DNA replication Flashcards
When does DNA replication occur in the cell cycle, why does DNA replication occur at this specific stage?
- Before cell division (mitosis/ meiosis.) During interphase.
- DNA must replicate to provide a copy of DNA for the new cell that is created by cell division.
What is the method of DNA replication called? What does the daughter DNA from this method of replication compose of?
- “Semi- conservative replication.”
- In the daughter DNA (ie. replicated DNA), one strand is from parental DNA (ie. original copy of DNA) and the other strand is newly synthesised.
() - extra info for clarification.
Why is semi- conservative replication of DNA important?
- Ensures genetic continuity between generations of cells (as all of the daughter DNA will have original copy of the initial DNA.)
() - extra info for clarification.
Why is complementary base pairing important in DNA replication?
- Enables identical copies of DNA to be created.
- Helps to reduce copying errors (which would result in mutations.)
Give the 2 key enzymes that are involved in semi- conservative DNA replication.
1.) DNA helicase
2.) DNA polymerase.
What is meant by term “parental DNA?”
- Name given to the original DNA that is going to be copied.
What is step 1 of semi- conservative DNA replication?
- DNA helicase breaks hydrogen bonds between the complementary base pairs between the two polynucleotide strands within the double helix.
- This causes the DNA double helix to unwind/ the two strands separate from each other.
Step 2 of semi- conservative DNA replication.
- Each of separated parental DNA strands act as a template (for other nucletodies. )
- Free- floating nucleotides - within nucleus- are attracted to their complementary exposed base pairs on the template strands’ (nucleotides) of the parental DNA (POINT: the nucleotide is just NEXT to its complementary base pair, not actually bonded to each other at this point.)
() - extra info for clarification.
Step 3 of semi- conservative DNA replication.
- The adjacent nucleotides (one on parental strand/ one on synthesised strand) are joined together to form a phosphodiester bond by a condensation reaction.
- DNA polymerase catalyses the joining together of adjacent nucleotides.
What are the 2 sets of daughter DNA (produced from semi- conservative replication) comprised of?
- Contains one strand of parental/ original DNA.
- Contains one newly synthesised strand of DNA.
Function of DNA helicase.
- Unwinds double helix DNA and breaks hydrogen bonds between the two polynucleotide strands.
Function of DNA polymerase.
- DNA polymerase catalyses the condensation reaction that joins together adjacent nucleotides.
