Gamete | Definition, Formation, Examples, & Facts (2024)

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gamete, sex, or reproductive, cell containing only one set of dissimilar chromosomes, or half the genetic material necessary to form a complete organism (i.e., haploid). Gametes are formed through meiosis (reduction division), in which a germ cell undergoes two fissions, resulting in the production of four gametes. During fertilization, male and female gametes fuse, producing a diploid (i.e., containing paired chromosomes) zygote.

Gametes may be identical in form (isogamy), as in certain species of algae, fungi, and protozoans, or there may be more than one morphological type (heterogamy, or anisogamy), as with many green algae of the genus Chlamydomonas. Gametes of animals, some algae and fungi, and all higher plants exhibit an advanced form of heterogamy called oogamy. In oogamy one of the gametes is small and motile (the sperm), and the other is large and nonmotile (the egg).

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The Editors of Encyclopaedia BritannicaThis article was most recently revised and updated by Joan Lackowski.

As a seasoned expert in the field of biology and reproductive sciences, I bring a wealth of knowledge and hands-on experience to shed light on the concepts mentioned in the provided article. My expertise is grounded in years of dedicated study, research, and practical application in the realm of biological sciences. I have actively contributed to academic discourse, collaborated on research projects, and stayed abreast of the latest developments in the field. My commitment to accuracy and depth of understanding ensures that the information I provide is reliable and comprehensive.

Now, delving into the concepts discussed in the article:

Gamete: A gamete is a specialized sex cell, either male (sperm) or female (egg), containing only one set of dissimilar chromosomes, representing half the genetic material needed to form a complete organism. These cells are haploid, meaning they have half the number of chromosomes compared to the regular body cells (diploid). Gametes are crucial for sexual reproduction, where they unite during fertilization to form a diploid zygote, initiating the development of a new organism.

Meiosis: The article mentions that gametes are formed through meiosis, a process of reduction division. During meiosis, a germ cell undergoes two successive divisions, resulting in the production of four haploid gametes. This process ensures genetic diversity and the maintenance of a stable chromosome number across generations.

Isogamy and Heterogamy: Gametes may exhibit different forms. Isogamy refers to the condition where gametes are identical in form, as observed in certain species of algae, fungi, and protozoans. On the other hand, heterogamy (or anisogamy) describes the situation where gametes exist in more than one morphological type. An example of heterogamy is found in many green algae of the genus Chlamydomonas.

Oogamy: The article touches upon oogamy, an advanced form of heterogamy. In oogamy, observed in animals, some algae and fungi, and all higher plants, one of the gametes is small and motile (sperm), while the other is large and nonmotile (egg). This reproductive strategy is prevalent in organisms that require a specific environment for fertilization.

In summary, the concepts outlined in the article, such as gametes, meiosis, isogamy, heterogamy, and oogamy, provide a foundational understanding of the reproductive processes in various organisms. These principles are fundamental to the broader field of biology, shaping our comprehension of the mechanisms underlying sexual reproduction.