For each of these statements about the genetic code, select True or False.
a. T/F Wobble pairing accounts for the redundancy of the genetic code.
b. T/F There are 64 different tRNAs that read the 64 possible codons.
c. T/F All possible codons are used, but not all codons specify an amino acid.
d. T/F Some codons are recognized by proteins, not by tRNAs.

Verified step by step guidance

1. Understand the concept of wobble pairing: Wobble pairing refers to the flexibility in base-pairing rules at the third position of a codon, allowing some tRNAs to recognize multiple codons. This contributes to the redundancy of the genetic code, where multiple codons can code for the same amino acid.
2. Analyze the statement about the number of tRNAs: There are 64 possible codons (4 bases^3 positions), but not all codons require a unique tRNA. Due to wobble pairing, fewer than 64 tRNAs are needed to read all codons.
3. Evaluate the statement about codon usage: All 64 codons are used in the genetic code, but not all codons specify an amino acid. For example, stop codons (e.g., UAA, UAG, UGA) signal the termination of translation and do not code for amino acids.
4. Examine the statement about codons recognized by proteins: Some codons, such as stop codons, are not recognized by tRNAs but are instead recognized by release factors, which are proteins that terminate translation.
5. For each statement, apply the relevant biological concept to determine whether it is true or false based on the explanations provided in the previous steps.

Key Concepts

Wobble Pairing

Wobble pairing refers to the flexibility in base pairing between the third base of a codon and the corresponding anticodon of tRNA. This phenomenon allows a single tRNA to recognize multiple codons that code for the same amino acid, contributing to the redundancy of the genetic code. This flexibility helps to minimize the impact of mutations and ensures efficient protein synthesis.

tRNA and Codons

Transfer RNA (tRNA) molecules are responsible for bringing amino acids to the ribosome during protein synthesis, matching their anticodons to the corresponding codons on the mRNA. While there are 64 possible codons (combinations of three nucleotides), there are fewer than 64 distinct tRNAs due to the wobble effect, which allows some tRNAs to pair with multiple codons. This means that not every codon has a unique tRNA.

Codon Usage

Codon usage refers to the frequency with which different codons are used to encode amino acids in a given organism. While all 64 codons exist, not all are utilized in every organism, and some codons may not specify an amino acid at all, serving instead as stop signals. Additionally, certain codons may be recognized by proteins or other molecules, highlighting the complexity of genetic translation beyond just tRNA recognition.