Problem 5 - Biology Concepts and Applications

Question

Each codon specifies a(n) _____. a. protein b. polypeptide c. amino acid d. mRNA

Step-by-Step Solution

Answer

Each codon specifies an amino acid (c).

Step 1: Understanding the Role of Codons

A codon is a sequence of three nucleotides found in mRNA, which is crucial during the translation phase of protein synthesis.

Step 2: Identifying the Function

During translation, each codon is interpreted by the ribosome to add a specific molecule to the growing polypeptide chain. Codons are instructions for assembling amino acids.

Step 3: Determining the Correct Option

The genetic code is made up of codons that correspond to particular amino acids. Therefore, each codon specifically codes for one of the 20 amino acids that are the building blocks of proteins.

Key Concepts

Understanding Codons

A codon is a trio of nucleotides found in messenger RNA (mRNA). It's essential in translating genetic information into proteins, as it directs the placement of amino acids during protein synthesis. Each codon, consisting of three nucleotides, acts like a coded message that specifies which amino acid will be added next in the sequence of a growing protein. Imagine it like a word in a sentence where each word tells you exactly what comes next. Codons are important because they maintain the integrity of the genetic message by ensuring that amino acids are assembled in the correct order. There are a total of 64 codons, each coding for one of the 20 different amino acids, or serving as a stop signal at the end of protein synthesis.

Amino Acids and Their Significance

Amino acids are the building blocks of proteins. Just as a house is built from individual bricks, proteins are constructed from chains of amino acids. Each amino acid has a specific side chain, known as an R group, which determines its characteristics and role in protein structure and function. There are 20 different amino acids in total, and their sequence in a protein determines the protein's shape and function. Here are some key points about amino acids:

• They have both amine and carboxyl functional groups.
• The side chain (R group) varies among different amino acids.
• The sequence and combination of amino acids contribute to a protein's final structure and role.

When codons are translated, ribosomes link amino acids together in specific sequences to form proteins, emphasizing their importance in genetic expression.

The Process of Protein Synthesis

Protein synthesis is the biological process that cells use to build proteins, crucial for cell function and structure. This process occurs in two main stages: transcription and translation. **Transcription** During transcription, the information in a gene is copied into mRNA. This mRNA travels out of the nucleus and into the cytoplasm, carrying the code needed for protein synthesis. **Translation** Translation is the next step, where ribosomes read the sequence of mRNA codons. Each codon specifies a particular amino acid. Transfer RNA (tRNA) molecules bring the appropriate amino acids to the ribosome where they are added to a growing polypeptide chain. Eventually, this chain folds into a functional protein. Here are the steps at a glance:

• mRNA is synthesized from DNA and travels to ribosome.
• Ribosomes read mRNA codons.
• tRNA brings the correct amino acids.
• Amino acids are linked in order to form a polypeptide chain.
• Polypeptide chain folds into a functional protein.

Through protein synthesis, the genetic code in DNA is ultimately expressed as enzymes, structural proteins, signal receptors, and more, fulfilling myriad biological roles.