Central Dogma of Molecular Biology

• Replication is the process by which DNA makes identical copies of itself.
• Replication occurs during the S-phase of the cell cycle in preparation for cell division.
• Template: parent DNA strand
• Central dogma of molecular biology consists of replication, transcription, and translation.
• Transcription is RNA synthesis
• Translation is protein synthesis.
• Replication is DNA synthesis
• Transfer of information from cell to cell is by replication.
• Transfer of information from DNA to proteins involves transcription and translation.
• Viruses undergo reverse transcription.
• DNA is replicated in a semi-conservative pattern.
• Initiation is the separation of strands into single strands that would serve as templates.
• Separation of strands begin in the origin of replication.
• Helicase is responsible for unwinding the double stranded DNA by breaking the hydrogen bonds.
• Single strand DNA binding protein (SSBP) is responsible for preventing the separated parental strands from realigning.
• SSBP binds to the single stranded DNA at the replication fork.
• DNA gyrase relaxes the twisting tension of supercoiled twists created in unwinding the parental double helix without rotation.
• Primase serves as primers for elongation of the complementary strand.
• DNA polymerase 3 or DNA replicase catalyzes chain elongation from the 5' to 3' direction with respect to the daughter DNA strand.
• DNA template strand 3'-5' is the leading strand.
• DNA template strand 5'-3' is the lagging strand where formation of Okazaki fragment short chains.
• DNA polymerase 1 proofreads DNA molecule and removes the primers via its exonuclease activity starting from the 3' to 5' direction.
• Replication ends when all the parent DNA nucleotides have been complemented.
• Two daughter molecules are the exact copies of each other and the parent DNA.
• Replication product is two identical daughter DNA.
• Bidirectional - occurs (opening of replication) in two opposite directions about the origin of replication.
• Leading strand has continuous elongation.
• Lagging strand elongation is discontinuous and short chains.
• Transcription is the synthesis of RNA from a DNA template.
• Major enzyme involve in transcription is RNA polymerase.
• Transcription occurs in the G2 phase of interphase.
• Transcription has specific base pairing to copy the DNA.
• The anticoding strand is the only strand of the DNA that is transcribed.
• mRNA is a copy of the coding strand.
• RNA polymerase is a major polymerizing enzyme,
• RNA polymerase attaches to a promoter.
• Pribnow box or TATAAT is a promoter in prokaryotes located at the initiation site where transcription starts.
• Sigma factor recognizes the promoter sequence so the RNA polymerase can selectively bind to it.
• During transcription elongation, RNA polymerase moves along the anticoding while complementing the DNA strand with RNA termination.
• When termination point is reached, rho factor binds with the RNA pol and dissociates it with the DNA strand to stop transcription.