DNA replication Flashcards
What is DNA replication?
DNA replication is the process by which a cell makes an exact copy of its DNA. It occurs during the cell cycle in preparation for cell division.
What do prokaryotic cells include and where does DNA replication occur?
Bacteria and DNA replication occurs in the cytoplasm.
What are the steps of DNA replication?
Initiation, Elongation, Leading strand synthesis, Termination and proofreading and repair.
What is initiation?
DNA replication begins at a specific site on the DNA molecule called the origin of replication.
In prokaryotes, there is usually a single origin of replication. Proteins, such as DnaA, bind to the origin and initiate the unwinding of the DNA double helix, separating the two DNA strands and forming a replication bubble.
What is elongation?
Once the DNA strands are separated, an enzyme called DNA polymerase synthesizes new DNA strands complementary to the template strands.
DNA polymerase adds nucleotides to the growing DNA chain in a 5’ to 3’ direction, extending the new DNA strand one nucleotide at a time.
The two DNA strands are replicated simultaneously in opposite directions from the origin, forming two replication forks that move away from each other.
What is leading strand synthesis?
One of the DNA strands, known as the leading strand, is synthesized continuously in the 5’ to 3’ direction as the replication fork advances. DNA polymerase synthesizes the leading strand continuously by adding nucleotides to the growing end of the new DNA strand, using the template strand as a guide.
What is lagging strand synthesis?
The other DNA strand, known as the lagging strand, is synthesized discontinuously in short fragments called Okazaki fragments.
DNA polymerase synthesizes each Okazaki fragment in the 5’ to 3’ direction away from the replication fork, creating short segments of DNA that are later joined together by another enzyme called DNA ligase.
What is Termination?
DNA replication continues bidirectionally until the replication forks meet and the entire DNA molecule is replicated.
At this point, replication terminates, and the two newly synthesized DNA molecules separate from each other.
What is proofreading and repair?
Throughout the DNA replication process, DNA polymerase also has a proofreading function that helps to correct any errors in the newly synthesized DNA strands.
Additionally, other enzymes repair any damaged or mismatched nucleotides to ensure the fidelity of the replicated DNA.
DNA replication in prokaryotes in a whole?
Is a highly coordinated and efficient process that ensures the accurate duplication of genetic material to be passed on to daughter cells during cell division.
what experimental evidence/techniques can be used to elucidate the process of DNA replication with a prokaryote ?
Electron Microscopy
What is electron microscopy?
Electron microscopy can be used to directly visualize and analyze the ultrastructure of replicating DNA molecules in prokaryotic cells.
This technique provides high-resolution images of DNA replication intermediates, replication forks, and other structures associated with DNA replication, allowing researchers to study the details of DNA replication in vivo.
What is a prokaryote?
Prokaryotes are organisms whose cells lack a nucleus and other organelles.
What are the two distinct groups in a prokaryote?
Bacteria and Archea.
What is a eukaryotic cell?
Eukaryotic cells are cells containing membrane-bound organelles and are the basis for both unicellular and multicellular organisms.
