Question

What is the anticodon on tRNA for each of the following codons in mRNA? a. GUG b. CCC c. GAA

Short answer

a. CAC b. GGG c. CUU

Step-by-step solution

Understand the Genetic Code

The genetic code consists of triplets of nucleotides called codons, which specify particular amino acids. Each codon on mRNA is complementary to an anticodon on tRNA.

Identify mRNA Codons

The given mRNA codons are: a. GUGb. CCCc. GAA

Find Complementary Anticodon Sequences for tRNA

Determine the anticodons for each mRNA codon by pairing the nucleotides following the base pairing rules (A with U, and G with C):a. GUG (mRNA) -> CAC (tRNA)b. CCC (mRNA) -> GGG (tRNA)c. GAA (mRNA) -> CUU (tRNA)

Key concepts

genetic code

The genetic code is like a dictionary that translates the language of nucleic acids into the language of proteins. It consists of sequences of three nucleotides in DNA or RNA, known as codons. Each codon corresponds to a specific amino acid or a stop signal during protein synthesis. The genetic code is nearly universal, meaning it is the same across most organisms. This code is crucial because it ensures that the right proteins are made according to the genetic instructions within the cell. The 'dictionary' has 64 entries (combinations of four nucleotides; adenine (A), uracil (U), guanine (G), and cytosine (C)) that map to 20 amino acids and stop signals.

mRNA codons

Messenger RNA (mRNA) carries the genetic instructions from DNA to the ribosome, where proteins are made. During transcription, DNA is copied into mRNA. This mRNA contains codons, which are groups of three nucleotides. For instance, in our exercise, the mRNA codons are GUG, CCC, and GAA. Each codon specifies a particular amino acid. The ribosome reads these codons during the process called translation, ensuring that each amino acid gets added in the correct order to form a protein. It's like reading a recipe, where each codon is an instruction for adding an ingredient.

base pairing rules

The base pairing rules describe how nucleotides form pairs in a DNA or RNA strand. In RNA, the rules are: adenine (A) pairs with uracil (U), and guanine (G) pairs with cytosine (C). These rules are essential during transcription when mRNA is created from a DNA template and during translation when tRNA matches its anticodon with the mRNA codon. For example, in our exercise, for the mRNA codon GUG, the correct tRNA anticodon would be CAC (because G pairs with C, U pairs with A, and G pairs with C). These rules ensure that the genetic information is accurately translated into proteins.

tRNA anticodons

Transfer RNA (tRNA) acts as a bridge between the mRNA codons and the amino acids they code for. Each tRNA molecule has an anticodon, a set of three nucleotides that can base-pair with a specific mRNA codon. For example, in our exercise, the tRNA anticodon for the mRNA codon GUG is CAC. When mRNA codons are read by the ribosome, tRNA brings the appropriate amino acid to the growing protein chain. The anticodon on tRNA ensures that each codon in the mRNA is paired with the correct amino acid, facilitating the accurate translation of genetic information into functional proteins. This precise match is critical for making sure proteins are synthesized correctly.