Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
12 Cards in this Set
- Front
- Back
What is semi-conservative replication?
|
Produces two copies with an original strand and a newly synthesised strand
|
|
Name 3 difficulties that DNA polymerase has to overcome in replication
|
DNA polymerase cannot separate the 2 DNA strands
Unable to initiate strand, must elongate from primer Strands can only grow in 5' to 3' direction |
|
Describe the role of 3 enzymes in DNA unwinding
|
Helicase - unwinds DNA
Topoisomerase - stops supercoiling Single-strand binding protein - binds to exposed bases |
|
How many times are the leading and lagging strand primed by RNA primer?
|
Leading strand once
Lagging strand every 1000-2000 nucleotides |
|
What are the short fragments on the lagging strand called?
|
Okazaki fragments
|
|
What does primase do?
|
Synthesises RNA primer
|
|
What is the function of exonuclease?
|
Travels 3' to 5' end to proofread DNA
Travels 5' to 3' end for replacing RNA primers with DNA |
|
What is the difference in functions between DNA polymerase III and I?
|
DNA polymerase III - responsible for most DNA synthesis
DNA polymerase I - responsible for replacing RNA primers (Okazaki fragments) with DNA and for proofreading |
|
What seals the lagging strand together?
|
DNA ligase
|
|
What is the function of DNAa?
|
Initiates opening and unwinding of DNA
|
|
Name types of mutagen that may affect DNA replication
|
Radiation
DNA polymerase replication errors Chemicals Oxidative damage |
|
What is a telomere and telomerase?
|
Telomere - end of chromosome that protects it from deterioration
Telomerase - enzyme that carries its own RNA primer to elongate telomere |