Mitosis and Meiosis

Explore the two types of cell division, mitosis and meiosis, and the differences between them.

  • Credit: Tim Mitchell

Introduction

We have developed a series of clips to explore the Life Fantastic with your students. The pages are intended for use as a prompt to help you prepare when exploring these topics in lessons. Teachers have told us that the videos and questions best suit being used as a topic introduction.

On this page you will find an overview of the topic covered by the clips, a brief summary of each clip, related questions and how the topic links to the curriculum.  This is one of eight available resources on developmental biology. For more topics see the teaching resources list.

Overview

Topics in the videos

  • Review that DNA is packaged into chromosomes and that these are found in the nucleus of the cell
  • Understand that during cell division, chromosomes are assorted into daughter cells
  • Understand that during mitosis, chromosomes are replicated and assorted identically into each daughter cell
  • See how mitosis contributes to the growth of an organism
  • Understand that during mitosis chromosomes are randomly assorted into daughter cells and that this is one of the ways that the daughter cells are not genetically identical
  • Describe the key differences between mitosis and meiosis
  • See one example of a genetic disease which occurs due to an error in meiosis

The material in this resource is supported by video clips from the CHRISTMAS LECTURES 2013.

Curriculum links

This resource is suitable for Key Stages 3 and 4 and AS/A2 level. Full curriculum links are given at the bottom of the page.

Clip 1 - Mitosis in live cells

Alison Woollard explains this process of mitosis using a video of a real cell. The chromosomes, seen in red on the video, first replicate themselves (difficult to see in this video), then get divided precisely into two sets and next move to opposite sides of the dividing cell, into the daughter cells. Finally, the cell membrane (blue) forms between the two cells and the two daughter cells are formed.

Running Time: 1 min 25 secs

Summary questions

  • What are long molecules of DNA called? (Chromosomes, 0:24)
  • How many pairs do we have in each human cell? (23,  0:27)
  • How many cells are produced by the division? (Two daughters, 0:48)

Background questions

  • What is the process of cell division that is featured in the video clip called? (Mitosis)
  • What are the two types of cell division? (Mitosis and meiosis)
  • How many chromosomes does a cell have before mitosis? How many does each cell have after mitosis? (In a human, 46 before and 46 after)
  • What is the name of the cells that are generated by mitosis? (Daughter)
  • Describe the main phases of mitosis

Suggested expansions and links

  • For an additional example of mitosis watch Life Fantastic Where do I come from? to see the first hour of a nematode’s embryonic development. This early stage of embryonic development exemplifies how mitosis contributes to an organism’s growth.
  • The content of this resource sits alongside with the teaching resource ‘DNA replication and mutation’ which analyses the process of DNA replication that occurs during the cell cycle.

Clip 2 - Meiosis and what can go wrong

In the 21st of the Chromosome videos, Yan Wong explores the process of meiosis. DNA is organised into chromosomes; humans have 23 pairs – 46 altogether. Accidentally duplicating copies of the DNA can cause problems later on, and this is what happens in conditions such as Down’s syndrome. Typically Down’s syndrome has an extra copy of chromosome 21, a problem which originates during the formation of sperm and eggs in meiosis. Using coloured blocks as models for chromosomes, Yan shows how the 46 chromosomes in the dividing cell are assorted during meiosis into the daughter cells, each with 23 chromosomes. Yan demonstrates crossing over between the chromosomes and illustrates how each of the four daughters is genetically different. In the final part of the clip, Yan shows what goes wrong in conditions like Down’s syndrome: the chromosomes don’t separate properly during meiosis and one sex cell has one too many chromosomes.

Running Time: 4 min 2 secs

Summary questions

  • How many chromosomes do humans have in each cell? (23 pairs and 46 altogether, 0:27)
  • Which chromosome is duplicated in Down’s syndrome? (21, 0:58)
  • What is the name of the form of cell division in the video? (Meiosis, 1:11)
  • How many chromosomes do humans have in the sperm and eggs, the gametes? (23, 1:20)
  • What happens during crossing over? (Genetic material is exchanged, 2:01)

Discussion questions and points

  • Are the four daughter cells formed during meiosis genetically identical or different? (Different, 2:22) How is this useful during evolution?
  • What is the scientific name for a human cell with all 46 chromosomes? 23 chromosomes? (46 – Diploid; 23 – Haploid)
  • At which stages during meiosis is variation generated? (Random assortment, crossing over)
  • What is special about the form of cell division featured in the video? (Each cell is unique and has half the number of chromosomes to the original cell)

Curriculum links

KS3

Although this resource explores topics which are beyond the KS3 curriculum, the explanation of how gametes form in clip 2 provides an extension to the requirements found in ‘Structure and function of living organisms: Reproduction’.

KS4

The clips describe the processes of mitosis and meiosis appropriate to the requirements of Edexcel GCSE Biology 2BI01/Additional Science 2SA01 Unit B2 Topic 1 ‘The building blocks of cells’ 1.13, 14, 16; AQA GCSE Biology 4401/Additional Science 4408 Unit 2: Biology 2 B2.7.1 ‘Cell division’ and Higher Tier students (when introducing the 4 genetically different cells formed by meiosis); OCR GCSE Biology A J243/Additional Science A J242 Unit A162 Module 5 ‘How do organisms develop?’ B5.1 3-6 and ‘How does an organism produce new cells?’ B5.2; and in the discussion of genetic disorders in AQA GCSE Science B 4450 Unit 2: My Family and Home 3.4.1.3 ‘Human Inheritance and genetic disorders’.

AS/A2

The resource explores the mechanisms of mitosis and meiosis. Mitosis is shown using a clip of a live cell division which corresponds to the requirements found in AQA GCE Biology AS 1411 Unit 2 BIOL2 ‘The variety of living organisms’ section 3.2.5; OCR GCE Biology AS Unit F211 Module 1 ‘Cells’ section 1.1.3. Meiosis is described as a separate process, resulting in non-identical daughters and leading to variation in populations and species as required in AQA GCE Biology AS 1411 Unit 2 BIOL2 ‘The variety of living organisms’ section 3.2.2; OCR GCE Biology AS Unit F211 Module 1 ‘Cells’ section 1.1.3 and A2 Unit F215 Module 1 ‘Cellular control and variation’ 5.1.2.

Watch the full lectures

View the full CHRISTMAS LECTURES, Life Fantastic, along with behind the scenes footage, and related content, at the Ri Channel (www.richannel.org).