Chapter 16

12 September 2022
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mismatch repair of DNA (done by DNA polymerase 2)
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repair enzymes correct errors in base pairing
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nucleotide excision repair
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a nuclease cuts out and replaces damaged stretches of DNA
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mutations
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are source of new alleles (genetic variation upon which natural selection operates)
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linear chromosomes
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no way to complete 5' end as repeated rounds of replication produce shorter ends
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telomere
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-eukaryotic chromosomal DNA molecules have special nucleotide sequences at their ends -do not prevent shortening of DNA (postpone erosion of genes near DNA ends) -shortening of telomeres might protect cells from cancerous growth by limiting cell division
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telomerase
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catalyzes the lengthening of telomeres in germ cells (gametes)
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chromatin
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in eukaryotic cell DNA is precisely combined w proteins in chromatin complex -@internphase packed together into 10nm fiber
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euchromatin
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loosely packed chromatin
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heterochromatin
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-during interphase a few regions of chromatin (centromeres+telomeres) are highly condensed into heterochromatin -dense packing of heterochromatin makes it difficult for cell to express genetic info coded in regions
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Who demonstrated that DNA is the genetic material of the T2 phage?
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Hershey and Chase did a series of classic experiments demonstrating that DNA is the genetic material of the T2 phage.
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The radioactive isotope 32P labels the T2 phage's _____.
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The T2 phage consists of a protein coat and DNA. It is the DNA that contains P. The phage's protein coat is not labeled by P.
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Hershey and Chase used _____ to radioactively label the T2 phage's proteins.
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Hershey and Chase used radioactive sulfur to label the phage's proteins. Uranium is not a component of phages.
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After allowing phages grown with bacteria in a medium that contained 32P and 35S, Hershey and Chase used a centrifuge to separate the phage ghosts from the infected cell. They then examined the infected cells and found that they contained _____, which demonstrated that _____ is the phage's genetic material.
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Since the phage DNA entered the infected cell, it makes sense that DNA is the genetic material. A molecule does not have to be labeled in order to be the genetic material.
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helicase
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The role of helicases is to unwind the duplex DNA in order to provide a single-stranded DNA for replication, transcription, and recombination for instanc