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Questions
Describe the structure of a nucleosome.
With the help of a suitable diagram describe the structure of a nucleosome
Solution 1
In eukaryotes, the packaging of DNA helix is very complex, as the amount of DNA is very high. When we analyze the structure of eukaryotic chromosome, we find that it is composed of DNA and proteins. These proteins, known as histones, are basic in nature and are positively charged. Thus, they can easily interact with the negatively charged DNA molecule. The histone proteins first organise to make a unit of eight molecules, which is known as histone octamer. The negatively charged DNA molecule gets wrapped around this positively charged histone octamer. This complex structure is called nucleosome. In a typical nucleosome, around 200 base pairs of DNA are present.
Solution 2
The nucleosomes in chromatin are seen as ‘beads-on-string’. Histones are proteins that are rich in the basic amino acid residues like lysines and arginines which carry the positive charge in their side chains. Eight molecules of histones (two each of H2A, H2B, H3 and H4) get organized to form histone octamer. DNA is negatively charged and it is wrapped around the positively charged histone octamer to form the nucleosome. Around the octamer, DNA molecule is wrapped as 1 and 3/4th turn. The DNA is called core DNA (146 bp) and small segments of DNA linking octamer are called linker DNA (54 bp). Each nucleosome contains 200 bp of DNA helix.
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Short Answer Question:
Write a short note on DNA packaging in the eukaryotic cell.
Differentiate between Heterochromatin & Euchromatin.
Draw neat and labelled diagram of the Nucleosome.
In prokaryotes, the enzyme RNA polymerase recognizes the promoter by its ______.
A typical nucleosome "bead" is made up of ______.
The additional set of proteins required for packaging of chromatin at higher level are called ______.
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The chromatin is packed to form a solenoid structure of ______ diameter.
Telomere has a unique property of __________.
Histone proteins are ______.
Find out the wrong statement about heterochromatin.
Which one of the following cell organelle is considered as ‘Cell within a cell’?
Electron Transport System (ETS) is present in a eukaryotic cell in the:
Histones are rich in ______.
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Which one of the following is not considered as part of the endomembrane system?
In the eukaryotic cell cycle, cell fusion experiments show that:
During translation initiation in prokaryotes, a GTP molecule is needed in:
Distinguish between heterochromatin and euchromatin. Which of the two is transcriptionally active?
What do the 'beads on strings' structure of DNA packaging represent?
The most abundant prokaryotes helpful to human in making curd from milk and in the production of antibiotics are the ones categorised as ______ .
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Distinguish between heterochromatin and euchromatin with reference to staining property and activity.
Total ATP production during EMP pathway is ______.
Name the enzymes involved in replacement of gaps during RNA processing in prokaryotes and eukaryotes.
Define the Transfection.
