Mitosis and meiosis 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 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 our mitosis and meiosis simulations. 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: The parent cell makes a copy of every chromosome in the nucleus, creating two full sets of 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: The chromatids line up at the equator of the cell. The mitotic spindle latches to the centromere of each chromatid pair.
Anaphase: 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.
Telophase: A new nuclear envelope forms around the DNA at each end, creating two new nuclei.
Cytokinesis: The cell splits in the middle to form two daughter cells that are genetically identical to the parent cell.
If you’re having trouble visualizing each step of mitosis or you want some extra practice, create a free account and try our mitosis simulation for a more in-depth and complete understanding. Click the “Take this course now” button to get started.
What is Meiosis?
Meiosis is a special type of cell division that creates gametes (sex cells). In meiosis, one cell with one full set of DNA becomes 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.
Metaphase I, Anaphase I, and Telophase 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.
Cytokinesis: The cell divides in half, creating two cells, each with one full set of
chromosomes.
Prophase II: The spindle begins to form in each cell.
Metaphase II–Anaphase II: Mitosis occurs in the two new cells, dividing the chromatids into new nuclei.
Telophase II and Cytokinesis: A new nuclear envelope forms around the chromosomes at each of the cell, and the cells divide to create a total of four gametes.
If you would like a more detailed explanation, try the meiosis simulation to build a stronger foundation.
5 key differences
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
Asexual
Results in 2 cells
Daughter cells are the same cell type as parent cells
Daughter cells are genetically identical
Daughter cells each have a full set of chromosomes (in humans, 46)
Meiosis
Sexual
Results in 4 cells
Daughter cells are gametes
Daughter cells are genetically unique
Daughter cells each have half a set of chromosomes (in humans, 23)
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.
Draw: Drawing both processes out on paper is a good practice exercise to deepen your understanding of mitosis and meiosis. Don’t forget to label the phases, and write a brief description of what is occurring in each.
Mitosis and Meiosis Simulations: 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?
Practice: Act out meiosis and mitosis using different colors of pipe cleaners as the DNA and string as the spindle.