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40 Cards in this Set
- Front
- Back
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Eukaryotic DNA replication is more complex than the prokaryotic process because of what difference?
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because of multiple origins of replication
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unwinds DNA template at replication fork
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helicase
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prevent strands from reannealing
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single-stranded binding proteins
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creates nick in the helix to relieve supercoils created during replication
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DNA topoisomerase
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(drug) inhibits DNA gyrase--specific prokaryotic topoisomerase)
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Fluoroquinolones
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makes an RNA primer on which DNA polymerase III can initiate replication
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Primase
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elongates leading strand by adding deoxynucleotides to the 3' end
elongates lagging strand until it reaches primer of preceding fragment |
DNA polymerase III
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3' >> 5' exonuclease activity "proofreads" each added nucleotide
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DNA polymerase III
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Degrades RNA primer and fills in the gap with DNA
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DNA polymerase I
(excises RNA primer with 5' >> 3' exonuclease) |
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Seals
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DNA ligase
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Mutated nucleotide excision repair of thymidine dimers
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Xeroderma pigmentosum
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mutated mismatch repair of unmethylated, newly synthesized string
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Hereditary nonpolyposis colorectal cancer (HNPCC)
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drugs blocking DNA replication often have modified 3'OH, preventing addition of the next nucleotide is also known as...
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chain termination
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types of RNA:
largest most abundant smallest |
mRNA
rRNA tRNA |
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site where RNA polymerase and multiple otther transcription factors bind to DNA upstream from gene locus (AT-rich upstream sequence with TATA and CAAT boxes); mutation leads to decreased amount of gene transcribed
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Promoter
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stretch of DNA that alters gene expression by binding transcription factors
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Enhancer
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site where negative regulators (repressors) bind
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Silencer
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makes rRNA
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RNA polymerase I
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makes mRNA
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RNA polymerase II
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makes tRNA
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RNA polymerase III
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inhibits RNA polymerase II' causes liver failure if ingested
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alpha-amanitin
found in death cap mushrooms |
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where does RNA processing in eukaryotes occur? After transcription, give the 3 steps...
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nucleus
1. capping on 5' end (7-methylguanosine) 2. polyadenylation on 3' end (~200 AAs) 3. splicing out of introns |
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capped and tailed transcript is called...
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mRNA
**Poly-A polymerase does NOT require a template |
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what does AAUAAA represent?
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polyadenylation signal
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what is the function of RNA polymerase II in eukaryotes?
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RNA polymerase II opens DNA at promoter site
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segments that contain the actual genetic information coding for protein
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Exons
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intervening noncoding segments of DNA
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Introns
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different exons can be combined to make unique proteins in different tissues via this process..
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alternative splicing
(eg beta-thalassemia mutations) |
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site of:
-rRNA synthesis from rDNA -ribosomal synthesis -ribosome formation |
Nucleolus
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monitors AA before and after it bind to tRHA
if incorrect, bond is hydrolyzed the aa-tRNA bond has energy for formation of peptide bond |
Aminoacyl-tRNA synthetase
"matchmaker" uses ATP |
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a mischarged tRNA reads usual codon but inserts...
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wrong amino acid
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(class of drugs) bind 30S subunit, preventing attachment of aminoacyl-tRNA
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Tetracyclines
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protein synthesis initiation is activated by what process? explain the factors and their role in establishing the complex
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GTP hydrolysis
initiation factors (eIFs) help assemble the 40S ribosomal subunit with the initiator tRNA eIFs are released when the mRNA and the ribosomal subunit assemble with the complex |
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give the 3 phases of protein synthesis elongation...
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1. Aminoacyl-tRNA binds to A site
2. Ribosomal rRNA//ribozyme catalyzes peptide bond formation, transfers growing polypeptide to AA in A site 3. Ribosome advances 3 nucleotides toward 3'end of RNA, moving peptidyl rNA to P site (translocation) |
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stop codon is recognized by release factor, and completed protein is released from ribosome
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termination
(protein synthesis) |
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where does protein translation occur in the cell?
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in the cytoplasm where ribosomes are located (post-leaving nucleolus/nucleus)
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(drug class) inhibit formation of the initiation complex and cause misreading of mRNA
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Aminoglycosides
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(drug) inhibits 50S peptidyltransferase
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Cholarmphenicol
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(drugs) bind 50S, blocking translocation
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Macrolides
Clindamycin |
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process of attaching ubiquitin to defective proteins to tag them for breakdown
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proteasomal degradation
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