1. Transcription:
* DNA to RNA: The genetic information encoded in DNA is copied into a messenger RNA (mRNA) molecule.
* This process occurs in the nucleus of eukaryotic cells and the cytoplasm of prokaryotic cells.
* The DNA sequence is read by an enzyme called RNA polymerase, which creates a complementary mRNA molecule.
2. Translation:
* RNA to protein: The mRNA molecule travels to the ribosomes, where it is translated into a protein sequence.
* Ribosomes read the mRNA codons (three-nucleotide sequences) and use transfer RNA (tRNA) molecules to bring the corresponding amino acids to the ribosome.
* These amino acids are then linked together in a chain, forming a polypeptide, which folds into a functional protein.
Here's a more detailed breakdown of the pattern:
Transcription:
* Initiation: RNA polymerase binds to a specific region of DNA called the promoter, initiating transcription.
* Elongation: RNA polymerase moves along the DNA template strand, reading the DNA sequence and creating a complementary mRNA molecule.
* Termination: When RNA polymerase encounters a termination sequence, transcription ends, releasing the mRNA molecule.
Translation:
* Initiation: The mRNA molecule binds to the ribosome, and the first tRNA molecule carrying methionine (the start codon) binds to the ribosome.
* Elongation: The ribosome moves along the mRNA molecule, reading each codon and recruiting the corresponding tRNA molecules carrying their respective amino acids. Amino acids are added to the growing polypeptide chain.
* Termination: When the ribosome reaches a stop codon, translation ends, releasing the newly synthesized polypeptide.
Overall, the pattern of protein synthesis is essentially a sequence of copying and reading:
* DNA is copied into mRNA (transcription).
* mRNA is read to create a protein (translation).
This pattern ensures that the genetic information encoded in DNA is accurately expressed as functional proteins, which carry out various cellular functions.
