Replication Fork Flashcards
(15 cards)
In which direction is DNA synthesized?
5’ to 3’
In which direction is the template strand of DNA read?
3’ to 5’
What are used as substrates during DNA synthesis?
Deoxyribonucleoside triphosphates (dNTPs)
What enzyme catalyzes the synthesis of DNA?
DNA polymerase
What is meant by DNA replication being semi-conservative?
The new dsDNA consists of 1 strand of template DNA from the parent and 1 strand of newly synthesized DNA.
Why are mistakes during DNA replication more severe than those in transcription?
Mistakes in DNA replication can become permanent.
How do DNA and RNA polymerases differ in terms of accuracy?
DNA: one mistake every 10^7 nucleotides
RNA: one mistake every 10^4 nucleotides
How do DNA and RNA polymerases differ in terms of primers?
Primers are required for DNA synthesis. Nucleotides cannot be added to an empty template.
Primers are not required for RNA.
What are primers?
Short DNA or RNA oligonucleotides which base-pair with template to allow DNA polymerase to start synthesis.
Why is replication so complex?
Two DNA polymerases synthesize two DNA molecules using a doublle-stranded, anti-parallel template, and this must occur at the same time.
What is the origin of replication?
Predefined location on the chromosome where replication begins.
What is the replication fork?
dsDNA is opened up at ORI, forming a replication bubble with 2 replication forks.
What happens as soon as the DNA is opened?
RNA primers are added and DNA synthesis begins.
Differentiate between the leading and lagging strands of the DNA forks.
Leading strand has continuous DNA synthesis. Lagging strand has discontinuous DNA synthesis.
What is meant by replication being bi-directional?
Two replication forks replicate in opposite directions.
