Question

Write the base sequence of the DNA template from which this RNA sequence was derived: GUAUCAAUGAACUUG. How many amino acids are coded for in this sequence?

Short answer

The DNA base sequence is 'CATAGTTTCTTGAAC'. The sequence codes for 5 amino acids.

Step-by-step solution

- Understanding DNA and RNA Complementation

DNA and RNA sequences are complementary to each other. Adenine (A) pairs with Uracil (U) in RNA and Thymine (T) in DNA, while Cytosine (C) pairs with Guanine (G).

- Identify the RNA Sequence

The given RNA sequence is: GUAUCAAUGAACUUG

- Determine the Complementary DNA Sequence

Using base pairing rules, convert the RNA sequence back to the DNA template strand:G (RNA) -> C (DNA)U (RNA) -> A (DNA)A (RNA) -> T (DNA)C (RNA) -> G (DNA)A (RNA) -> T (DNA)A (RNA) -> T (DNA)U (RNA) -> A (DNA)G (RNA) -> C (DNA)A (RNA) -> T (DNA)A (RNA) -> T (DNA)C (RNA) -> G (DNA)U (RNA) -> A (DNA)U (RNA) -> A (DNA)G (RNA) -> C (DNA)This results in the DNA sequence: CATAGTTTCTTGAAC

- Count the Codons in the RNA Sequence

Each codon in the RNA sequence codes for one amino acid, and a codon is made of three nucleotides. Divide the RNA sequence into codons:GUA - UCA - AUG - AAC - UUGThere are 5 codons.

- Determine the Number of Amino Acids

Since each codon codes for one amino acid, the number of amino acids coded in the RNA sequence is equal to the number of codons identified.

Key concepts

base pairing rules

DNA and RNA are made up of four nucleotides each. They form the basis of genetic information and follow specific pairing rules for accurate duplication and expression. In DNA, the nucleotides are Adenine (A), Thymine (T), Cytosine (C), and Guanine (G). In RNA, Thymine is replaced by Uracil (U). The base pairing rules ensure that the genetic code is accurately transferred from DNA to RNA during transcription and further processed during translation.
In summary:
• In DNA: A pairs with T, and C pairs with G
• In RNA: A pairs with U, and C pairs with G
These complementary pairing rules are essential for processes like DNA replication and RNA synthesis.
For instance, if you have a short sequence of DNA like ACGT, the complementary RNA sequence would be UGCA.

codons

A codon is a sequence of three nucleotides in RNA that corresponds to a specific amino acid or a start/stop signal during protein synthesis. Codons are fundamental to translating the genetic code into functional proteins.
For example:
• The RNA sequence GUA codes for the amino acid Valine.
• UCA codes for Serine.
The genetic code is virtually universal, meaning the same codons code for the same amino acids across almost all organisms. This universality underscores the fundamental unity of life.
To read codons, scientists generally use a codon table which helps to quickly determine the amino acid for each codon.
Remember, reading the RNA sequence GUAUCAAUGAACUUG as codons results in:
• GUA
• UCA
• AUG
• AAC
• UUG
This breakdown indicates five separate codons, each coding for a different amino acid.

amino acid coding

The genetic code uses sequences of three nucleotides, known as codons, to specify each amino acid in a protein. This is crucial because proteins are made up of long chains of amino acids, and the order of these amino acids determines a protein's structure and function.
Amino acids are organic compounds essential for life, and there are 20 different types that are coded by different codons.
For example:
• GUA codes for Valine.
• AUG is a special codon because it signals the start of translation and also codes for Methionine.
Understanding how a sequence of RNA gets translated into a sequence of amino acids is fundamental for comprehending how genes dictate the traits of an organism.
It is also important to note that some RNA sequences (codons) do not code for amino acids but serve as signals to start or stop the translation process. These are known as the start and stop codons.
In our sequence GUAUCAAUGAACUUG:
• AUG is a start codon.
• The sequence can be broken into five codons, each which will be translated into a corresponding amino acid.