Advertisements
Advertisements
Questions
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.
Advertisements
Solution 1
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.
Solution 2
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.
APPEARS IN
RELATED QUESTIONS
Differentiate between Euchromatin and Heterochromatin.
Name the transcriptionally active region of chromatin in a nucleus.
Although a prokaryotic cell has no defined nucleus, yet DNA is not scattered throughout the cell. Explain.
In an octamer of the nucleosome, core DNA consists of ______ base pairs.
Short Answer Question:
Write a short note on DNA packaging in the eukaryotic cell.
Differentiate between Heterochromatin & Euchromatin.
Draw a neat and labelled diagram of the Nucleosome.
A typical nucleosome "bead" is made up of ______.
The additional set of proteins required for packaging of chromatin at higher level are called ______.
Barr body in mammals represents ______.
Histone proteins are ______.
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?
Histones are rich in ______.
Whittaker placed prokaryotes in:
Plasmid has been used as vector because ______.
During translation initiation in prokaryotes, a GTP molecule is needed in:
Which one of the following statements about Histones is wrong?
Distinguish between heterochromatin and euchromatin. Which of the two is transcriptionally active?
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.
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?
The most abundant prokaryotes helpful to human in making curd from milk and in the production of antibiotics are the ones categorised as ______ .
Total ATP production during EMP pathway is ______.
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:
