Genetics Exam 3 Outline

Genetics Exam 3 Outline - DNA Replication Semi-conservative...

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DNA Replication Semi-conservative: double stranded DNA, the parent strands, are not broken down, but are separated to be used as templates with opposite polarity DNA Template: genetic sequence for new strands DNA polymerase: enzyme for replication that requires a 3’ end to add 5’-dNTPs in the presence of a template strand in order to synthesize DNA Breaks phosphodiester backbone reverse transcriptase: RNA-dependent DNA polymerase that transcribes single- stranded RNA into DNA adds 1000+ bases per second, including proofreading Telomerase: a reverse transcriptase enzyme in eukaryotes that carries an RNA template to extend and repeat its sequence at the 3’ end in the telomere regions Needed as a stabilizing protein plug after repeated shortening of DNA strand by replication and nucleases Cell provides trinucleotides/codons Transcription: RNA polymerase synthesizes RNA chains with direction of DNA sense strands to produce mRNA in order to synthesize proteins RNA Template: strand of RNA that translates genes into proteins RNA polymerase: an enzyme that makes an RNA template from DNA and is needed for transcription in 5’ to 3’ direction Sequence-specific (-10 and -35 sequences): if a base is changed, the binding of RNA polymerase is reduced, altering rate of transcription
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Increase transcription by using an “ideal” sequence recognized most easily Sequence and spacing are extremely important I. large rRNAs that make up ribosomal RNA II. mRNA III. tRNA, small RNA, snRNA Substrates: tri-phosphates used for DNA replication (5’-dATP, 5’-dGTP, 5’-TTP, 5’-dCTP) Nicked DNA: a cut in one strand of a double-stranded DNA molecule where there is no phosphodiester bond between adjacent nucleotides, resulting from the absence of DNA ligase one nick generates a 5’ end and a 3’ end Mismatch Repair: when a nick is made in the DNA, a mismatched base is removed, DNA polymerase inserts the complementary base, and DNA ligase seals it Okazaki Fragment: relatively short fragment of DNA with an RNA primer at the 5’ terminus
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Genetics Exam 3 Outline - DNA Replication Semi-conservative...

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