Question

If an mRNA molecule synthesized in the laboratory consists only of adenine and guanine in an approximate \(2: 1\) ratio, what possible amino acids could be included in the polypeptide to be produced?

Short answer

The possible amino acids in the polypeptide produced from the laboratory-synthesized mRNA molecule with adenine (A) and guanine (G) in a 2:1 ratio include Lysine (Lys), Arginine (Arg), and Glutamic Acid (Glu). This is based on the possible codon combinations of AAG, AGA, and GAA and their corresponding amino acids in the genetic code.

Step-by-step solution

Determine possible codons

We have a 2:1 ratio of adenine (A) and guanine (G) nucleotides in the mRNA molecule. A codon consists of three nucleotides and we can have the following combinations of A and G (taking into account the ratio): 1. AAG 2. AGA 3. GAA

Use the genetic code to match codons to amino acids

Now, we will use the genetic code to match each codon to its corresponding amino acid. The genetic code is as follows: - AAG = Lysine (Lys) - AGA = Arginine (Arg) - GAA = Glutamic Acid (Glu)

List possible amino acids in the polypeptide

Based on the possible codons and their corresponding amino acids from the given mRNA molecule, the polypeptide produced could include the following amino acids: 1. Lysine (Lys) 2. Arginine (Arg) 3. Glutamic Acid (Glu)

Key concepts

mRNA

Messenger RNA or mRNA is a fundamental component in the translation of genetic information from DNA into proteins. During this process, mRNA is synthesized using a DNA strand as a template, a method known as transcription. mRNA serves as a temporary copy, carrying the genetic instructions from the nucleus to the ribosome, where proteins are synthesized.

The sequence of nucleotides in mRNA, which includes adenine (A), guanine (G), cytosine (C), and uracil (U), determines the sequence of amino acids in a protein. This nucleic acid sequence is crucial because any change or mutation can lead to an altered protein, potentially affecting its function.

• mRNA is like a messenger that brings the code for making proteins from DNA in the nucleus to the ribosome.
• It is composed of four bases: A, G, C, and U, which are arranged in sequences called codons.

Codons

Codons are sequences of three nucleotides in mRNA that specify which amino acid will be added next during protein synthesis. Each codon consists of three consecutive nucleotides, and there are 64 possible codon combinations. Although there are only 20 amino acids, multiple codons can code for the same amino acid, a feature called redundancy.

For example, let’s consider the codons from our exercise: AAG, AGA, and GAA. Each of these codons maps to a specific amino acid:

• AAG = Lysine (Lys)
• AGA = Arginine (Arg)
• GAA = Glutamic Acid (Glu)

Understanding codons is key to understanding how genetic information is translated into the diverse proteins necessary for life.

Amino Acids

Amino acids are the building blocks of proteins, which are essential molecules in all living organisms. Each amino acid consists of a basic amino group (-NH2), an acidic carboxyl group (-COOH), and a unique side chain that determines its properties. There are 20 different amino acids, each contributing distinct characteristics to proteins.

In the protein synthesis process, the sequence of codons in mRNA directs the order in which amino acids are added to the growing polypeptide chain. This sequence is vital since it defines the protein's structure and function.

• Lysine (Lys) is a basic amino acid, crucial for protein structure and immune function.
• Arginine (Arg) is involved in cell division and wound healing.
• Glutamic Acid (Glu) is important for cognitive function and metabolism.

Without accurate transcription and translation, the resulting protein might not function correctly, illustrating the precision of genetic coding.