Cells make proteins through a process called protein synthesis. This process involves two main steps: transcription and translation.
During transcription, the DNA in the cell's nucleus is first unwound and copied into a messenger RNA (mRNA) molecule. This process is carried out by an enzyme called RNA polymerase. The mRNA molecule carries the genetic instructions for making a specific protein.
After transcription, the mRNA molecule moves out of the nucleus and into the cytoplasm, where translation occurs. During translation, the mRNA molecule binds to a ribosome, which acts as a molecular machine that assembles the protein. The ribosome reads the genetic code in the mRNA and uses it to string together amino acids in the correct order to make the protein.
Transfer RNA (tRNA) molecules bring the individual amino acids to the ribosome. Each tRNA molecule carries a specific amino acid and has a sequence of three nucleotides called an anticodon that is complementary to the codon on the mRNA. This ensures that the correct amino acid is added to the growing protein chain.
As the ribosome moves along the mRNA molecule, it reads each codon and brings in the corresponding amino acid, linking them together to form a protein chain. The process continues until a stop codon is reached, signaling the end of protein synthesis.
After synthesis, the newly formed protein may undergo further modifications, such as folding or addition of chemical groups, to become fully functional. It may also be targeting to specific cellular locations or transported out of the cell for use elsewhere in the body.
How cells make proteins quick check
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