Question

Eukaryotic chromosomes are thousands times longer than a typical cell. How do chromosomes fit inside a eukaryotic nucleus?

• A. The genetic material remains distributed in the nucleus, mitochondria, and chloroplast
• B. The chromosome is present in pieces, thus it fits the size of the nucleus
• C. The DNA remains coiled around proteins to form nucleosomes which further coils to compact itself
• D. The genetic material remains bound to the nuclear envelope, forming invaginations

Answer 1

The correct option is C The DNA remains coiled around proteins to form nucleosomes which further coils to compact itself

While we refer to the condensed form of DNA that we see during cell division as chromosomes, when the cell is not dividing, the chromosome is nothing but a single long DNA molecule.

This DNA molecule is too long to fit inside the cell. So the DNA molecule coils around protein octamer (called histones) to form coiled structures called "nucleosomes". Winding of such long DNA around the histones makes the chromosome a compact structure.

During cell division, this structure further coils around itself to become more compact and looks more like the chromosome that we know. It is a lot more easier to fit the compact chromosome structure within the eukaryotic nucleus.