DNA REPLICATION Flashcards
DNA REPLICATION IS SEMI-…………………………….
CONSERVATIVE
DNA REPLICATION OCCURS IN A ……..’ TO ……..’ DIRECTION BY FORMATION OF ………………………………….. BONDS
5
3
PHOSPHODIESTER
INCOMING ………….. UNDERGOES ……………….. ATTACK BY THE …….’ OH ON THE P OF dNTP.
dNTP
NUCLEOPHILIC
3
TO REGULATE REPLICATION, A …………………………… IS FORMED.
REPLISOME
WHY ARE THE LEADING AND LAGGING STRAND SYNTHESISED DIFFERENTLY
- DNA IS ANTIPARALLEL
2. DNA POLYMERASE CAN ONLY MOVE IN THE 5’ TO 3’ DIRECTION
WHAT DOES LAGGING STRAND SYNTHESIS REQUIRE
- DNA PRIMASE (RNA PRIMER)
- DNA POLYMERASE
- RIBONUCLEASE H
- DNA LIGASE
WHAT IS USED TO SEPARATE PAIRED DNA
DNA HELICASE BY USE OF ATP
WHAT ISSUES CAN MUTATIONS IN DNA HELICASES GIVE RISE TO
WERNERS SYNDROME (A PROGERIA) CAUSED BY AUTOSOMAL RECESSIVE REC1 HELICASE GENE WRN
GIVE ANOTHER EXAMPLE OF A CONDITION CAUSED BY A HELICASE MUTATION
BLOOM SYNDROME (CANCER) LOF IN RECQ FAMILY WHICH MAINTAINS GENOME INTEGRITY
WHAT IS PROCESSIVITY
ENZYME ABILITY TO CATALYSE CONSECUTIVE REACTIONS WITHOUT RELEASING IT SUBSTRATE
WHAT ENHANCES PROCESSIVITY OF DNA POLYMERASES
- SLIDING CLAMP
- SINGLE STRANDED DNA BINDING PROTEINS
- DNA TOPOISOMERASES
WHAT DOES THE SLIDING CLAMP DO
- FORMS A COMPLEX WITH A CLAMP LOADER VIA ATP
2. THIS COMPLEX BINDS TO DNA AND DNA POLYMERASE NEAR THE PRIMER
WHAT DO SINGLE STRANDED DNA BINDING PROTEINS DO
- SSB EXPOSE THE SINGLE STRAND IN THE REPLICATION FORK
- PREVENTS THE STANDS BINDING TO ITSELF MAKING BASE PAIRED HAIR PIN
- PREVENTS REPLICATION FORK STALLING
WHAT DO TOPOISOMERASES DO
- RELAX SUPERHELICAL TENSION CAUSED BY THE UNWINDING OF DNA
2. PREVENTS TANGLING
WHAT DOES TOPOISOMERASE 1 DO
NICKS AND RESEALS ONE OF TWO DNA STRANDS, NO ATP
