Cell cycle: mitosis and meiosis

Although this topic will be familiar to most students, there is considerably greater knowledge and understanding required at level 3/KS5 than with earlier study. Students will need to understand both overall principles (for example, why meiosis is a necessary requirement for sexually reproducing organsims) and detail of processes in order to confidently describe, explain and compare the two types of cell division. As with most biology topics, there is a substantial amount of new vocabulary to learn and care is needed over words that sound or are spelt in similar ways.

The topic provides good opportunities for modelling; anything from pipecleaners to socks can be used to model the behaviour of chromosomes and these models can often be animated using stop motion apps. There is also opportunity for practical microscopy skills, with students either preparing their own slides or observing commercially pre-prepared specimens that show both types of cell division.

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Developed by the Royal Institution, these video clips provide a good introduction to the topics of meiosis and mitosis. The mitosis video shows imagery of a real cell dividing with a general overview commentary of chromosome movement. The meiosis video provides a brief discussion on the causes of Down’s syndrome, with the use of modelling to explain the concept of non-disjunction.

The video clips would be best used as an introduction to these topics. The videos could be shown to a class with associated follow up questions that probe their prior knowledge and understanding. The website also lists some TED-Ed lessons where such questions have been added to the base video resource.

From the virtual cell collection, this resource provides a clear animation showing the processes involved with mitosis and is appropriate for level 3/KS5. The animation runs for just over 6 minutes but can be paused at any point. The animation also discusses the cell cycle and clarifies that mitosis is only one part of this overall cycle. A transcript of the audio is provided and a step by step ‘review the animation at your own pace’ features at the bottom of the webpage. The animation would be very useful as a teaching aid in class but could also be turned into an activity whereby students are asked to match up excerpts from the transcript with screenshots taken of the animation and then sequence into the correct order.

From the virtual cell collection, this resource provides a clear animation showing the processes involved with meiosis and is appropriate for level 3/KS5. The animation runs for just over 5 minutes but can be paused at any point. A transcript of the audio is provided and a step by step ‘review the animation at your own pace’ also features at the bottom of the webpage. The animation would be very useful as a teaching aid in class but could also be turned into an activity whereby students are asked to match up excerpts from the transcript with screenshots taken of the animation and then sequence into the correct order.

From the University of Pennsylvania, this resource provides some comprehensive instructions on the use of socks to model chromosome behaviour. Students often struggle to understand how different alleles are segregated during meiosis – this exercise provides a powerful modelling technique whereby different coloured sock pairs can be used to illustrate chromosome homology, replication of DNA, gene loci and segregation of alleles into different gametes. Students will need to have a good understanding of the topic of DNA and an overview understanding of meiosis before this activity is attempted – it is best used to provoke deeper thought and highlight misconceptions that students may harbour.

A good homework activity to consolidate understanding of both mitosis and meiosis is for students to produce their own flipbook animation. There are various pre-prepared diagrams and templates available for this online, but it is a more powerful learning exercise to ask the students to produce their own. A flipbook of around fifteen to twenty pages would be enough to show the key points in the process, but students could add more if they wish. The weblink provides an exemplar video clip of such a flipbook being used to animate the process of mitosis

A classic way of modelling meiosis is through the use of pipecleaners to represent chromosomes. Similar to the ‘sockosomes’ activity listed as part of this resource collection, pipecleaners can be used to illustrate chromosome homology, replication of DNA, gene loci and segregation of alleles into different gametes. Crossing over can also be represented by twisting ‘homologous’ pipecleaners together. The resource provides worksheet instructions with clear photographs and is written for students to use.

From the Association of British Pharmaceutical Industry (ABPI), this resource provides comprehensive notes, diagrams and animations on the topic of cell division, including both mitosis and meiosis. The information presented is appropriate to level 3/KS5 study and is written is a clear and informative way that students would find accessible. The animations can be displayed full screen to use as a teaching aid, but the majority of the content would be best used by students for revision purposes. The end of most sections contain a short quiz that students can use to test their understanding.

This is a resource collection from yourgenome, which provides various fact profiles and diagrams for both mitosis and meiosis. These could be printed and used to supplement student notes or converted into a sequencing activity to use in class. The collection also features various other activities and video animations that relate more broadly to the topics of DNA and genomics.

An article from the University of Birmingham, this resource asks the question: ‘Is the onion root tip experiment relevant to research?’ before then expanding to discuss the work of researchers on meiotic pairing and recombination in plants. The article also features a discussion on the importance of Henrietta Lacks and the resulting HeLa immortal cell line that is used in research to this day. The video clip could be played in class to link a common practical technique to the world of research and the rest of the article could be set as a comprehension task for students to read and respond to follow up questions set by a teacher.

Quality AssuredCategory:SciencePublisher:Science & Plants for Schools (SAPS)

In this practical activity from science and plants for school (SAPS) students stain root tips and examine them for signs of cells dividing by mitosis. Students can either compare two different sources of root tip or two different stains.

For the full investigation, some pre-preparation is required for this practical as students will need to mark root tips 2 days before the actual practical in order to be able to calculate the mitotic index. A video clip of the practical can also be viewed here

It would also be useful to have some bought slides available for students to compare against whist undertaking this practical investigation

The preparation of slides in this practical is both time consuming and challenging, but the practical exercise of identifying real cells in different stages of meiosis is valuable in that it connects theory to practice.

Teachers should be aware that even when slides have been correctly prepared, identifying the stages of cell division in the prepared slides can be difficult, although distinctive parts of cell division such as metaphase should be reasonably easy to spot. It would be advisable to have pre-prepared images that can be displayed on a white board or on a guidance worksheet to guide students as to what to look for. It would also be worth having commercially prepared slides for students to look at in case the practical procedure yields inconclusive results.

Students should be confident about the stages of cell division before attempting this practical activity.

This resource was originally written as a GCSE module, but provides a useful short activity for level 3/KS5 students.

Section 2 of the resource entitled "the gene machine" is the section which has the most relevance for this topic. In particular, teachers should read page 35 and use the student sheet 2.1 on pages 40 and 41.

Most questions on the student sheet should be straightforward for level 3/KS5 students. However, questions 3 and 4 may identify previous misconceptions in relation to the separation on chromosomes as a random process.

Students could work in groups or pairs to complete this activity and then be prepared to present their answers with explanations to the rest of the class who can comment on the answers/explanations given.

Quality AssuredCategory:SciencePublisher:Wellcome Trust

This extensive set of resources is centred around a "Big Picture" issue from the Wellcome Trust focusing on the cell. The magazine itself has a number of interesting articles which could be separated and given out for students to read and review. Articles of particular interest to this topic are Dividing we stand, No limits? and Under development.

As well as the magazine itself, this set of resources includes an interesting video clip on the work of a cytologist involved with cancer research