Proteins are made through a biological process called protein synthesis, which involves two main stages: transcription and translation. The instructions for making proteins are encoded in the DNA of cells. During transcription, a section of DNA is copied into messenger RNA (mRNA). Then during translation, the ribosome reads the mRNA sequence and assembles the protein by linking amino acids together in the specific order dictated by the mRNA. Amino acids are the building blocks of proteins, and the sequence of these amino acids determines the protein's unique structure and function.
How Proteins Are Made:
- The DNA sequence of a gene contains the instructions for the amino acid sequence of the protein.
- In the nucleus, the gene's DNA sequence is transcribed into mRNA.
- The mRNA leaves the nucleus and attaches to a ribosome in the cytoplasm.
- The ribosome reads the mRNA codons (sets of three nucleotides).
- Transfer RNA (tRNA) molecules bring specific amino acids matching the codons.
- Amino acids are linked together in a chain to form the protein.
- The chain folds into a unique 3D structure that defines the protein's properties and functions.
What Proteins Are Made Of:
- Proteins are polymers made of long chains of amino acids linked by peptide bonds.
- There are 20 standard amino acids commonly used in proteins.
- The sequence of amino acids is dictated by the gene's nucleotide sequence.
- Protein folding and modifications after synthesis give proteins their functional shapes.
In summary, the genetic code in DNA "makes" proteins by specifying the order of amino acids, which cells then assemble into proteins through transcription and translation processes inside the cell.
