From DNA to Proteins: A Simple Guide

How do your cells make proteins? They follow instructions stored in DNA, building the proteins your body needs for growth, repair, and daily life.

Think of DNA as an instruction book. A gene is a section of DNA that contains instructions for making a particular protein chain.

Proteins are made from smaller units called amino acids. Their order matters because it helps determine how the protein folds and what it does.

Protein synthesis has two main stages: transcription and translation. First, a gene's instructions are copied into RNA, then used to build an amino acid chain.

During transcription, DNA opens at the gene inside the nucleus. One strand acts as a template for making messenger RNA, using complementary base pairing.

RNA uses the base uracil instead of thymine, so A pairs with U. The messenger RNA, or mRNA, leaves the nucleus through a pore.

Next, mRNA attaches to a ribosome in the cytoplasm. Translation begins here, as the ribosome reads the message to build a chain of amino acids.

The ribosome reads three mRNA bases at a time. Each group is called a codon, which specifies an amino acid or gives a stop signal.

Transfer RNA, or tRNA, brings amino acids to the ribosome. Each tRNA carries an anticodon, a three-base sequence that pairs with a matching mRNA codon.

For example, the mRNA codon AUG pairs with the tRNA anticodon UAC. AUG usually marks the start of translation and codes for the amino acid methionine.

The ribosome joins neighbouring amino acids with peptide bonds. As it moves along mRNA, more amino acids join, making a longer chain called a polypeptide.

Translation ends when the ribosome reaches a stop codon. No amino acid is added there, and the finished chain is released from the ribosome.

The chain folds into a shape that helps it work. Remember, transcription copies DNA instructions into mRNA, while translation uses those instructions to assemble amino acids.