1. Transcription: From DNA to RNA
* Location: Nucleus of the cell
* Process: The gene's DNA sequence is copied into a messenger RNA (mRNA) molecule.
* DNA unwinds: The double helix of DNA separates, exposing the gene sequence.
* RNA polymerase binds: An enzyme called RNA polymerase attaches to the DNA and reads the gene sequence.
* RNA synthesis: RNA polymerase builds a complementary mRNA molecule, using the DNA sequence as a template.
* Termination: The RNA polymerase detaches, and the mRNA molecule is released.
2. Translation: From mRNA to Protein
* Location: Cytoplasm of the cell, specifically at ribosomes
* Process: The mRNA molecule carries the genetic code to the ribosomes, where it's used to build a protein.
* Ribosome binds: The mRNA molecule binds to a ribosome.
* Codons: The mRNA sequence is read in groups of three nucleotides called codons. Each codon corresponds to a specific amino acid.
* tRNA brings amino acids: Transfer RNA (tRNA) molecules, each carrying a specific amino acid, bind to the mRNA codons according to their complementary anticodon.
* Peptide bond formation: The ribosome joins the amino acids together, forming a chain called a polypeptide.
* Termination: The ribosome reaches a stop codon on the mRNA, signaling the end of translation. The polypeptide chain is released and folds into a functional protein.
Key Players:
* DNA: The blueprint for protein synthesis.
* mRNA: Messenger RNA, a copy of the gene sequence.
* Ribosome: The site of protein synthesis.
* tRNA: Transfer RNA, which carries amino acids to the ribosome.
* RNA polymerase: An enzyme that transcribes DNA into RNA.
* Amino acids: The building blocks of proteins.
* Codons: Three-nucleotide sequences on mRNA that specify amino acids.
In Summary:
Gene expression involves two main steps: transcription and translation. DNA is transcribed into mRNA, which is then translated into a protein. This process allows cells to produce specific proteins based on the genetic information encoded in their DNA.
