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प्रश्न
Describe the structure of a nucleosome.
With the help of a suitable diagram describe the structure of a nucleosome
Describe the structure of a nucleosome, with the help of a well-labelled diagram.
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उत्तर १
In eukaryotes, the packaging of the DNA helix is very complex, as the amount of DNA is very high. When we analyse the structure of the 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 a histone octamer. The negatively charged DNA molecule gets wrapped around this positively charged histone octamer. This complex structure is called a nucleosome. In a typical nucleosome, around 200 base pairs of DNA are present.
उत्तर २
The nucleosomes in chromatin are seen as ‘beads-on-string’. Histones are proteins that are rich in the basic amino acid residues, such as 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 organised to form a histone octamer. DNA is negatively charged, and it is wrapped around the positively charged histone octamer to form the nucleosome. Around the octamer, the DNA molecule is wrapped in 1 and 3/4th turn. The DNA is called core DNA (146 bp), and small segments of DNA linking the octamer are called linker DNA (54 bp). Each nucleosome contains 200 bp of DNA helix.
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संबंधित प्रश्न
How are the following formed and involved in DNA packaging in a nucleus of a cell?
(ii) Nucleosome
(iii) Chromatin
Explain the role of histones in forming a nucleosome.
Attempt any TWO of the following:
With the help of a suitable example illustrate ‘Palindrome’.
Find the odd one out:
Differentiate between Heterochromatin & Euchromatin.
Draw a neat and labelled diagram of the Nucleosome.
Write a note on the packaging of DNA in prokaryotes.
In prokaryotes, the enzyme RNA polymerase recognizes the promoter by its ______.
A typical nucleosome "bead" is made up of ______.
The length of DNA can be calculated by ______.
Telomere has a unique property of __________.
The length of DNA segment having 44 base pairs is ______
The net electric charge on DNA and histones is ______.
Nucleosome core is made of ______.
Histone proteins are ______.
Find out the wrong statement about heterochromatin.
Flagella are present both in prokaryotic and eukaryotic cells, however, they differ in:
Electron Transport System (ETS) is present in a eukaryotic cell in the:
Whittaker placed prokaryotes in:
During translation initiation in prokaryotes, a GTP molecule is needed in:
What is the function of histones in DNA packaging?
What would happen if histones were to be mutated and made rich in acidic amino acids such as aspartic acid and glutamic acid in place of basic amino acids such as lysine and arginine?
Which of the following amino acid residues will constitute the histone core?
Part of chromatins which is densely packed stain darkly and is transcriptionally inactive is called ______.
Total ATP production during EMP pathway is ______.
Define the Transfection.
Nucleosomes are the repeating units of chromatin the part between adjacent nucleosomes is called ______ .
Statement I: In prokaryotes, the positively charged DNA is held with some negatively charged proteins in a region called nucleoid.
Statement II: In eukaryotes, the negatively charged DNA is wrapped around the positively charged histone octamer to form nucleosome.
In the light of the above statements, choose the correct answer from the options given below:
