gene expression

• DNA is transcribed into RNA by RNA polymerase, which binds to the DNA template strand and synthesizes a complementary RNA molecule.
• DNA Replication: DNA molecule is copied
• DNA and sometimes RNA are the primary sources of heritable information
• DNA and RNA are composed of nucleotides
• Plasmids are circular, double-stranded DNA molecules that provide genes and may aid in the survival of prokaryotic cells
• DNA is synthesized in the 5’ to 3’ direction
• DNA has a negative charge and moves towards the positive or oppositely charged pole
• Replication is a semi-conservative process where the old strand serves as the template for the new strand
• Helicase unwinds the DNA strand by breaking the hydrogen bonds between the nitrogenous base pairs
• Topoisomerase relaxes supercoiling in front of the replication fork
• DNA polymerase 3 requires RNA primers to initiate DNA synthesis
• Primase facilitates the construction of RNA primers
• DNA polymerase synthesizes new strands of DNA continuously on the leading strand and discontinuously on the lagging strand
• DNA polymerase 1 removes the RNA primers and replaces them with nucleotides
• DNA Ligase glues the fragments (Okazaki fragments) on the lagging strand
• DNA Polymerase proofreads newly made DNA and replaces any incorrect nucleotides
• Summarized Process of DNA Replication:

  • Helicase unwinds the parental double helix
  • Molecules of SSBP stabilize the unwounded template strands
  • The leading strand is synthesized continuously in the 5’ to 3’ direction by DNA polymerase 3
  • Primase begins synthesis of the RNA primer for the 5th Okazaki fragment
  • DNA polymerase 3 is completing synthesis
  • DNA polymerase 1 removes the primers and replaces them with nucleotides
  • DNA ligase joins the 3’ end of fragment 2 to the 5’ end of fragment 1