Before the genetic code was actually known, Francis Crick predicted that it was degenerate. What piece of evidence led him to make this prediction? Question 18 options: 1) All proteins looked the same. 2) All proteins were made of amino acids. 3) He noted that the base composition of the DNAs of various bacteria varied greatly while the amino acid composition of their proteins varied very little overall. 4) He noted that the base composition of the DNAs of various bacteria varied little while the amino acid composition of their proteins varied greatly overall. 5) The code was nonoverlapping.
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Before the genetic code was actually known, Francis Crick predicted that it was degenerate. What piece of evidence led him to make this prediction? (Hint: You don't have to know what Crick was thinking, just what answer would support degeneracy of the genetic code?) a) All proteins looked the same. b) The code was non-overlapping. c) He noted that the base composition of the DNAs of various bacteria varied little while the amino acid composition of their proteins varied greatly overall. d) He noted that the base composition of the DNAs of various bacteria varied greatly while the amino acid composition of their proteins varied very little overall. e) All proteins were made of amino acids.
Adi S.
a) This observation can be explained by the fact that the genetic code is degenerate, meaning that multiple codons can code for the same amino acid. Therefore, even though the nucleotide sequences of the two bacteria species are not identical, they can still code for the same protein if the codons used are different but still code for the same amino acids. This is known as synonymous mutations. b) This observation suggests that nucleotide similarity searches may not be as effective as amino acid similarity searches in identifying related genes. While nucleotide sequences can provide information about the overall genetic similarity between organisms, they do not necessarily reflect the functional similarity of the proteins encoded by those genes. Amino acid similarity searches, on the other hand, directly compare the protein sequences and can identify proteins that have similar functions even if their nucleotide sequences are not highly similar. Therefore, amino acid similarity searches may be more reliable in identifying related genes with similar functions.
Which of the following BEST explains why a single base substitution in a gene-coding region for amino acids will sometimes lead to no change in amino acid sequence? a. All nucleotides are subject to the same mutation rate b. Some nucleotide bases are covalently joined by stronger bonds c. The code is degenerate with more than one triplet coding for the same amino acid d. Some amino acids act in the same fashion in determining the tertiary structure of a protein The packaging, sorting & exporting organelle of the cell: a. Golgi Bodies b. Lysosomes c. Ribosomes d. Mitochondria
Maitreya E.
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