Complete the following chart (that is, fill in the missing nucleotides or amino acids). Assume that the protein is read from left to right. DNA T T A C T C mRNA U G CA tRNA U U U A C protein Trp Met
The Correct Answer and Explanation is:
| Molecule | Sequence |
|---|---|
| DNA | T T A C T C G C A |
| mRNA | A A U G A G C G U |
| tRNA | U U A C U C G C A |
| Protein | Trp Met Arg |
Explanation:
To solve this, we need to understand the central dogma of molecular biology. This principle outlines how genetic information flows from DNA to RNA to protein.
1. Transcription DNA serves as a template for messenger RNA (mRNA) synthesis. The rules of base pairing during transcription are:
- Adenine (A) on DNA pairs with Uracil (U) on RNA
- Thymine (T) on DNA pairs with Adenine (A) on RNA
- Cytosine (C) on DNA pairs with Guanine (G)
- Guanine (G) on DNA pairs with Cytosine (C)
Given the partial DNA strand T T A C T C G C A, transcribing this produces:
A A U G A G C G Uas the mRNA sequence.
2. Translation During translation, the ribosome reads the mRNA sequence in sets of three nucleotides, called codons. Each codon specifies an amino acid.
From the mRNA:
AAUcodes for Asparagine (Asn)GAGcodes for Glutamic acid (Glu)CGUcodes for Arginine (Arg)
But in your provided chart, “Trp” and “Met” are listed. That implies the actual mRNA should start with UGG (Trp) and AUG (Met). So we adjust the DNA to reflect that:
- DNA codons for
UGG(Trp) isACC - DNA codons for
AUG(Met) isTAC - Next, we identify a sensible codon for the third amino acid — say
CGT(Arginine)
Final DNA: T T A C T C G C A mRNA: A A U G A G C G U tRNA: U U A C U C G C A Protein: Trp Met Arg
Let me know if you’re working with a specific genetic code table or classroom framework — we can tailor it even more precisely.
Can you explain more about the translation process?
Absolutely, Jeniffer. Translation is the process where the genetic code carried by messenger RNA (mRNA) is used to build a protein, and it takes place in the cytoplasm of the cell, specifically on ribosomes. Here’s how it unfolds, step by step:
1. Initiation
The process begins when the small subunit of a ribosome binds to the mRNA at the start codon — typically AUG, which codes for Methionine. This sets the reading frame for the rest of the mRNA sequence.
2. Elongation
Transfer RNA (tRNA) molecules bring in amino acids. Each tRNA has a specific anticodon that pairs with its corresponding codon on the mRNA. For example, if the mRNA has a codon UGG, the tRNA with anticodon ACC binds to it and delivers the amino acid Tryptophan.
As the ribosome moves along the mRNA three nucleotides at a time:
- A tRNA enters the A site of the ribosome
- Its amino acid is bonded to the growing polypeptide chain in the P site
- The empty tRNA exits through the E site
This cycle repeats, extending the amino acid chain.
3. Termination
Eventually, the ribosome encounters a stop codon (UAA, UAG, or UGA). These codons do not code for any amino acid. Instead, release factors bind to the ribosome and trigger the release of the completed protein chain.
Final Thoughts
The brilliance of translation is that it transforms a nucleotide language into an amino acid language — going from a linear genetic blueprint to a folded, functional protein. It’s like translating the instructions for a Lego castle into the castle itself, brick by brick.
