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Zorluk: OrtaCell Biology, Genetics, and Evolution

Consider the following statements regarding the fundamental properties of the genetic code in molecular biology:

1. The genetic code is degenerate, meaning that a single amino acid can be specified by more than one codon.
2. The codon AUG possesses a dual function, coding for the amino acid methionine as well as acting as the initiator codon.
3. The genetic code is ambiguous, meaning that a particular triplet codon can code for several different amino acids depending on cellular conditions.

Which of the statements given above is/are correct?

  1. A
    2 and 3 only
  2. B
    1 and 3 only
  3. 1 and 2 onlyCevap
  4. D
    1, 2 and 3

Cevap

1 and 2 only
The combination '1 and 2 only' is correct because the genetic code exhibits degeneracy (61 sense codons coding for 20 amino acids) and AUG serves a dual role as both an initiator codon and the codon for methionine. In contrast, the genetic code is non-ambiguous because each codon specifies precisely one amino acid.

Adım Adım Çözüm

1
Evaluate statement 1 regarding genetic code degeneracy.
Statement 1 is correct.
There are 64 codons and only 20 standard amino acids. Most amino acids are coded by more than one triplet codon (for example, leucine and arginine are specified by six different codons each), which defines the degenerate nature of the genetic code.
2
Evaluate statement 2 regarding the functions of the AUG codon.
Statement 2 is correct.
AUG acts as the universal start codon that initiates translation in polypeptide synthesis, and it also incorporates the amino acid methionine into the growing polypeptide chain.
3
Evaluate statement 3 regarding the specificity and unambiguity of the genetic code.
Statement 3 is incorrect.
The genetic code is unambiguous and specific, meaning that one specific codon codes for one and only one amino acid. It is never ambiguous.
4
Synthesize the evaluations to select the matching statement combination.
Only statements 1 and 2 are correct.
Combining the valid statements yields '1 and 2 only'.

Anahtar Kavram

Properties of the Genetic Code: Degeneracy, Unambiguity, and Initiation Codons
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Konular

Cell Biology, Genetics, and Evolution

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