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
WHAT DOES TOPOISOMERASE 2 DO
NICKS AND RESEALS BOTH STRANDS OF DNA USING ATP
WHAT IS AN ORIGIN OF REPLICATION
SPECIFIC DNA SEQUENCES THAT RECRUIT REPLICATION INITIATOR PROTEINS
HOW MANY REPLICATION ORIGINS ARE IN YEAST
600-700
HOW MANY REPLICATION ORIGINS ARE IN E COLI
1
HOW MANY REPLICATION ORIGINS ARE IN HUMANS
100,000+
REPLICATION ORIGINS IN YEAST ARE
AUTONOMOUSLY REPLICATING SEQUENCES
REPLICATION ORIGINS IN HUMANS ARE
POORLY UNDERSTOOD
SEQUENCES NEAR LMNB2, MYC
DEFINE BY CHROMATIN STRUCTURE
WHAT ARE THE PHASES OF REPLICATION INITIATION IN EUKARYOTES
- REPLICATOR SELECTION OCCURS IN G1 -
FORMATION OF PRE- C COMPLEX - ORIGIN ACTIVATION OCCURS IN S PHASE
WHAT HAPPENS IN FORMING PRE C COMPLEX
- ORIGIN RECOGNITION COMPLEX BINDS TO REPLICATOR SEQUENCE
- HELICASE LOADING PROTEINS CDC6 AND CDT1 BIND TO ORC
- HELICASE MCM2-7 BINDS TO COMPLETE FORMATINO OF PRE C
WHAT HAPPENS IN ORIGIN ACTIVATION
- UNWINDING OF DNA AND RECRUITMENT OF DNA POLYMERASE
2. HIGH LEVELS OF CDK ACTIVITY IN S PHASE ACTIVATES EXISTING PRE RC BUT PREVENTS FORMATION OF NEW PRE RC
AT THE END OF REPLICATION RNA PRIMER IS REMOVED BY ………………………….
RIBONUCLEASE H
RNA PRIMER REMOVAL SHORTENS THE DNA STRAND AT THE …….’ END WHERE ……………… HAS BEEN REMOVED LEAVING A ……….’ OVERHANG
5
RNA PRIMER
3
WHAT RIBONUCLEOPROTEIN PREVENTS THE SHORTENING OF THE CHROMOSOME AT THE END OF REPLICATION DUE TO THIS ISSUE
TELOMERASE
WHAT IS THE ROLE OF TELOMERASE
ADDS TTAGGG REPEATS TO COMPENSATE FOR THE LOSS OF SEQUENCES EXTENDING THE 3’ FRAGMENT. TO PROTECT CHROMOSOMAL INTEGRITY
WHAT IS TELOMERASE
A RIBONUCLEOPROTEIN WITH AN RNA COMPENENT FOR TELOMERE REPEATS TO BE SYNETHESISED
WHAT IS THE STEPWISE PROCESS OF TELOMERASE
TELOMERASE SHUFFLE DONE STEP WISE 6 NUCLEOTIDES AT A TIME
