What name is given to the structures in the nucleus which are made of large molecules of DNA?

The structures in the nucleus that are composed of large molecules of DNA are called chromosomes. Chromosomes are thread-like structures that carry genetic information organized in the form of genes. Each human cell typically contains 46 chromosomes, arranged in 23 pairs, with one set inherited from each parent.

During the cell cycle, specifically during cell division (mitosis or meiosis), chromosomes become tightly packed, making them visible under a microscope. When the cell is not dividing, DNA exists in a more relaxed state, called chromatin, which allows for transcription and DNA replication. Each chromosome consists of a single continuous molecule of DNA wrapped around proteins called histones, which help to organize and compact the DNA, making it easier for the cell to manage its genetic material effectively.