Question

i need help with 10 and 11 please

The extent of condensation of chromatin plays an important role in the regulation of RNA transcription in eukaryotic cells. Chromatin-remodeling complexes are among proteins that control the physical state and functional activity of chromatin. The experiment described shortly was designed to study the role of a chromatin remodeling complex designated RSC (Remodeling the Structure of Chromatin) in the regulation of nucleosome dynamics. Figure 1 shows the results of an in vitro experiment. The reaction mixtures contained a 32-labelled 154 basepair long DNA fragment, un-labelled nucleosome core particles prepared from rat liver, purified RSC factor, and ATP. Reaction mixtures were incubated at 30C for the times indicated in the figure. Samples were then electrophoresed in a polyacrylamide gel under non-denaturing conditions, the gel was dried and visualized by autoradiography. Sample 6 contained a marker assembled by mixing the labelled 154 bp DNA fragment with nucleosomal histones. RSC ATP Incubation (min) 10 20 40 40 40 Sample 1 2 3 4 5 6 FIG. 1. In vitro analysis of the role of RSC in chromatin remodeling. For experimental details see the text. The arrow indicates the direction of electrophoresis. Figure Analysis: The following statements are related to the information presented in the description of the experiment. Based on the information given, select and again explain your answer. A if the statement is supported by the information given; B if the statement is contradicted by the information given; Cif the statement is neither supported nor contradicted by the information given. 10. The RSC complex stimulates the release of histones from the nucleosomes. Rational: 11 The RSC comnlex stimulates the binding of Dashboard Calendar To Do Notifications Inbox

Answer 1

10) Answer- A
Explanation- Histones are positively charged basic proteins [lysine and arginine rich] that are used in the DNA packaging in Eukaryotes. eight units of histone proteins form a core, which wraps a length of DNA around it to form a structural unit of the chromosome called a nucleosome. hence, nucleosome consists of histone and DNA.
During the transcription of RNA, the decondensation of chromatin is required. The RSC [ Remodelling the structure of chromatin] plays an important role in changing the structure of chromatin. These complex gain energy from ATP[Adenosine triphosphate] and use this energy to alter the structure of the nucleosome and allow the remodeling of chromatin.
From the experiment, it can be observed that the sample 6 does not contain RSC and hence, there is no release of histones from the nucleosomes. Due to which the chromatin remains intact and the DNA is not separated by the Gel electrophoresis. this results in the formation of the band at position "a" [during the separation of fragments by Gel-electrophoresis the larger fragments remain at the top and smaller fragments move away from the well].
11)- Answer- A
Explanation- on observing samples 1,2, and 3 it is clear that the activity of RSC is ATP dependent. It moves the histone core to the DNA fragment [labeled] . with an increase in the incubation time, the width of 'a' is increasing and 'b' is decreasing.