A typical mammalian cell has 22 meters long DNA molecule whereas the nucleus in which it is packed measure about - Biology - Molecular Basis of Inheritance

Question

A typical mammalian cell has 22 meters long DNA molecule whereas
the nucleus in which
it is packed measure about 10-6 m Explain in how such a long DNA
molecule is packedwithin a tiny nucleus in the cell

Manik Mishra · Accepted Answer

The long sized DNA are accomodated in small areas through packing
or compaction DNA is acidic due to presence of a large number of
phosphate groups Compaction takes place by folding and attachment
of DNA with basic proteins called histones The unit of compaction
is called nucleosome The compaction is carried out with the help of
lysine and arginine rich basic proteins called histones Five types
of histone proteins are found in nucleus: H1,
H2, H2B, H3 and H4 Four
of them (H2A, H2B, H3 and
H4) occur in pairs to produce histone octamer or core of
nucleosome Their positively charged ends lie towards the outside
They attract negatively charges strands of DNA Linker DNA is the
DNA connecting two adjacent nucleosomes It bears H1
histone protein Length of linker DNA is varied The nucleosomal
organization has approximately 10 nm thickness which gets further
condensed and coiled to produce a solenoid of 30 nm This solenoid
structure undergoes further coiling and produce a chromatin fiber
of 30-80 nm and than a chromatid of 700 nm The chromatid undergoes
a further coiling and produce a chromosome of 1400 nm

A typical mammalian cell has 22 meters long DNA molecule whereas the nucleus in whichit is packed measure about 10-6 m. Explain in how such a long DNA molecule is packedwithin a tiny nucleus in the cell.

A typical mammalian cell has 22 meters long DNA molecule whereas the nucleus in which
it is packed measure about 10-6 m. Explain in how such a long DNA molecule is packedwithin a tiny nucleus in the cell.