Which fundamental cellular activity is directly accomplished by using the genetic code stored in DNA and expressed in messenger RNA?

Introduction / Context:
This question tests your understanding of what biologists mean by the phrase genetic code and at which stage in gene expression that code is actually used. Many learners confuse DNA replication, transcription and translation, so it is important to remember where codons are read and how that reading guides the sequence of amino acids in a protein.

Given Data / Assumptions:
- The genetic code is defined as the set of rules that relate three base codons in messenger RNA to specific amino acids or a stop signal.- The central dogma of molecular biology is DNA to RNA to protein.- The cell carries out DNA replication, transcription and translation using distinct enzymes and structures.- The question asks which activity is directly accomplished using the genetic code.

Concept / Approach:
The genetic code is not a general phrase for any use of DNA. It specifically refers to the correspondence between codons in messenger RNA and amino acids in a polypeptide chain. This mapping is implemented during translation at the ribosome, where transfer RNA molecules match anticodons to codons and deliver the correct amino acids. DNA replication and transcription use base pairing rules, but they do not interpret codons as amino acids. Therefore we look for the option that describes translation of messenger RNA into protein.

Step-by-Step Solution:
Step 1: Recall that the genetic code is a table that shows which three base codon encodes which amino acid or a stop signal.Step 2: Recall that transcription copies a DNA sequence into messenger RNA using base pairing rules, but no amino acids are attached at this stage.Step 3: During translation, the ribosome reads the codons in messenger RNA in the correct reading frame.Step 4: Transfer RNA molecules with complementary anticodons bring the corresponding amino acids according to the genetic code.Step 5: The ribosome joins the amino acids into a polypeptide chain, so translation is the activity directly accomplished by using the genetic code.

Verification / Alternative check:
You can perform a quick check by listing processes that require codons. Only translation requires you to look up each codon in a codon chart.In contrast, replication copies DNA to DNA and transcription copies DNA to RNA without ever consulting a codon table of amino acids.Therefore, the only process that truly uses the genetic code is translation of messenger RNA into protein.

Why Other Options Are Wrong:
Option A is wrong because DNA replication uses complementary base pairing (A with T, G with C) rather than codon to amino acid relationships.Option B is wrong because transcription again uses base pairing to copy DNA into RNA, without interpreting codons as amino acids.Option D is wrong because repair of damaged DNA uses repair enzymes and base pairing but does not involve reading codons as amino acids.Option E is wrong because chromosome segregation in mitosis is a mechanical process involving spindle fibres and has nothing to do with codons or the genetic code.

Common Pitfalls:
A common mistake is to assume that any process involving DNA is an example of the genetic code in action.Learners sometimes think transcription uses the genetic code because both involve RNA, but transcription only copies nucleotide sequences.Another pitfall is to treat the phrase central dogma as if the genetic code applies equally to all stages, which is not correct.

Final Answer:
The activity directly accomplished using the genetic code is the translation of messenger RNA codons into a specific protein at the ribosome.