To understand how DNA codes for specific proteins within a cell, it's crucial to know the process of protein synthesis. DNA holds the genetic information in its sequence of nucleotides. This information is transcribed into messenger RNA (mRNA) in a process called transcription. During transcription, RNA polymerase enzyme binds to the DNA and reads the sequence of nitrogen bases (adenine, thymine, cytosine, and guanine).
The RNA polymerase then creates a complementary mRNA strand by matching RNA nucleotides (adenine, uracil, cytosine, and guanine) to the DNA template. The sequence of nitrogen bases in the mRNA corresponds to the sequence of bases in the DNA, with uracil replacing thymine.
The mRNA strand carries this genetic information from the nucleus to the ribosomes in the cytoplasm. At the ribosomes, the mRNA is translated into a specific protein through a process called translation. During translation, transfer RNA (tRNA) molecules bring amino acids to the ribosome based on the codons (three-base sequences) on the mRNA.
Each codon codes for a specific amino acid. The ribosome reads these codons and assembles the amino acids brought by tRNA into a polypeptide chain, which then folds into a functional protein. Therefore, the order of nitrogen bases in the mRNA, determined by the DNA sequence, ultimately dictates the sequence of amino acids in a protein, allowing DNA to code for specific proteins within a cell.
