Question

Nucleus contains thread-like structures called ___________.

Answer 1

The nucleus is a membrane-bound organelle which is found in most eukaryotic cells except a few cell types, such as mammalian red blood cells, does not have a nucleus. A nucleus contains the cell’s chromosomes. There are numerous pores in the nuclear membrane which allow for the passage of molecules in and out of the nucleus.

Complete answer:
A DNA molecule in the nucleus of each cell is packaged into thread-like structures called chromosomes. A chromosome is made up of DNA which is tightly coiled or wound around many times around proteins known as histones, which supports its structure. The chromosomes cannot be seen in the cell's nucleus, even under a microscope when the cell is not dividing. But during the process of cell division, the DNA that makes up chromosomes becomes more tightly packed and can be viewed under a microscope. Most of the research work about chromosomes was done by observing chromosomes during the process of cell division. Each chromosome is divided into mainly two sections or arms by a constriction point known as the centromere.
Protein and a single molecule of DNA makes up a chromosome. The DNA contains specific instructions that make each type of living creature unique, which passed from parents to offspring over generations. To ensure DNA is accurately copied and distributed in the vast majority of cell divisions, chromosomes are one of the key parts for this.

So, the right answer to this question is Chromosome.

Note:
The word chromosome comes from Greek words chroma and soma which basically means color and body. Chromosomes are strongly stained by some colorful dyes used in research, which is the main reason for its name. Serious problems or medical conditions can occur when there is a change in the number or structure of chromosomes. In humans, defective chromosomes can cause serious problems such as one type of leukemia and some other cancers.