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प्रश्न
Describe the structure of a nucleosome.
With the help of a suitable diagram describe the structure of a nucleosome
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उत्तर १
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.
उत्तर २
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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संबंधित प्रश्न
How are the following formed and involved in DNA packaging in a nucleus of a cell?
(ii) Nucleosome
(iii) Chromatin
Differentiate between Euchromatin and Heterochromatin.
In an octamer of the nucleosome, core DNA consists of ______ base pairs.
Attempt any TWO of the following:
With the help of a suitable example illustrate ‘Palindrome’.
Differentiate between Heterochromatin & Euchromatin.
Draw a neat and labelled diagram of the Nucleosome.
Write a note on the packaging of DNA in prokaryotes.
Explain the formation of a nucleosome.
A typical nucleosome "bead" is made up of ______.
The octamer of histone protein is made of ______.
The length of DNA segment having 44 base pairs is ______
Nucleosome core is made of ______.
Barr body in mammals represents ______.
Histone proteins are ______.
Find out the wrong statement about heterochromatin.
Read the following and answer from given below:
The process of copying genetic information from the template strand of DNA into RNA is called transcription. It is mediated by RNA polymerase. Transcription takes place in the nucleus of eukaryotic cells. In transcription, only a segment of DNA and only one of the strands is copied into RNA.
Monocistronic structural genes are found in which organisms?
Read the following and answer from given below:
The translation is the process of polymerization of amino acids to form a polypeptide. The order and sequence of amino acids are defined by the sequence bases in the mRNA. The amino acids are joined by a bond called a peptide bond. The ribosome is the site of protein synthesis.
During translation, how many initiation factors are required in eukaryotes for initiation reactions?
Whittaker placed prokaryotes in:
Which process occurs in the regulation of gene expression in prokaryotes but does not occur in the regulation of gene expression in eukaryotes?
Watson and Crick proposed the 'Double Helix' structure of DNA based on data produced by ______
In an experiment, DNA is treated with a compound which tends to place itself amongst the stacks of nitrogenous base pairs. As a result of which, the distance between two consecutive base increases, from 0.34nm to 0.44 nm. Calculate the length of DNA double helix (which has 2 × 109 bp) in the presence of saturating amount of this compound.
Which of the following amino acid residues will constitute the histone core?
What do the 'beads on strings' structure of DNA packaging represent?
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.
