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32 Cards in this Set
- Front
- Back
Pyrimidines: define and list
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contain 1 carbon-nitrogen ring
C and T |
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Pyrimidines: define and list
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contain 1 carbon-nitrogen ring
C and T |
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Purines: define and list
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contain double carbon ring
A and G |
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What is the purpose of DNA helicase
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to unwind the double helix
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What is the purpose of DNA topoisomerase?
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to remove supercoils
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What is the direction of DNA replication? (synthesis)
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synthesize 5'-->3'
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What is the purpose of DnaA protein in prokaryotic replication?
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melts AT-rich consensus sequence at origin to separate DNA (requires ATP)
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What is the purpose of the alpha subunit of DNA polymerase III?
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primase (makes primer)
5'-->3' polymerase activity |
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What is the purpose of the delta subunit of DNA polymerase III?
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completes synthesis
3'-->5' exonuclease activity (proofreads) |
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What is the purpose of the beta and epsilon subunit of DNA polymerase III?
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exonuclease activity (proofreads); also involved in repair
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What is the purpose of pol gamma? (the eukaryotic DNA polymerase)
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replicates mitochondrial DNA
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What is the purpose(2) of telomerase? How does it work?
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(1) Replaces primer on 5' lagging strand. (2) Provide end stability Adds TG-rich "telomeres" to extend the 3' end using CG-rich template
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What is the purpose/result of reverse transcriptase?
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RNA-->DNA using RNA directed polymerases
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What are transposons?
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DNA elements that can insert and move about the genome
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What is allelic heterogeneity?
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different mutations at the same locus cause the same disorder
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What is phenocopy?
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an individual whose phenotype, under a particular environmental condition, is identical to the one of another individual whose phenotype is determined by the genotype
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What is locus heterogeneity?
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genetic conditions where a single syndrome is caused by different genes in different families, possibly due to the different environmental factors that have influenced them
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What is homologous recombination?
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a type of genetic recombination in which nucleotide sequences are exchanged between two similar or identical molecules of DNA
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What is a sigma factor (σ factor)?
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a prokaryotic transcription initiation factor that enables specific binding of RNA polymerase to gene promoters
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What are snRNPs (small nuclear ribonucleoproteins)?
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RNA-protein complexes that combine with unmodified pre-mRNA and various other proteins to form a spliceosome, a large RNA-protein molecular complex upon which splicing of pre-mRNA occurs
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What is TFIID? What does it do?
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one of several general transcription factors that make up the RNA polymerase II preinitiation complex. Before the start of transcription, the transcription Factor II D (TFIID) complex, consisting of TFIID, TBP, and at least nine other polypeptides, binds to the TATA box in the core promoter of the gene.
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What is TFIIA? What does it do?
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specifically required for transcription of 5S rRNA genes and is the archetypal C2H2 zinc finger protein
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What are DNA polymerase I's enzymatic activities?
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(1) 5' -> 3' DNA polymerase activity (2) 3' -> 5' exonuclease activity that mediates proofreading (3) 5' -> 3' exonuclease activity mediating nick translation during DNA repair
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define/describe DNA polymerase II
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most likely involved in DNA repair; lacks a 5'->3' exonuclease activity
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What are the subunits of DNA polymerase III and their purposes?
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the α subunit has polymerization activity.
the ε subunit has proofreading activity. the θ subunit stimulates the ε subunit's proofreading. |
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What is the signal hypothesis?
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The major mechanism whereby proteins that insert into or cross a membrane are synthesized by a membrane-bound ribosome. The first thirteen to thirty-six amino acids synthesized, termed a signal peptide, are recognized by a signal recognition particle that draws the ribosome to the membrane surface by interaction with a docking protein. The signal peptide may later be removed from the protein.
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What does RNA polymerase I transcribe?
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rRNA
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What does RNA polymerase II transcribe?
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precursors of mRNA and most snRNA and microRNA
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What does RNA polymerase III transcribe?
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ribosomal 5S rRNA, tRNA and other small RNAs
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Define haplo-insufficiency
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when a diploid organism only has a single functional copy of a gene and the single functional copy of the gene does not produce enough of a gene product
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Define transversion mutation.
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the substitution of a purine for a pyrimidine or vice versa
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Define transition mutation.
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a point mutation that changes a purine nucleotide to another purine or a pyrimidine nucleotide to another pyrimidine.
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