most hydrogen bonds are complimentary each other, complimentary to each other. While B says the base pairs with the fewest hydrogen bonds are complimentary to each other. Well, neither of these is something that's explained by Kuchar Gaff's rule because neither is quite completely correct. Um Because we have two sets of bases, obviously, they're complimentary T and A and they form two hydrogen bonds. Meanwhile, our second set of complementary base C and G form three hydrogen bonds. So they have different numbers of hydrogen bonds, but both are complementary pairs. So it doesn't matter whether there's more or few, less or fewer hydrogen bonds, they're both complementary. Then cho C says, if the percentage of two bases are equal to each other, then they are complementary to each other. And this is the answer we're looking for because understanding that those T and A bases are found in equal amounts and the same with C and G lends us to the knowledge that they are complementary base pairs in that double helical structure, they always come together in a pair. And then choice D obviously says, if the 2% of two bases are unequal to each other, then they are complimentary. And that's not our answer because since they are complimentary and come bound together in pairs, they need to be present in equal amounts. So again, which of the following statements is explained best using Char Gaff's rule choice C if the percentage of two bases are equal to each other, then they are complementary to each other. See you in the next video.

Two viral genomes are sequenced, and the following percentages of nucleotides are identified: Genome 1: A = 28%, C = 22%, G = 28%, T = 22% Genome 2: A = 22%, C = 28%, G = 28%, T = 22% Are the DNA molecules in each genome single stranded or double stranded?

Key Concepts

Base Pairing Rules

Nucleotide Composition

Single-Stranded vs. Double-Stranded DNA

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