Ch.17 Nucleic Acids and Protein Synthesis

Timberlake - Chemistry: An Introduction to General, Organic, and Biological Chemistry 14th Edition

Timberlake14th EditionChemistry: An Introduction to General, Organic, and Biological ChemistryISBN: 9781292472249Not the one you use?Change textbook

Timberlake 14th Edition

Ch.17 Nucleic Acids and Protein Synthesis

Problem 117

Chapter 17, Problem 117

Endorphins are polypeptides that reduce pain. What is the amino acid order for the endorphin leucine enkephalin (leu-enkephalin), which has the following mRNA?
AUG UAC GGU GGA UUU CUA UAA

Verified step by step guidance

Step 1: Understand the problem. The question asks for the amino acid sequence of leucine enkephalin based on the provided mRNA sequence. To solve this, we need to translate the mRNA codons into their corresponding amino acids using the genetic code.

Step 2: Break the mRNA sequence into codons. Codons are groups of three nucleotides. The given mRNA sequence is AUG UAC GGU GGA UUU CUA UAA. Divide it into codons: AUG, UAC, GGU, GGA, UUU, CUA, UAA.

Step 3: Use the genetic code to translate each codon into its corresponding amino acid. For example: AUG codes for Methionine (start codon), UAC codes for Tyrosine, GGU codes for Glycine, GGA codes for Glycine, UUU codes for Phenylalanine, CUA codes for Leucine, and UAA is a stop codon.

Step 4: Assemble the amino acid sequence. Exclude the stop codon (UAA) as it signals the end of translation. The sequence of amino acids before the stop codon forms the polypeptide chain.

Step 5: Verify the sequence and ensure it matches the expected structure of leucine enkephalin. Double-check each codon translation and confirm the order of amino acids.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Endorphins

Endorphins are a group of polypeptides produced by the body that function as neurotransmitters. They are primarily known for their role in pain relief and the regulation of mood, often referred to as 'feel-good' hormones. Endorphins bind to opioid receptors in the brain, reducing the perception of pain and promoting feelings of pleasure or euphoria.

mRNA and Codons

Messenger RNA (mRNA) is a type of RNA that carries genetic information from DNA to the ribosome, where proteins are synthesized. The sequence of nucleotides in mRNA is read in sets of three, known as codons, each of which corresponds to a specific amino acid. Understanding the codon sequence is essential for determining the amino acid order in a protein, such as leucine enkephalin.

Amino Acid Sequence

The amino acid sequence of a protein is determined by the order of codons in the mRNA. Each codon specifies a particular amino acid, and the sequence ultimately dictates the protein's structure and function. For leucine enkephalin, translating the mRNA sequence into its corresponding amino acids is crucial for understanding its biological role and properties.

Endorphins are polypeptides that reduce pain. What is the amino acid order for the endorphin leucine enkephalin (leu-enkephalin), which has the following mRNA?AUG UAC GGU GGA UUU CUA UAA