교과서 질문
An organism having the genotype AaBbCcDdEe is self-fertilized. Assuming the five genes assort independently, determine the following proportions:
Progeny that are expected to have a phenotype identical to that of the parent.
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3. Extensions to Mendelian Inheritance
Understanding Independent Assortment
Multiple Choice
A sample of DNA contains 10% guanine. What percentage of the DNA is composed of adenine?
A
10%
B
40%
C
30%
D
20%
검증된 단계별 안내1
Recall Chargaff's rules, which state that in double-stranded DNA, the amount of guanine (G) equals the amount of cytosine (C), and the amount of adenine (A) equals the amount of thymine (T). This means \(\%G = \%C\) and \(\%A = \%T\).
Given that guanine makes up 10% of the DNA, use Chargaff's rule to determine that cytosine also makes up 10%. So, \(\%G = 10\%\) and \(\%C = 10\%\).
Calculate the combined percentage of guanine and cytosine: \(\%G + \%C = 10\% + 10\% = 20\%\).
Since the total percentage of all four bases must add up to 100%, subtract the combined G and C percentage from 100% to find the combined percentage of adenine and thymine: \(100\% - 20\% = 80\%\).
Finally, because adenine and thymine are present in equal amounts, divide the combined A and T percentage by 2 to find the percentage of adenine: \(\%A = \frac{80\%}{2}\).
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