How many DNA molecules are there in one chromosome?

When we are in school, we have a biology course. In the process of learning, we can understand the relationship between chromosomes and DNA in the human body. Although we have not yet fully understood the mysteries of the human body, we have a basic understanding of the inheritance of life. For example, the gender of a child is closely related to the chromosomes of its parents. So, how many DNA molecules are there in one chromosome?

The amount of DNA on chromosomes varies at different times.

During the interphase of mitosis, the chromatin replicates and spirals into chromosomes. At this time, the ratio of chromosomes to DNA is 1:2.

In the late stage, the centromere divides the chromosome and the DNA is in a one-to-one relationship

In "×", there is one chromosome but two DNA molecules

In "|" there is one chromosome but one DNA molecule

Remember: the number of chromosomes is determined by the centromere, and the number of DNA is determined by the “|”. A “|” is a double-stranded DNA molecule.

Chromosome is a specific form of genetic material in eukaryotic cells during mitosis or meiosis. It is the result of the tight packaging of the chromatin structure of interphase cells. It is a higher-order structure of chromatin and only appears during cell division. Chromosomes are species-specific, and their number, size, and shape vary with the species, cell type, and developmental stage.

Chromosomes are substances in the cell nucleus that carry genetic information. They appear cylindrical or rod-shaped under a microscope and are mainly composed of DNA and protein. They are easily stained by alkaline dyes (such as gentian violet and acetic acid magenta) during cell mitosis, hence the name.

In asexually reproducing species, all cells in the organism have the same number of chromosomes; in most sexually reproducing species, the chromosomes of the organism's somatic cells are distributed in pairs, containing two chromosome sets, which is called diploid.

Sex cells such as sperm and eggs are haploid, and the number of chromosomes is only half of that of somatic cells. The sex chromosome pair in mammalian male cells is XY, while that in female cells is XX. The sex chromosomes of birds, amphibians, reptiles and some insects are different from those of mammals: males have ZZ and females have ZW.