Sex Cells

Lesson Plan - Get It!

Audio:

You may look similar to your siblings or cousins, but you have unique features that make you, you!

This occurs because you are a blend of the genetic material from each of your parents. That genetic material, or DNA, is stored in every cell in your body.

Somatic cells, or body cells, hold 23 pairs of DNA organized in chromosomes.

Somatic cells include each type of cell found in the human body: blood, nerve, skin, and muscle.

Humans also have sex cells that hold half the number of chromosomes. Females have XX chromosomes, while males have XY chromosomes. These sex chromosomes pass on important genetic material to offspring.

Sex cells are ovum, or eggs, found in females, and sperm, found in males.

Human eggs are much larger than sperm. They are round and are produced in the ovaries during the process of oogenesis.

Oogenesis, or egg development, occurs when the cell divides unequally during cell division processes in meiosis. Meiosis is where one cell divides into four cells with half the genetic material.

One egg and three polar bodies are formed during this process. Polar bodies are smaller cells that do not mature.

Egg cells carry one X chromosome to contribute to the offspring. This process occurs before the female infant is born, and the eggs mature during puberty, triggered by the production of sex hormones.

Females are born with a limited number of eggs held in the ovary, ready to be released one at a time for ovulation during the menstrual cycle.

Male sex cells are called sperm. Sperm are motile, meaning they can move independently. They swim with a flagellum or a tail.

Sperm cells also have a head region of proteins penetrating an ovum during sexual fertilization.

Sperm are produced during spermatogenesis. It is a process similar to ovum development but results in four equal-sized sperm cells.

Males produce millions of sperm stored in the testes each month.

Sperm can either carry an X or a Y chromosome, determining the sex of offspring from sexual fertilization.

Sex cells are a critical part of human reproduction. They ensure that genetic information is passed from parents to offspring but allow for a blend so that we are not clones of our parents!

Females have large ovums produced during oogenesis and stored in the ovary, while males use spermatogenesis to produce millions of sperm.

Each sex cell has a unique structure: eggs are round, and sperm can move independently.

• Why do you think it is important for sex cells to contain half the genetic information of a body cell?
• How might a sperm's structure influence its function?

In the Got It? section of the lesson, you will learn more about scientific vocabulary associated with sex cells.