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During the 1950's, several scientists were responsible for discovering the structure of DNA. One scientist, Erwin Chargaff, found that in DNA, the ratios of adenine (A) to thymine (T) and guanine (G) to cytosine (C) are always equal. Select the answer choice that was NOT indicated by Chargaff's discovery about the structure of DNA and its impact on replication. Responses A Adenine pairs with thymine; guanine with cytosine.Adenine pairs with thymine; guanine with cytosine. B The base pairing facilitates DNA replication and RNA transcription.The base pairing facilitates DNA replication and RNA transcription. C When pairing nucleotides, you must pair purines with purines and pyrimidines with pyrimidines.When pairing nucleotides, you must pair purines with purines and pyrimidines with pyrimidines. D If we read the sequence of nucleotides on one strand of DNA, we can identify the complementary sequence on the other strand.If we read the sequence of nucleotides on one strand of DNA, we can identify the complementary sequence on the other strand. Question 2 All organisms contain DNA, and every organism's DNA is made of the same four nucleotides. The differences between organisms is simply based on the order of these nucleotides. Since all organisms have the same basic, universal structure for DNA, which of these must also be universal? Responses A All organisms have the same proteins.All organisms have the same proteins. B All living things must have the same amount of DNA.All living things must have the same amount of DNA. C The codons in all organisms' DNA code for the same amino acids.The codons in all organisms' DNA code for the same amino acids. D The DNA blueprint varies based on how the nucleotides pair during replication.

1 answer

For the first question regarding Chargaff's discovery, the correct choice that was NOT indicated is:

C When pairing nucleotides, you must pair purines with purines and pyrimidines with pyrimidines.

Chargaff's rules indicate that adenine pairs with thymine and guanine pairs with cytosine, which is consistent with purines (A and G) pairing with pyrimidines (T and C), rather than purines being paired with each other.

For the second question, the correct choice that must also be universal among all organisms is:

C The codons in all organisms' DNA code for the same amino acids.

This statement is true because the genetic code is universal for all living organisms, meaning that the same codon will code for the same amino acid across different species. Meanwhile, options A and B are not true, as organisms can have entirely different proteins and varying amounts of DNA. Option D also holds true only for specific cases rather than universally across all organisms.