Content Objective: Explain how meiosis, as a reduction division, produces four haploid nuclei from one diploid nucleus and contributes to genetic variation through mechanisms like random orientation and crossing over. Describe the significance of meiosis in the sexual life cycle, the role of gamete fusion in genetic recombination, and use Down syndrome as a case study of meiotic errors such as non-disjunction.
Language Objective: Use key terms like “diploid,” “haploid,” “bivalents,” and “fertilization” to outline and compare the processes of sexual and asexual reproduction, including the genetic outcomes and adaptive advantages of each.
Syllabus Details:
D2.1.9—Meiosis as a reduction division - "Students should understand the terms “diploid” and “haploid” and how the two divisions of meiosis produce four haploid nuclei from one diploid nucleus. They should also understand the need for meiosis in a sexual life cycle. Students should be able to outline the two rounds of segregation in meiosis."
D2.1.10—Down syndrome and non-disjunction - Use Down syndrome as an example of an error in meiosis.
D2.1.11—Meiosis as a source of variation - "Students should understand how meiosis generates genetic diversity by random orientation of bivalents and by crossing over."
D3.1.1—Differences between sexual and asexual reproduction "Include these relative advantages: asexual reproduction to produce genetically identical offspring by individuals that are adapted to an existing environment, sexual reproduction to produce offspring with new gene combinations and thus variation needed for adaptation to a changed environment."
D3.1.2—Role of meiosis and fusion of gametes in the sexual life cycle -"Students should appreciate that meiosis breaks up parental combinations of alleles, and fusion of gametes produces new combinations. Fusion of gametes is also known as fertilization."
Activity 1 - Meiosis Notes and Variation
A. Strengthen Your Skills
Chromatid Numbers/Chromosome Numbers - Amoeba Sisters - Good if you are confused about chromosome numbers
B. Expand Your Knowledge