At the End of This Module You Should Be Able to Do the Following

BIOLOGY SEMESTER ONE UNIT 13

UNIT 13: MEIOSIS

In this module you will investigate a second type of cell division called meiosis. In this process of cell division, the end product is not two identical clone cells, but four daughter cells that are genetically distinct from one another. The resulting daughter cells have a full set of single chromosomes (a total of 23 chromosomes in humans). This type of cell division results specifically in gametes (sex cells) such as eggs and sperm in most animals, or egg and pollen in most plants. Meiosis is essential for sexual reproduction.

LEARNING OBJECTIVES

At the end of this module you should be able to do the following:

1. Distinguish between the following terms: somatic cell and gamete; autosome and sex chromosomes; haploid and diploid.

2. Describe the events that characterize each phase of meiosis.

3. Compare and contrast meiosis and mitosis, including the ultimate purpose of each.

4. Distinguish between asexual and sexual reproduction and outline the benefits of each.

5. Describe alternation of generation in animals, plants and fungi.

CHECK LIST

 Read Chapter 13 of Campbell and Reece’s Biology, 9th Ed.

 As you are reading, address each of the learning objectives listed above.

 Watch the video clip “Meiosis,” and complete the meiosis practice worksheet.

 Make flash cards for the terminology list provided (optional). This will be beneficial for studying for the midterm and final exams later in the semester.

 You may be able to review the PowerPoint Lecture and other resources for this unit. Refer to your instructor’s notes for more details.

 For extra practice try the Self Quiz or Practice Test on the Mastering Biology Website. To log onto the website, use the access code provided in your textbook. You will also find other resources, such as downloadable MP3 tutorials for each chapter, a glossary, and an electronic copy of your text—you can catch up on your reading anywhere!

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KEY TERMS allele gene sex chromosome alternation of generations genetics sexual reproduction asexual reproduction haploid cell spore autosome heredity sporophyte clone homologous chromosomes synapsis crossing over karyotype variation diploid cell life cycle zygote gametophyte recombinant chromosome

ROOT WORDS TO KNOW1 a- = not or without (asexual: type of reproduction not involving fertilization) -apsis = juncture (synapsis: the pairing of replicated homologous chromosomes during prophase I of meiosis) auto- = self (autosome: the chromosomes that do not determine gender) chiasm- = marked crosswise (chiasma: the X-shaped microscopically visible region representing homologous chromosomes that have exchanged genetic material through crossing over during meiosis) di- = two (diploid: cells that contain two homologous sets of chromosomes) fertil- = fruitful (fertilization: process of fusion of a haploid sperm and a haploid egg cell) haplo- = single (haploid: cells that contain only one chromosome of each homologous pair) homo- = like (homologous: like chromosomes that form a pair) karyo- = nucleus (karyotype: a display of the chromosomes of a cell) meio- = less (meiosis: a variation of cell division that yields daughter cells with half as many chromosomes as the parent cell) soma- = body (somatic: body cells with 46 chromosomes in humans) sporo- = a seed; -phyte = a plant (sporophyte: the multicellular diploid form in organisms undergoing alternation of generations that results from a union of gametes and that meiotically produces haploid spores that grow into the gametophyte generation) syn- = together; gam- = marriage (syngamy: the process of cellular union during fertilization)

SOURCES 1 (Pearson Education, 2010)

Creative Commons Attribution 3.0 Unported License 2 BIOLOGY SEMESTER ONE UNIT 13 Campbell, N. A. (2008). Biology, Eighth Edition. San Francisco: Pearson, Benjamin Cummings.

Pearson Education. (2010). Retrieved 2010, from Mastering Biology : http://session.masteringbiology.com

NANSLO Biology Core Units and Laboratory Experiments by the North American Network of Science Labs Online, a collaboration between WICHE, CCCS, and BCcampus is licensed under a Creative Commons Attribution 3.0 Unported License; based on a work at rwsl.nic.bc.ca. Funded by a grant from EDUCAUSE through the Next Generation Learning Challenges.

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