How 2.2m DNA is kept inside cell.
When cell is 0.01m
Answers
Answer:
The length of the DNA maybe long. But the DNA molecules are compactly packed at many different levels to fit inside a 0.01m cell.
Explanation:
human DNA has a length of around 2m. But it has to be packed in a small 0.01m cell, so DNA undergoes different levels of DNA packaging and it will be compactly packed to fit inside the cell.
the organization of DNA in the nucleus is much more complex and is as follows:
The negatively-charged DNA is wrapped around a positively-charged histone octamer i.e. a unit of 8 histone molecules. This forms a ‘Nucleosome‘. Histones are positively-charged proteins that are rich in basic amino acids – arginines and lysines. A typical nucleosome has 200bp of DNA helix.
Many nucleosomes join together to form a thread-like structure – Chromatin in the nucleus. The nucleosomes in chromatin appear as ‘beads-on-string’ under the electron microscope.
The chromatin is packaged to form chromatin fibres which are further coiled and condensed to form chromosomes. The higher level packaging of chromatin requires another set of proteins – Non-histone Chromosomal (NHC) proteins.