QB08-Dv2 - BIO320 Question bank D; lectures 21-23. I....

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BIO320 – Question bank D; lectures 21-23. I. Eukaryotic chromosomes, chromatin & gene expression (lecture 20) 1. These are various substructures in the arrangement of eukaryotic DNA. Number them in order of increasing size (i.e. diameter or thickness): DNA helix, chromatid, 30nm fiber, nucleosome, chromosome, histone octamer. 2. The total length of the DNA in a diploid set of human chromosomes is about 2 meters, yet this DNA must fit into a nucleus that is less than 10 mM (10 -5 m) in diameter. This is accomplished by: A. Removal by splicing of the introns and other non-coding regions that make up the bulk of the DNA. B. Several levels of coiling and looping, beginning with the coiling of DNA into nucleosomes. C. Cutting the DNA into short lengths by DNAse I and other endonucleases. D. Hyperacetylation of histone proteins. E. Inactivation and condensation of one homolog from each chromosome pair. 3. Which of the following statements about the histones and nucleosomes in eukaryotic chromatin is FALSE: A. Nucleosomes recognize and bind to specific DNA base sequences. B. The core nucleosome comprises two copies each of four histone proteins. C. The DNA helix is wound around the outside of each nucleosome. D. Modification of histones can affect chromatin structure and gene expression. E. Histones are basic proteins with positively charged residues that interact with the negatively charged phosphate groups on DNA 4. Which of the following structures enables separation of sister chromatids by spindle microtubules at mitosis? A) centromeres B) telomeres C) origins of replication D) nucleosomes E) DNAse hypersensitive sites 5. Which of the following statements about histones is FALSE A) Positively charged amino acids on histones contact the negatively charged phosphates on the DNA backbone. B) Adding acetyl groups to specific amino acids on histones can change the condensation state of chromatin. C) Histones are highly conserved, basic proteins. D) About 150bp of DNA is wound around eight histone proteins to form a nucleosome. E) Histones in a nucleosome make many close contacts with DNA bases in the major groove. 6. Which of the following statements about the histones and nucleosomes in eukaryotic chromatin is FALSE: A) About 145bp of DNA is wound around the outside of each nucleosome. B) The core nucleosome includes two copies each of four histone proteins. . C) Nucleosomes bind to specific DNA sequences, usually near gene promoters. D) Histone acetylation can affect chromatin condensation and gene expression. E) Histones are basic proteins with positively charged residues which interact with the negatively charged phosphate groups on DNA. 7. If chromatin is digested briefly with certain endonuclease enzymes, and the genomic DNA is then isolated and electrophoresed on a gel, a ladder pattern is seen with DNA fragments differing in size by increments of about 150 bp. This happens because these endonucleases: A. always cut any DNA strand at 150-base intervals.
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This note was uploaded on 09/28/2009 for the course BIO 320 taught by Professor N/a during the Spring '08 term at SUNY Stony Brook.

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QB08-Dv2 - BIO320 Question bank D; lectures 21-23. I....

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