Flashcards
Unit 1C
Flashcards do conjunto (46)
- 1what are the models of DNA replicationsemiconservative
conservative
dispersion - 2what is semiconservative DNA replicationeach daughter strand remains paired with its complimentary parental strand
- 3what is conservative DNA replicationafter replication both daughter strands pair up
- 4what is dispersion DNA replicationdaughter strands will have a mixture of parental and newly-synthesized DNA
- 5what is the Meselson and Stahl experimenttracks parental and newly synthesized DNA strands over several generations with nitrogen isotopes. heavy N15 (parental strand) and light N14 (daughter strand).
- 6in the Meselson and Stahl experiment how are the nitrogen isotopes incorporated into the DNA moleculesvia the nitrogenous bases
- 7what provides the energy for the formation of new phosphodiester bondsthe hydrolysis of pyrophosphate
- 8what is the main enzyme in DNA replicationDNA polymerases
- 9what does de novo meanto start from the beginning
- 10since we cannot synthesis a new strand from scratch what do we need and whyA RNA primer that serves as the starting point for DNA replication
- 11what does replisome doits a molecular machine of enzymes that replicate DNA
- 12what does helicase dounwinds the double helix by breaking hydrogen bonds
- 13what does primase dosynthesizes RNA primers for DNA polymerase
- 14what does single-strand binding protein dostabilizes ssDNA before replication by preventing reannealing so that the strands can serve as template
- 15what does DNA topoisomerase/ gyrase doremoves super coils that form ahead of the replication fork, relieves torque of mainly circular DNA
- 16what does DNA polymerase III dosynthesizes DNA by adding nucleotides to the new DNA strand
- 17what does DNA polymerase I doremoves RNA primer and fills the gaps with DNA
- 18what does sliding clamp doattaches DNA Pol III to DNA template, replication is more efficient
- 19what does DNA ligase dojoins the ends of DNA segments by forming phosphodiester bonds
- 20what direction does DNA polymerase synthesize inthe 5'-3' direction
- 21what strand is synthesized continuouslythe leading strand
- 22what strand is synthesized discontinuouslythe lagging strand
- 23what are the small fragments of the lagging strand calledokazaki fragments
- 24what are nickssingle DNA strand breaks in the phosphodiester bonds that need to be repaired
- 25what direction does the template strand read during DNA replication3'-5' direction
- 26what are the steps in DNA replication of bacterial chromosomesinitiation
elongation
termination - 27what is initiationthe unwinding and separation of the 2 template strands at the origin of replication
- 28what is elongationsimultaneous synthesis of the two new DNA strands from the template strands by DNA polymerase
- 29what is terminationDNA replication stops when it reaches a termination site or is at the end of the chromosome
- 30why is the origin of replication made mostly out of A's and T'sbecause there is less hydrogen bonds, so its easier to break
- 31difference in DNA replication of eukaryotic chromosomes and bacterial chromosomeseukaryotic DNA replication has much larger genomes and they have linear chromosomes
- 32how is DNA replication of eukaryotic chromosomes dealt with differently than bacterial chromosomesthere is multiple origins along the chromosomes, and DNA replication proceeds in opposite directions away from the origin
- 33what are the steps in a polymerase chain reaction (DNA replication and amplification in a test tube)denature DNA (95 degrees C)
Primer Anneal (50-60 degrees C)
Strand Extension (72 degrees C)
Repeat for 30 steps (2^30 molecules) - 34why is there a dilemma to replicate ends of linear chromosomesBecause there is a requirement for RNA primer to initiate all DNA synthesis, when the primer is removed there is a gap that cannot be filled by DNA polymerase. Each round of replication leads to a shorter chromosome
- 35what is telomerasenoncoding DNA that is added to the 3' end of the chromosome, in which it usually repeats of 5-8 G's and T's. this basically restores shortened telomeres
- 36what is the difference between youth and older people's telomeresolder people: have shorter telomeres
youth: have longer telomeres - 37what type of cells is telomerase present ingametes, stem cells, and cancer cells
- 38failure to maintain high fidelity of DNA replication causes .... and could result in...it causes defective genomes and could result in cancer and death of organism
- 39what ensures that replication error rate is 1/10,000,000,000 nucleotidesDNA repair mechanisms mediated by enzyme complexes
- 40what enzyme proofreadsDNA polymerase
- 41DNA Pol III synthesizes new strands in what direction5'-3' direction
- 42how does DNA polymerase proofreadit detects mistakes and uses 3'-5' exonuclease activity to remove the most recent mismatched nucleotides by cleaving the phosphodiester bonds
- 43what is nucleotide excision repairit recognizes distortions in the DNA helix caused by nucleotide lesions
- 44what are the steps of nucleotide excision repair1) recognition of DNA damage
2) UvrB helicase breaks hydrogen bonds creating a bubble
3) UvrC endonuclease cuts two phosphodiester bonds
4) 12 bp sequence is cut away by UvrD helicase by breaking hydrogen bonds
5) The gap is filled by DNA Pol I
6) The nick is repaired by DNA ligase - 45what is base excision repairfixes nucleotide lesions that do not cause substantial distortions in the DNA helix
- 46how is base excision repair doneDNA uracil glycosylases breaks the bond between the sugar and base creating apurinic and apyrimidinic sites. The AP sites are recognized by AP endonuclease which cleaves the phosphodiester bonds. Then DNA polymerase and ligase fill the gap
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- Biology 243 - Lecture component FlashCards sobre Unit 1C, criado por Chelsea Scheck em 23-01-2019.
- Criado por
- Chelsea Scheck
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