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Question Video: Examining the Gamete Responsible for Determining Sex Biology

Which gamete is responsible for determining the sex of a fetus?

02:53

Video Transcript

Which gamete is responsible for determining the sex of a fetus?

This question asks about the gamete responsible for sex determination. Can you remember what a gamete is? Gametes, which are sometimes referred to as reproductive or sex cells, refers to haploid cells that contain half the genetic material compared to other typical body cells. In humans, most of the body cells are referred to as diploid and contain 46 chromosomes, while gametes are haploid and contain half this number, which is 23 chromosomes.

A female gamete is called an ovum or egg cell, and a male gamete is called a sperm cell. In each gamete, 22 of the 23 chromosomes are referred to as autosomes. Autosomes are chromosomes that can be arranged into homologous pairs when gametes are joined. This is because the other gamete will contribute an autosome that is similar in structure and genetic contents. These chromosomes are named based on size from one to 22. The 23rd chromosome in each gamete is referred to as the sex chromosome.

Can you remember the two types of sex chromosomes that exist in humans? Sex chromosomes can either be X or Y. And these contain specific genes for the development of sex characteristics. You might have learned that a pair of X chromosomes, XX, usually results in the development of a biological female. On the other hand, XY results in a biological male. This is because the Y chromosome contains genes for male sex characteristics.

During the process of gamete formation in males and females, the genetic material in a diploid cell is split. Sex chromosomes are split just as we would expect, one sex chromosome per gamete. Because biological females only contain X chromosomes, all of their egg cells will contain an X chromosome as well, in addition to the 22 autosomes. On the other hand, we would expect biological males to produce gametes with either an X or a Y chromosome. Therefore, the sperm cell is the gamete responsible for sex determination, since it can either contribute an X or a Y chromosome to the developing offspring, making it either biologically male or biologically female.

Now that we have reviewed sex chromosomes and how they differ among male and female gametes, we are able to respond correctly to our question. The question asks us, which gamete is responsible for determining the sex of a fetus? And we know that the correct answer is the sperm.

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