Video Transcript
A human somatic, body, cell contains 46 chromosomes. How many chromosomes does a gamete, sex cell, contain? (A) 12 chromosomes, (B) 46 chromosomes, (C) 92 chromosomes, (D) seven chromosomes,
(E) 23 chromosomes.
In order to answer this question, we need to remember what gametes are and how they
differ from somatic cells. This will help us recall the difference in the number of chromosomes between these
two cells.
Most cells in the human body are called somatic cells, and they make up every organ
and tissue apart from the sex cells which are located in the gonads. Human somatic cells typically contain 46 chromosomes and are diploid cells because
they have a full set of genetic material having received DNA from both biological
parents. The prefix diplo- in the word diploid comes from Greek and means double. This refers to the two copies of each chromosome in diploid cells.
As mentioned, in contrast to somatic cells, sex cells, which are also known as
gametes, are very important for the process of sexual reproduction. In human females, the gametes are called ova, or egg cells, while in human males, the
gametes are called sperm cells. Gametes are haploid cells. The prefix haplo- in the word haploid comes from the Greek word for single and refers
to the single copy of each chromosome found in haploid cells. So, haploid cells contain half the number of chromosomes of somatic cells. Therefore, if we divide the 46 chromosomes we know exist in diploid somatic cells by
two, we get 23. This means each gamete contains 23 chromosomes.
In sexual reproduction, during fertilization, an egg and a sperm cell join to form a
zygote. The zygote has 46 chromosomes. Half of the chromosomes in the zygote come from the egg cell and the other half come
from the sperm cell. So, to review, since each gamete is a haploid cell, they contain half the genetic
material of somatic, diploid cells, which is typically 23 chromosomes.
With this information, we are able to answer the question. A gamete, or sex cell, contains 23 chromosomes.
