Crossing Over in Prophase I. Homologous chromosomes pair up. Nonsister chromatids exchange segments in a process called crossing over. Crossing over leads to genetic recombination. Metaphase I Alignments. During metaphase I, homologous chromosomes randomly line up at the spindle equator.
From Gametes To Offspring. Gamete Formation in Plants. Events such as spore formation may occur between meiosis and gamete formation. Haploid spores germinate into haploid gamete-producing bodies. Gamete-producing bodies and spore-producing bodies develop during the life cycle of plants.
Gamete Formation in Animals. In males, meiosis and gamete formation are called spermatogenesis. Spermatids change in form; each develops a tail to become a mature sperm.
In some cases, these new combinations may make an organism more or less fit able to survive and reproduce , thus providing the raw material for natural selection. Genetic variation is important in allowing a population to adapt via natural selection and thus survive in the long term. Improve this page Learn More. Skip to main content. Module 8: Cell Division. Search for:. Genetic Variation in Meiosis Learning Outcomes Understand how meiosis contributes to genetic diversity.
Try It. This process is known as fertilisation. Gametes contain half the number of chromosomes of all other cells in the organism. This means they are haploid. When the male and female gametes combine in fertilisation they create an embryo with the full complement of chromosomes diploid. Cells which are diploid have two sets of chromosomes - for most organisms this means the cells have one set of chromosomes from their mother and one set from their father. The gametes in animals are sperm male and eggs female.
The gametes in flowering plants are pollen male and ovules female. The offspring produced in sexual reproduction are genetically different to each other and to their parents.
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