Question

In a mixed copolymer experiment, messages were created with either \(4 / 5 \mathrm{C}: 1 / 5 \mathrm{A}\) or \(4 / 5 \mathrm{A}: 1 / 5 \mathrm{C}\). These messages yielded proteins with the amino acid compositions shown in the following table. Using these data, predict the most specific coding composition for each amino acid. $$\begin{array}{lccc} {}{} {4 / 5 \mathrm{C}: 1 / 5 \mathrm{A}} & {}{} {4 / 5 \mathrm{A}: 1 / 5 \mathrm{C}} \\ \text { Proline } & 63.0 \% & \text { Proline } & 3.5 \% \\ \text { Histidine } & 13.0 \% & \text { Histidine } & 3.0 \% \\ \text { Threonine } & 16.0 \% & \text { Threonine } & 16.6 \% \\ \text { Glutamine } & 3.0 \% & \text { Glutamine } & 13.0 \% \\ \text { Asparagine } & 3.0 \% & \text { Asparagine } & 13.0 \% \\ \text { Lysine } & \underline{0.5 \%} & \text { Lysine } & \underline{50.0 \%} \\\ & 98.5 \% & & 99.1 \% \end{array}$$

Short answer

Answer: The predictions are as follows: - Proline: More reliant on C - Histidine: More reliant on C - Threonine: Evenly reliant on C and A - Glutamine: Evenly reliant on C and A - Asparagine: Evenly reliant on C and A - Lysine: More reliant on A

Step-by-step solution

Identify the amino acids with higher occurrence in each message

Compare the percentages of each amino acid in both messages: Message 1 (4/5 C: 1/5 A): Proline 63%, Histidine 13%, Threonine 16%, Glutamine 3%, Asparagine 3%, Lysine 0.5% Message 2 (4/5 A: 1/5 C): Proline 3.5%, Histidine 3%, Threonine 16.6%, Glutamine 13%, Asparagine 13%, Lysine 50% From the comparison, we can see that Proline and Histidine are much more prominent in message 1 compared to message 2, whereas Lysine is much more prominent in message 2 compared to message 1.

Determine the coding compositions based on nucleotide contribution

Since Proline and Histidine are more prominent in message 1, where C is more abundant, it is reasonable to infer that the coding composition for these amino acids is more reliant on C than on A. Similarly, because Lysine is much more prominent in message 2, where A is more abundant, it is likely that the coding composition for Lysine is more reliant on A than on C. Threonine, Glutamine, and Asparagine have roughly similar proportions in each message, indicating that their coding compositions are likely more evenly dependent on both C and A.

Predict the specific coding compositions for each amino acid

Based on the conclusions from Step 2, we can predict the most specific coding compositions for each amino acid: - Proline: More reliant on C - Histidine: More reliant on C - Threonine: Evenly reliant on C and A - Glutamine: Evenly reliant on C and A - Asparagine: Evenly reliant on C and A - Lysine: More reliant on A These predictions provide a rough estimate of the coding compositions for each amino acid in these messages; however, more detailed analysis or experimental data would be necessary to accurately determine individual nucleotide codes for each amino acid.

Key concepts

Copolymer Experiment

In genetic research, a copolymer experiment is an intriguing method to decipher how nucleotides code for proteins. This type of experiment involves creating synthetic sequences of nucleotides in known proportions to observe the resulting protein production. By varying the ratio of nucleotides, scientists can examine how different codon sequences affect amino acid formation, which helps in #understanding how the genetic code translates RNA sequences into proteins.
This particular experiment used two sets of nucleotide mixtures: one with a ratio of 4:1 of Cytosine (C) to Adenine (A) and another the reverse, with a ratio of 4:1 of A to C.
These mixtures were then used to synthetic DNA or RNA templates, and the resulting protein outputs showcased variations in amino acid composition. Such experiments highlight the significance of nucleotide sequences in coding specific amino acids and give essential insights into the translation process.

Amino Acid Coding

Amino acid coding refers to how sequences of three nucleotides, known as codons, on messenger RNA (mRNA) specify particular amino acids during protein synthesis. Each of the 20 standard amino acids has its unique codons, some of which are more frequent depending on the organism or context.
In this experiment, variations in amino acid presence, such as Proline being more prevalent in the C-rich copolymer, suggest that some amino acids indeed depend more heavily on specific nucleotides. This is crucial for understanding genetic coding because if a particular amino acid shows a high percentage in one nucleotide mixture but not in another, it implies a specific nucleotide's stronger influence in its coding.
The analysis of variations in amino acid prevalence when nucleotide proportions are altered helps scientists deduce which codons and bases are likely involved in the synthesis of each amino acid. Thus, breaking down the genetic code, one step at a time.

Nucleotide Contribution

Understanding nucleotide contribution is key in predicting amino acid coding from nucleotide sequences. Nucleotides, the building blocks of RNA and DNA, each have a part to play in coding sequences that produce proteins. These sequences dictate the arrangement of amino acids, which are essential for protein function.
Different nucleotides' contributions are discerned by comparing how changes in nucleotide ratios affect which amino acids are produced in copolymer experiments.
For example, in the discussed experiment, C's higher contribution led to more proline and histidine, showing its dominance in coding these amino acids. On the contrary, lysine increased significantly with more A contribution, reflecting its heavier dependency on adenine.
This valuable insight helps researchers narrow down possible codon options for amino acids, aligning closely with biological processes in cells.

Protein Synthesis

Protein synthesis is a fundamental biological process where cells create proteins based on genetic instructions carried by mRNA. It involves two main stages: transcription and translation:

• **Transcription:** The DNA is transcribed into mRNA, capturing the genetic code. The resulting mRNA strand carries this information out of the cell's nucleus and into the ribosomes, the cell's protein factories.
• **Translation:** At the ribosomes, the process of translation begins. Here, ribosomal RNA (rRNA) and transfer RNA (tRNA) work together to read the mRNA codons and assemble the appropriate amino acids into a polypeptide chain.

In the copolymer experiment, studying protein synthesis focuses on how artificial sequences affect which proteins are synthesized.
Understanding this process helps decode the genetic language into practical applications in biotechnology and medicine. By manipulating nucleotide compositions, scientists can see how changes impact the synthesis process, enhancing our grasp of gene expression and protein function.