تسجيل الدخول

تسجيل

DNA in Cells

المؤلف:  Max M. Houck، Jay A. Siegel

المصدر:  Fundamentals of Forensic Science

الجزء والصفحة:  P264-265

2026-08-13

20

DNA in Cells

Most cells in the human body have a nucleus. This is where most of the cell’s functions are controlled. Within the nucleus, the DNA is arranged into 46 structures called chromosomes. The chromosomes are arranged in 23 pairs. One member of each pair of chromosomes comes from the father’s sperm cells and the other member comes from the mother’s egg cells. Male sperm contains 23 chromosomes and the female ovum (egg) also contains 23. When a sperm and an egg unite, the 23 chromosomes from the sperm and the egg pair up, forming the 46 found in every nucleated cell in the offspring. One of the 23 pairs of chromosomes determines the sex of the individual. For females, both chromosomes are of the “X” type. In males, one of the chromosomes is X and the other is Y. A cutaway diagram of a human cell is shown in Figure 1. 

FIGURE 1 A cross-section of a human cell. The nucleus contains the genomic DNA. One of the mitochondria present in the cytoplasm is also shown.