1. Transcription:
* DNA is used as a template to create a messenger RNA (mRNA) molecule. This occurs in the nucleus of the cell.
* RNA polymerase is an enzyme that binds to the DNA at a specific region called the promoter.
* RNA polymerase unwinds the DNA and reads the sequence of bases (A, T, C, G) along one strand, using it as a template to build a complementary mRNA molecule.
* The mRNA molecule is a single-stranded copy of the DNA sequence, but with uracil (U) replacing thymine (T).
2. Translation:
* mRNA travels out of the nucleus and into the cytoplasm, where it encounters ribosomes. Ribosomes are complex structures made of ribosomal RNA (rRNA) and proteins.
* The ribosome reads the mRNA sequence in codons, groups of three nucleotides. Each codon specifies a particular amino acid.
* Transfer RNA (tRNA) molecules carry specific amino acids to the ribosome. Each tRNA has an anticodon that matches a specific codon on the mRNA.
* The ribosome links the amino acids together in the order specified by the mRNA, forming a polypeptide chain.
* The polypeptide chain folds into a specific three-dimensional structure, becoming a functional protein.
Here's a simplified analogy:
Imagine DNA is a recipe book with instructions for making different proteins. Transcription is like copying a recipe from the book onto a notecard (mRNA). Translation is like using the notecard to gather ingredients (amino acids) and follow the instructions to build a specific dish (protein).
Key points:
* The genetic code is universal, meaning that the same codons specify the same amino acids in all living organisms.
* Gene expression is regulated, meaning that cells can control which genes are transcribed and translated at any given time.
* Mutations in DNA can lead to changes in the protein sequence, which can alter the protein's function.
Let me know if you have any further questions.
