What is an anticodon?
Anticodons are sequences of nucleotides that complement the codon. They are found in tRNA and allow tRNAs to produce the correct amino acids corresponding to mRNA during protein production.
During protein production, amino acids are bound together in a string, such as beads on a necklace. The right amino acid must be used in the right places because amino acids have different properties. Putting the wrong one in place can make a protein useless, or be dangerous to the cell.
This graphic shows an increasing protein chain. At the bottom left, you can see tRNAs entering the ribosome complex carrying amino acids. If all goes well, the tRNA with only the right anticodon will successfully bind to the exposed mRNA, so only the correct amino acid will be added:
The tRNAs are responsible for incorporating the correct amino acids into the protein according to mRNA instructions. Their anticodons, which pair-bond with the codon on the mRNA, allow them to perform this task.
Function of Anticodons
The function of Anticodons is to bring together the right amino acids to form proteins based on the instructions in the mRNA.
Each tRNA contains one amino acid and one anticodon. When the anticodon successfully binds to the mRNA codon, the cellular machinery realizes that the correct amino acid has to be added to the growing protein.
Anticodons are necessary to carry out the process of transforming the information stored in DNA into functional proteins that a cell can use to carry out its life functions.
How Anticodons Work?
When genetic information has to be converted into proteins, the sequence of events is as follows:
- Genetic information in the cell’s genome is transferred to mobile fragments of RNA using base-pairing rules. Each nucleotide has only one other nucleotide that binds to it.
- By tying the correct RNA nucleotides with each DNA nucleotide, the RNA polymerase forms an edge of RNA that contains all the correct information to form a protein.
- This “messenger RNA,” or “mRNA”, then travels to the ribosome, the site of protein production.
- In ribosomes, the rules of base-pairing are again used to ensure the correct transfer of information. Each three-nucleotide “codon” in the mRNA is mated to an “anticodon” that has complementary bases.
- “Transfer RNAs” or “tRNAs” that string proteins together, each containing an anticodon that matches an mRNA codon, and an amino acid attached.
- When the correct tRNA finds mRNA, its amino acids are added to the growing protein chain.
- Enzymes catalyze the binding of amino acids together as tRNA anticodons bind to the correct mRNA codon.
- When the amino acid of the tRNA has been added to the protein chain, the tRNA is released to take the new amino acid to bring in new amino acid.
- Interestingly, this means that tRNA is the RNA variant of the nucleotide sequence, similar to the original gene in anticodon.
- Remember – genes were transferred using complementary nucleotides to form RNA, which subsequently had to bind to complementary tRNA codes.
RNA Base Pairing Rules
Each RNA nucleotide can only hydrogen bond to each other nucleotide. It is by linking together the correct nucleotides that DNA and RNA successfully transfer and use information.
The four bases of RNA are adenine, cytosine, guanine, and uracil. These bases are often referred to by their first letter, making it easier to show sequences of multiple bases. The base-pairing rules for RNA are:
- A – u
- C – G
- G C
- U – A
Put more simply in RNA, nucleotides always bind with U nucleotides, and C nucleotides always bind with G nucleotides.
Differences Between RNA and DNA
Note that in DNA, the “uracil” base is a different base called “thymine”. In DNA, A, and T pair. RNA adenine will also pair with DNA’s thymine, and DNA adenine will pair with RNA’s uracil.
The difference between uracil and thymine is that thymine has an additional methyl group, which makes it more stable than uracil.
It is thought that DNA uses Thymine instead of Uracil because, as the cell’s “master blueprint”, the information stored in the DNA must remain stable for a long time. RNAs are simply copies of DNA made for specific purposes and are used by the cell for a short time before being used.
What is an anticodon? Function, RNA Base Pairing