How many chromosomes does a mature human sperm cell contain?
A. 1
B. 2
C. 23
D. 46
The correct answer and explanation is:
The correct answer is C. 23.
A mature human sperm cell contains 23 chromosomes. This number is half the total number of chromosomes found in most human body cells, which have 46 chromosomes. Human cells that are not involved in reproduction, called somatic cells, are diploid, meaning they have two sets of chromosomes — one set inherited from the mother and one from the father. This totals 46 chromosomes arranged in 23 pairs.
Sperm cells, however, are gametes or sex cells. These cells are haploid, which means they contain only one set of chromosomes, or 23 unpaired chromosomes. This reduction in chromosome number occurs during a special type of cell division called meiosis. Meiosis reduces the chromosome number by half to ensure that when fertilization occurs, the resulting zygote will have the correct diploid number of 46 chromosomes.
During fertilization, the sperm cell contributes its 23 chromosomes to the egg cell, which also contains 23 chromosomes. When these two sets combine, the zygote receives a complete set of 46 chromosomes, restoring the diploid state. This process ensures genetic stability across generations.
The presence of 23 chromosomes in sperm cells is essential for normal human development. Any deviation from this number, such as in cases of nondisjunction during meiosis, can lead to chromosomal disorders. Examples include Down syndrome, which results from an extra copy of chromosome 21.
In summary, the sperm cell contains 23 chromosomes to combine with the egg’s 23 chromosomes during fertilization. This maintains the species’ chromosome number and ensures proper development of the offspring.