Flashcards
day 2 lec 2
Cards in this deck (61)
- 1Similarity of replication between prokaryotes and eukaryotes:Replication begins at a special regions or sequences of chromosomes (bacterial as well as the human genome).
Origin of replicatin - 2DNA Polymerase Carries Out DNA Replication in what direction?5’ to 3’ Direction
- 3lagging strand hasHas Okazaki Fragments
- 4Replication is Semiconservative, meaning?Replicated DNA has one old and one new strand
- 5what is required for DNA replication?primer
- 6DNA polymerse also hasEditing Activity (3’-5’ Exonuclease)
exonuclease to removes mistakes - 7Editing/Proofreadingincreases replication fidelity: error rate is minimized.
- 8where does replicaton begin?origin of replication
- 9diff in origin of rep for pro and euk?Single origin in bacteria and thousands of origin in humans
- 10Bacterial initiator protein (dnaA)also called eukaryotic origin recognition
complex binds to the origin and denatures A-T base pairs - 11Helicaseunwinds double stranded DNA
it is hexameric and ATP dependent - 12whats is a primer?DNA polymerase requires a template and a primer with free 3’-OH group for the synthesis of a polynucleotide strand.
- 13what makes primer?Primase in bacteria
Polymerase a in humans - 14what extends the growing chain during replication?DNA polymerase III (replicase) in bacteria
Polymerase e and d in humans - 15what does polymerase do?adds new nucleotides to the 3’-OH end of the growing chain by copying the template sequence
New bases are complementary to the template strand - 16Primers are removed byby DNA polymerase I in bacteria
RNaseH in humans - 17DNA ligasejoins the fragment
- 18what happens if Inefficient removal of RNA primers?may interfere with genetic readout
- 19Mutations in Rnase H2 have been observed in aneuro-inflammatory disorder and in systemic lupus
- 20what relieves overwinding in DNA?Type II topoisomerase in humans
gyrase in E. coli/bacteria - 21what can interfere with replication?overwinding
- 22types of topoisomerasesType I
Type II - 23Type I TopoisomerasesMake a nick (cut) on only one strand of DNA
- 24Type II Topoisomerases(e.g. bacterial DNA gyrase)
Make two cuts (one cut on each strand - 25Bacterial DNA gyrase (Topoisomerase type II) and topoisomerase IV are target enzymes forquinolones/fluoroquinolones
- 26Mammalian Topo I is the target enzyme foranticancer drugs
- 27Topoisomerase I makes a cut onone strand of the DNA and binds to 3’ end of the phosphodiester back bone
After it relieves the supercoiling, DNA is religated - 28Topotecan (Hycamtin)FDA approved for ovarian cancer and small cell lung cancer
- 29Topotecan stabilizesTopo I-DNA complex and prevents the religation step (inhibition of replication)
- 30Telomeres do 3 thingsseal the ends of chromosome
attach chromosomes to nuclear envelope
facilitate replication - 31why are teloemeres imporant?Prevent undesirable fusion
Prevent aberrant recombination - 32Telomeres have what type of repeats?hexameric repeats
- 33what r the hexameric repeats?TTAGGG in human cells (up to 15 Kb)
TTGGGG in Tetrahymena - 34How are telomeric repeats synthesized?Telomerase
- 35what is Used for AIDS treatmentZidovudine [ZDV; (AZT)]
an analogue of deoxythymidine - 36Deoxyribonucleotides (dATP, dCTP, dGTP, dTTP) are required forreplication
- 37Replication will not occur in the absence ofnucleotides
- 38Thymidylate synthasecatalyzes the synthesis of dTMP
- 39dUMP is a Precursor fordTMP
- 40dTMP is a precursor fordTTP
- 41dTTP is required forDNA replication
Absence of dTTP will prevent DNA replication - 425-FluorouracilInhibits DNA synthesis by inhibiting thymidylate synthase: an enzyme for dTMP synthesis.
- 43Capecitabine (Xeloda)orally-administered chemotherapeutic agent
- 44Capecitabine enzymatically converted tofluorouracil in the body.
- 45Replication errors occur bymispairing of bases or replication slippage.
- 46Post-replicative errors occur bychanges in bases for a variety of reasons.
- 47types of errorsTransitions
Transversions
Frameshifts - 48Transitionssubstitution of a pyrimidine with another pyrimidine or a purine with another purine.
- 49Transversionssubstitution of a pyrimidine with a purine or vice versa.
- 50Frameshiftsdue to addition/deletion of bases
- 51First level of repair/proofreeading during replication3’-5’ exonuclease activity of DNA polymerase
- 523’-5’ exonuclease activity of DNA polymerase3’-5’ exonuclease removes mismatched nucleotide
- 53What happens when replication errors are missed by proofreading activity?Distortion in the DNA helix is recognized and repaired by strand-directed mismatch repair
- 54Post-Replication RepairThe purpose of repair is to correct a mismatched basepair that has escaped proofreading repair.
- 55DNA Repair SystemsBase excision repair (BER)
Nucleotide excision repair (NER) - 56Base excision repair (BER)Specific base is removed and repaired
- 57Nucleotide excision repair (NER)A stretch of DNA strand is removed and new strand with correct base is synthesized
- 58Damage on one strand is repaired by:Base excision repair (BER)
Mismatch repair (MMR)
Nucleotide excision repair (NER) - 59Base excision repair (BER)Non-bulky regions are repaired by glycosylases
- 60Mismatch repair (MMR)Repair of non Watson-Crick basepairs
- 61Nucleotide excision repair (NER)Repair of bulky groups (caused by UV radiations or adduct formation)
Information
- Description
- Flashcards on day 2 lec 2, created by Shylla T on 13/08/2019.
- Created by
- Shylla T
- Views
- 2
- Rating