DNA replication is the process of creating an identical copy of a DNA molecule. This happens in the nucleus of a cell and follows these steps:
1. Unwinding: The DNA double helix unwinds, separating the two strands. This is done by an enzyme called helicase.
2. Priming: A short RNA sequence called a primer is attached to each strand, acting as a starting point for DNA synthesis.
3. Elongation: An enzyme called DNA polymerase binds to the primer and begins to add complementary nucleotides to the original strand, building a new strand. This happens in a 5' to 3' direction.
4. Proofreading: DNA polymerase has a built-in proofreading mechanism, which checks for errors and corrects them.
5. Termination: Once the entire strand is copied, the process ends, resulting in two identical DNA molecules.
Transcription is the process of converting the genetic information stored in DNA into a messenger RNA (mRNA) molecule. This occurs in the nucleus and follows these steps:
1. Unwinding: A section of DNA containing the gene of interest unwinds, exposing the bases.
2. Initiation: The enzyme RNA polymerase binds to a specific DNA sequence called the promoter, which signals the start of a gene.
3. Elongation: RNA polymerase moves along the DNA strand, using one strand as a template to build a complementary mRNA strand. This process also happens in the 5' to 3' direction. Instead of thymine (T) in DNA, uracil (U) is used in mRNA.
4. Termination: RNA polymerase reaches a specific DNA sequence called the terminator, signaling the end of the gene. The mRNA molecule detaches from the DNA.
DNA replication is a process of copying the entire genome to create two identical DNA molecules. Transcription is a process of copying a specific gene from DNA to mRNA. The mRNA then travels out of the nucleus to the cytoplasm, where it is used as a template to build proteins in a process called translation.
