Problem 7 - Biology: Concepts and Applications

Question

Anticodons pair with _____. a. mRNA codons b. DNA codons c. RNA anticodons d. amino acids

Step-by-Step Solution

Answer

Anticodons pair with mRNA codons, answer a.

Step 1: Understanding Anticodons

Anticodons are a sequence of three nucleotides found in tRNA molecules. Their role is to identify the mRNA codon during protein synthesis and ensure the correct amino acid is added to the growing polypeptide chain.

Step 2: Understanding mRNA Codons

mRNA codons are a sequence of three nucleotides in the mRNA that specify which amino acid will be added next during protein synthesis. Each codon corresponds to a specific amino acid or a stop signal in protein synthesis.

Step 3: Matching Anticodons with the Correct Pair

Anticodons in tRNA molecules bind specifically with complementary codons on mRNA during protein synthesis. This ensures the right amino acid is incorporated into the protein chain. Therefore, anticodons pair with mRNA codons.

Step 4: Choosing the Correct Answer

Since anticodons bind with mRNA codons, the correct answer to the given multiple choice question is option a: mRNA codons.

Key Concepts

tRNA

Transfer RNA, or tRNA, is a crucial molecule in the process of protein synthesis. This process takes place in the ribosome of a cell. The primary role of tRNA is to serve as an adaptor that translates the genetic code in the mRNA into a specific sequence of amino acids.

Each tRNA molecule has a specific region called an "anticodon". An anticodon is made up of three nucleotides. These nucleotides pair with a complementary three-nucleotide sequence called a codon on the messenger RNA (mRNA).

• The anticodon-codon pairing ensures the correct amino acid is delivered to the ribosome.
• The tRNA has an amino acid attachment site that links to a specific amino acid corresponding to its anticodon sequence.

By doing this, tRNA effectively translates the genetic instructions stored in mRNA into a chain of amino acids. This chain will then fold and form proteins, which perform countless functions in the cell.

mRNA codons

Messenger RNA (mRNA) is crucial as it acts as the template for protein synthesis. During transcription, a portion of the DNA is copied into mRNA. The mRNA carries this genetic information from the DNA in the nucleus to a ribosome, where proteins are made.

• mRNA codons are sequences of three nucleotides each.
• Each codon specifies a particular amino acid or a stop signal for the termination of protein synthesis.

For example, the mRNA codon sequence "AUG" is known as the start codon. It not only signals the beginning of protein synthesis but also codes for the amino acid methionine.
This specificity is crucial for the production of proteins in a precise sequence, which determines how proteins function within the cell.

Protein Synthesis

Protein synthesis is a vital cellular process that converts genetic information into functional proteins. It consists of two main stages: transcription and translation.

1. Transcription

During transcription, the DNA sequence of a gene is transcribed into mRNA. This process occurs in the nucleus.

• RNA polymerase, an enzyme, binds to the DNA and assembles the mRNA chain using DNA as a template.

2. Translation

Translation is the next step, where the mRNA migrates to the ribosome in the cytoplasm. Here, the ribosome reads the mRNA codons. Each codon specifies an amino acid, and tRNA molecules bring the corresponding amino acids.

• The anticodons on tRNA pair with the codons on mRNA, ensuring the correct sequence of amino acids.

Ultimately, this results in a long chain of amino acids that will fold into a functional protein.

Amino Acids

Amino acids are the building blocks of proteins. Proteins are essential macromolecules that play numerous roles in cells, from catalyzing reactions as enzymes to providing structural support.

• There are 20 different amino acids that combine in various ways to form proteins.
• Each amino acid has a specific side chain, which can affect the protein's properties and function.

In protein synthesis, amino acids are added one by one to a growing polypeptide chain. The sequence of the mRNA codons determines the order in which amino acids are added.
This sequence is critical because it dictates the protein's three-dimensional structure and, consequently, its function. A single change in the sequence can alter a protein's function and potentially lead to significant biological consequences.