Chromosomes, located in the nuclei of cells, serve as DNA storage. Each chromosome contains proteins called histones, around which the DNA is neatly coiled—like an incredibly long strand of thread wound around a spool.
There are 46 “DNA spools” per human cell, organized into 23 pairs. Of each chromosome pair, one is inherited from the biological mother, the other from the biological father. Organisms with two complete sets of chromosomes, one inherited from each parent, are known as diploid.
Human egg and sperm cells are the exception to the 46-chromosomes-per-cell rule. These cells are haploid; they each contain just one set of chromosomes. When a sperm and egg combine, the two sets of 23 chromosomes come together, enabling the offspring to inherit traits from both parents.
In regard to its ________, a chromosome is similar to a spool of thread.
A
color
B
structure
C
chemical composition
D
length