DNA replication Flashcards
Cell division takes place in which two main stages?
- Nuclear division: The process by which the nucleus divides. Two types of nuclear division: mitosis and meiosis.
- Cytokinesis: Follows nuclear division and is the process by which the whole cell divides.
What must occur before nuclear division?
DNA replication.
Which is the current model of DNA replication and what does this mean?
Semi-conservative replication which means that half the strands of DNA in the new DNA molecule are from the original. This means there is genetic continuity between generations of cells?
What does genetic continuity between generations of cells mean?
The cells produced by cell division inherit their genes from their parent cells).
What are the 4 requirements for semi-conservative replication to take place?
- The 4 types of nucleotide, each with their base of ATCG, must be present.
- Both strands of the DNA molecule act as a template for the attachment of nucleotides.
- DNA polymerase
- A source of chemical energy is required to drive the process.
What is the job of DNA helicase?
It breaks the bond between bases on the two polynucleotide DNA strands. This makes the helix unwind to form two single strands.
What happens after the unwinding of the two polynucleotides occurs?
Each original single strand acts as a template for a new strand. Complementary base pairing means that free-floating DNA nucleotides are attracted to their complementary exposed bases on each original template strand.
What is the role of DNA polymerase in DNA replication?
It catalyses the condensation reactions that joins the new strands together. Hydrogen bonds form between the bases on the original and new strands.
Brief summary of the work by Meselson and Stahl.
They provided evidence for semi-conservative replication by using two isotopes of nitrogen.
