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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
Differentiate between Euchromatin and Heterochromatin.
Although a prokaryotic cell has no defined nucleus, yet DNA is not scattered throughout the cell. Explain.
Attempt any TWO of the following:
With the help of a suitable example illustrate ‘Palindrome’.
Very Short Answer Question:
Which are the nucleosomal 'core' histones?
Find the odd one out:
Write a note on the packaging of DNA in prokaryotes.
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The octamer of histone protein is made of ______.
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The net electric charge on DNA and histones is ______.
The structure in chromatin seen as ‘beads-on string’ when viewed under electron microscope are called ______.
Read the following and answer from given below:
In prokaryotes, DNA is circular and present in the cytoplasm but in eukaryotes, DNA is linear and mainly confined to the nucleus. DNA or deoxyribonucleic acid is a long polymer of nucleotides. In 1953, the first correct double-helical structure of DNA was worked out by Watson and Crick. Based on the X-ray diffraction data produced by Maurice Wilkins and Rosalind Franklin. It is composed of three components, i.e., A phosphate group, a deoxyribose sugar, and a nitrogenous base. Different forms of DNA are B-DNA, Z-DNA, A-DNA, C-DNA, and D-DNA.
Name the linkage present between the nitrogen base and pentose sugar in DNA.
Read the following and answer from given below:
In prokaryotes, DNA is circular and present in the cytoplasm but in eukaryotes, DNA is linear and mainly confined to the nucleus. DNA or deoxyribonucleic acid is a long polymer of nucleotides. In 1953, the first correct double-helical structure of DNA was worked out by Watson and Crick. Based on the X-ray diffraction data produced by Maurice Wilkins and Rosalind Franklin. It is composed of three components, i.e., A phosphate group, a deoxyribose sugar, and a nitrogenous base. Different forms of DNA are B-DNA, Z-DNA, A-DNA, C-DNA, and D-DNA.
The double helix structure of DNA was proposed by ______
Read the following and answer from given below:
In prokaryotes, DNA is circular and present in the cytoplasm but in eukaryotes, DNA is linear and mainly confined to the nucleus. DNA or deoxyribonucleic acid is a long polymer of nucleotides. In 1953, the first correct double-helical structure of DNA was worked out by Watson and Crick. Based on the X-ray diffraction data produced by Maurice Wilkins and Rosalind Franklin. It is composed of three components, i.e., A phosphate group, a deoxyribose sugar, and a nitrogenous base. Different forms of DNA are B-DNA, Z-DNA, A-DNA, C-DNA, and D-DNA.
The double chain of B-DNA is coiled in a helical fashion. The spiral twisting of the B-DNA duplex produces ______
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.
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______ are the amino acids of histones.
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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.
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Total ATP production during EMP pathway is ______.
Name the enzymes involved in replacement of gaps during RNA processing in prokaryotes and eukaryotes.
Who among the following has developed technique to synthesize artificial mRNA with known repeated sequences of two or three nucleotides?
