Question

What is the difference between a codon and an anticodon?

Short answer

A codon is a three-nucleotide sequence in mRNA, while an anticodon is a complementary three-nucleotide sequence in tRNA.

Step-by-step solution

Define a Codon

A codon is a sequence of three nucleotides in messenger RNA (mRNA) that specifies a particular amino acid during protein synthesis or signals the termination of translation. It is the basic unit of the genetic code.

Define an Anticodon

An anticodon is a sequence of three nucleotides in transfer RNA (tRNA) that is complementary to a codon in mRNA. It enables the tRNA to bring the correct amino acid to the ribosome during protein synthesis.

Compare Codon and Anticodon

The primary difference between a codon and an anticodon lies in their location and function: codons are located on mRNA and determine the sequence of amino acids in a protein, while anticodons are located on tRNA and ensure that the correct amino acid is added during translation.

Key concepts

Genetic Code

The genetic code is a set of rules that dictate how the nucleotide sequences in DNA and mRNA are translated into proteins. This code is nearly universal for all organisms. It consists of codons, which are sequences of three nucleotides. Each codon specifies a particular amino acid or a stop signal during protein synthesis. For instance, the codon AUG codes for the amino acid methionine and also serves as the start signal for translation. Understanding the genetic code is crucial for grasping how genetic information is expressed as physical traits and biological functions.

mRNA

Messenger RNA (mRNA) is a type of RNA that conveys genetic information from DNA to the ribosome, where proteins are synthesized. mRNA is created during transcription, where an mRNA molecule is produced based on the DNA template. This mRNA strand contains codons, each specifying an amino acid to be added to the growing protein chain. The sequence of codons in mRNA determines the order of amino acids in the resulting protein. mRNA is essential for translating genetic information into functional proteins, enabling the cell to perform various biological activities.

tRNA

Transfer RNA (tRNA) is a small RNA molecule that plays a key role in translating the genetic code into proteins. Each tRNA has an anticodon, a sequence of three nucleotides that is complementary to a specific mRNA codon. The tRNA also carries an amino acid corresponding to its anticodon. During protein synthesis, tRNAs bring the correct amino acids to the ribosome, matching their anticodons with codons on the mRNA strand. This ensures that amino acids are added in the correct sequence, leading to the accurate formation of proteins. Without tRNA, the genetic information in mRNA could not be accurately translated into proteins.

Protein Synthesis

Protein synthesis is the process by which cells produce proteins based on the information in mRNA. It occurs in two main steps: transcription and translation.

During transcription, a segment of DNA is copied into mRNA, which then exits the nucleus and enters the cytoplasm.

In translation, the mRNA strand is read by ribosomes in the cytoplasm. tRNA molecules bring the corresponding amino acids to the ribosome, where they are joined together in the sequence specified by the mRNA codons. This results in the formation of a polypeptide chain, which then folds into a functional protein. Protein synthesis is fundamental for cell function and growth, enabling the production of enzymes, structural proteins, and other essential molecules.

Nucleotides

Nucleotides are the building blocks of nucleic acids like DNA and RNA. Each nucleotide consists of three components: a sugar molecule, a phosphate group, and a nitrogenous base. There are four types of nucleotides in DNA: adenine (A), thymine (T), cytosine (C), and guanine (G). In RNA, thymine is replaced by uracil (U).

These nucleotides pair specifically (A with T or U, and C with G) to form the double-stranded structure of DNA or the single-stranded structure of RNA. Nucleotides play a vital role in encoding genetic information, with sequences of three nucleotides forming codons and anticodons. These sequences are crucial for the accurate translation of genetic information into proteins. Understanding nucleotides is essential for comprehending how genetic information is stored and expressed.