Question

what do you mean by packaging of dna??​

Answer 1

✏ Answer

● The DNA probe binds with the complementary sequences of the DNA fragments on the membrane to form a hybridised DNA.

● DNA being negatively charged is held with some proteins (polyamines) that have negatively charges in a region termed as nucleiod.

● In eukaryotes, the organisation of DNA is much more complex.

● A protein acquires charge due to the abundance of aminoacid residues with charged side chains.

● Their charged ends are towards outside.

● The negatively charged DNA is wrapped around positively charged histone octomer amost twice to form nucleosome.

Answer 2

The DNA is an organic, complex, molecular structure, found in both prokaryotic and eukaryotic cells and also in many viruses. It is a hereditary material that is found in the nucleus of the cell and is mainly involved in carrying genetic information.

The DNA structure has the following characteristics:

• The strands of the DNA are helically wounded, every single strand forms a right-handed coil.
• The pitch of each helix is 3.32 nm and about 10 nucleotides make up one turn.
• The distance between two succeeding base pairs is 0.34 nm
• The total length of a DNA is the distance between two succeeding base pairs and the product of a total number of base pairs.
• A typical DNA has an extent around 2.2 meters, which is much longer than a nucleus.

Prokaryotic cells can be distinguished from eukaryotic cells by the presence of a well-defined nucleus. However, their negatively charged DNA is arranged in a region called the nucleoid. They appear as a loop wrapped around a protein molecule having a positive charge.

All eukaryotes have a well-defined nucleus that contains DNA. DNA is a negatively charged polymer, packed compactly within the chromatin engirdling the histone proteins, a ball of positively charged proteins.

The octamer of histone proteins is wrapped with a DNA helix, giving rise to a structure called a nucleosome. The nucleosomes are further coiled which results in the formation of chromatin fibres. Chromatin fibres are stained thread-like structures whereas nucleosomes are beads present over them. These chromatin fibres condense to form chromosomes during mitosis.