BCHM 218 Exam Questions and Answers 100% Pass
Chromatin is composed of: - Correct Answer️️ -DNA and protein
Of the proteins associated with chromatin, which of the following represents the largest
component? - Correct Answer️️ -Histones
The first evidence for nucleosome formation came f...
BCHM 218 Exam Questions and Answers 100% Pass Chromatin is composed of: - Correct Answer ✔️✔️-DNA and protein Of the proteins associated with chromatin, which of the following represents the largest component? - Correct Answer ✔️✔️-Histones The first evidence for nucleosome formation came from digesting chromosomal DNA with a non -specific nuclease. Gel electrophoresis of the DNA after the reaction revealed: - Correct Answer✔️✔️-A large band corresponding to 200bp Each nucleosome contains: - Correct Answer ✔️✔️-a histone octomer composed of t wo copies of H2A, H2B, H3 AND H4 Nucleosome structure - Correct Answer ✔️✔️-- about 200BP of DNA wrapped around a histone core - the DNA wraps around the core nearly 2X forming a right -handed solenoidal supercoil Histones - Correct Answer ✔️✔️-- highly conse rved sequences among eukaryotes - rich in basic AA's (Lys, Arg) - Small proteins - contain a histone -fold motif comprised of three a -helices linked by two short loops The contacts between the DNA and the histones of nucleosomes are: - Correct Answer✔️✔️-primarily between DNA and the histone peptide backbone T or F, histone tails have enzymatic properties that can covalently modify DNA - Correct Answer✔️✔️-F T of F, Binding of H1 destabilizes the nucleosome, alleviating the transcriptional repression exerted by the binding of nucleosome histones - Correct Answer ✔️✔️-F How is H1 binding different than that of the other four histones - Correct Answer ✔️✔️-H1 binds to one strand of the linker DNA as it comes off the nucleosome and binds a second site in the central region of the DNA supercoil. What are 3 functions of histone H1? - Correct Answer ✔️✔️-- stabalizing nucleosomes - promoting higher order chromosome stru cture - enhancing the repression of transcription by nucleosomes Higher chromosome structure depends on: - Correct Answer ✔️✔️-SMC proteins, one of the major components of the chromosome scaffold Why is histone H1 referred to as the linker histone? - Correc t Answer ✔️✔️-:When chromatin is treated with nucleases, initially a larger portion of the DNA is protected, but when more extensive digestion is carried out and H1 is released the DNA fragment protected is smaller. This shows that H1 binds to linker DNA un like the histones of the nucleosome In SDS -polyacrylamide gel electrophoresis proteins are partially denatured and separated entirely as a function of their mass. Histones are an exception; they migrate more slowly than they should, as though they are much larger than they actually are. Why does this occur? - Correct Answer ✔️✔️-Histones have a large number of positively charged amino acid residues. The binding of SDS to the histones is not sufficient to mask these charges resulting in slower migration. ways chromatin remodeling complexes affect nucleosomes - Correct Answer ✔️✔️--move -eject -replace A histone modification that attracts other proteins such as a transcription factor is said to be acting: - Correct Answer ✔️✔️-In trans. SWI/SNF complexes - Correc t Answer ✔️✔️-avtivation Which method can be used to determine the position of nucleosomes in the genome? - Correct Answer ✔️✔️-chIP-seq Which of the following is the third step of a ChIP -Seq protocol? - Correct Answer ✔️✔️-
Immunoprecipitation of nucleosome -DNA complexes with histone antibody. Histone chaperones: - Correct Answer ✔️✔️-Are acidic proteins that bind to H2A -H2B dimers and H3 -H4 tetramers before assembly into nucleosomes. Proteins that bind to acetylated lysine residues in the histone tail contain: - Correct Answer✔️✔️-Bromodomains Activation of the IFN -β globin promoter is an example of a histone code. what is the 3rd step in this process? - Correct Answer ✔️✔️-A chromatin remodeling complex such as SW1/SNF binds to and moves the nucleosome How can the disruption of epigenetic markers result in cancer? - Correct Answer ✔️✔️-
The disruption of epigenetic pathways can activate genes that promote cell growth or repress genes that limit cell growth, leading to tumor formation. From their detailed compariso ns of the genomes of bacteria and archea, Drs. Eugene Koonin and William Martin observed that: - Correct Answer ✔️✔️-archea and bacteria broadly share the same mechanisms and enzymes for protein synthesis, but not for DNA replication Watson and Crick proposed that during DNA replication the double helix is unwound and each parental DNA strad is used as a template to generate a new daughter strand. What is this mode of replication called? - Correct Answer ✔️✔️-semiconservative The direct ion of synthesis of DNA polymerases refers to: - Correct Answer ✔️✔️-The direction in which each new nucleotide is chemically linked to the growing daughter strand Why does the replication fork require both leading and lagging strand synthesis? - Correct An swer✔️✔️-because the DNA templates are antiparallel and yet the DNA polymerases only work in one direction Which of the following is NOT necessary for DNApolymerase reaction? template DNA, primer strand, ATP, dNTP's - Correct Answer ✔️✔️-ATP what is require d for nick translation? - Correct Answer ✔️✔️-5'-3' exonuclease and 5' -3' polymerase
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