有丝分裂和减数分裂are two of the most commonly misunderstood topics on the AP Biology exam. This complete review guide will give you a crash course in mitosis and meiosis stages, and highlight the key differences between the mitosis and meiosis. It will also teach you how to study through suggested review exercises.
If you are learning for the first time, skip the written study guide and go straight to ourmitosisandmeiosissimulations. The simulations will give you a clear and detailed understanding of both processes in an engaging format. Otherwise, read on to start the review!

What is mitosis?

Mitosis happens when a cell duplicates. The process starts with one cell and one set of chromosomes, and ends with two cells and two sets of chromosomes. Mitosis is divided into several phases. Here’s how it works:

Interphase:父细胞会复制细胞核中的每个染色体，从而产生两个完整的DNA。

Prophase:The chromosomes condense into chromatids. A centromere links each chromatid to its copy, making the linked pairs look like X’s. The nuclear envelope breaks down, and the mitotic spindle begins to form.

Metaphase:细胞的染色单体在赤道。The mitotic spindle latches to the centromere of each chromatid pair.

后期：The spindle pulls the chromatids and their copies in opposing directions, breaking the link and gathering one complete set of chromosomes at each end of the cell.

末期：两端的DNA周围形成一个新的核包膜，形成两个新的核。

细胞因子：细胞在中间分裂，形成两个与母细胞相同的子细胞。

什么是减数分裂？

如果您难以可视化每个步骤有丝分裂或想要一些额外的练习，请创建一个免费帐户和尝试我们的有丝分裂模拟为了更深入而完整的理解。单击“立即获取此课程”按钮以开始。

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减数分裂is a special type of cell division that creates gametes (sex cells). In meiosis, one cell with one full set of DNA becomes with four gametes. Gametes are special because they only have one half of the chromosomes of a normal cell. Here’s how it works:

Prophase I:Each chromosome is copied and condenses to form linked chromatids. Homologous pairs (each linked to their own copy) exchange DNA through crossing over. The spindle begins to form.If you are not familiar with homologous pairs and crossing over, skip the rest of this description and go straight to the video at the end.
中期I，Ahophase I和末期I：The homologous pairs line up at the equator, and are separated by the spindle. They group at opposite ends of the cell, where new nuclei form.
细胞因子：细胞分为一半，形成两个细胞，每个细胞都有一组完整的染色体。 预言II：The spindle begins to form in each cell.
中期II – Anophase II：Mitosis occurs in the two new cells, dividing the chromatids into new nuclei.
末期II和细胞因子：A new nuclear envelope forms around the chromosomes at each of the cell, and the cells divide to create a total of four gametes.

如果您想要更详细的解释，请尝试meiosis simulationto build a stronger foundation.

5个关键差异

The best way to remember mitosis and meiosis is to understand the ways in which they are different. If you can remember the following five conceptual differences between mitosis and meiosis, you’ll be all set for the exam.

	Mitosis	减数分裂
1	无性	Sexual
2	结果是2个细胞	结果是4cells
3	子细胞是same cell typeas the parent cell	Daughter cells aregametes
4	Daughter cells aregenetically identical	Daughter cells are遗传独特
5	Daughter cells each havea full set of chromosomes（在人类中，46）	Daughter cells each have a一半染色体（在人类中，23）

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Review tips

Memorizing terms and steps is not helpful for the AP exam. There is too much content to rely on rote memorization. The best way to prepare yourself for the exam is to understand the fundamentals behind each topic, and then see what connections you can make. The more variety incorporated into your practice, the easier the AP exam will be.

• 画：在纸上绘制这两个过程是一种很好的练习，可以加深您对有丝分裂和减数分裂的理解。不要忘记标记这些阶段，并简要描述每个阶段。
• Mitosisand减数分裂模拟华体会赞助ac米兰：You can also use our Mitosis and Meiosis simulations as an effective review tool to review the material and to quiz yourself. If you think you have a good grasp of the concepts, do the simulations and see if you can predict what happens next.
• Apply:Create scenarios in which something goes wrong with each of the phases, and predict what the end result of the failed process would be. For example: What would happen if a chromatid and its copy didn’t separate during Anaphase II of meiosis? What would the cells look like at the end? What would the long term effects be?
• 实践：用不同颜色的管道清洁剂作为DNA和弦作为主轴进行减数分裂和有丝分裂。Read more about this activity。