Summary
Two rounds of division that halve chromosome number to form genetically varied haploid gametes.
In depth
Meiosis I separates homologous chromosomes (reductional) and meiosis II separates sister chromatids (like mitosis). Two sources of variation exist: crossing over in prophase I and independent assortment in metaphase I; humans can make 2^23 chromosome combinations before crossing over.
Meiosis keeps chromosome number constant across generations, since fertilisation restores diploid number. Errors cause aneuploidy such as Down syndrome.
Frequently asked questions
What is Meiosis?
Two rounds of division that halve chromosome number to form genetically varied haploid gametes.
Which area of biology covers Meiosis, and how advanced is it?
Meiosis is one of the 52 topics in Cell Biology. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Mitosis, Cell Cycle, Cell Cycle Checkpoints.
Can you give an example of Meiosis?
In women, meiosis begins before birth and is arrested until ovulation, one reason maternal age raises the risk of errors.
What should I learn before Meiosis?
Work through the Beginner topics in Cell Biology first, such as Cell Theory, Prokaryotic Cell, Eukaryotic Cell, then return to Meiosis. Intermediate topics assume the Beginner vocabulary.
What topics are related to Meiosis?
The closest topics to Meiosis are Mitosis, Cell Cycle, Cell Cycle Checkpoints, Nucleus. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Meiosis?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Meiosis. To practise the whole of Cell Biology, use the Cell Biology quiz.
How is Meiosis different from Mitosis?
Meiosis: Two rounds of division that halve chromosome number to form genetically varied haploid gametes. Mitosis: Nuclear division that produces two genetically identical daughter nuclei with the same chromosome number as the parent. Read both side by side and note what each one explains.
How should I study Meiosis step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Mitosis and explain the difference aloud. Finally, take the Cell Biology quiz and come back to this page for any question you miss.