Download Cell division

topic: Cells
activity: Cell division
Students learn about the different types of cell division in prokaryotic and eukaryotic organisms through
videos and animations.
Suggested time: 45 minutes
Summary of Key Learning Points
Students:
- recognise that all cells come from pre-existing cells
- understand that bacteria reproduce by binary fission
- observe that yeast reproduce by budding
- discover that mitosis is needed for growth and repair
- find out that meiosis enables sexual reproduction to occur
Cell divisionÂ
5 minutes
The activity opens on a view of hairy, human skin as the activity centres around the different types of cells
which can be present on the skin and their cell division. Students are first asked to choose how many cells
we are made of.
Answer: One hundred trillion (Inquiry point 1)
Following this question they are asked how we grow.
Answer: The number of cells increases (Inquiry point 2)
Although this answer is mostly correct, there is also a bit of the other happening (existing cells getting
bigger). This is particularly the case with fat cells, as the number of these is set in childhood.
Making new cells
5 minutes
The view zooms to a close up of the skin with some yeast and bacteria visible. Remind students that our skin
is covered in microbes. In fact, we have a greater number of microbes on us and in us than we have cells in
our body! Skin cells are constantly shed and students are asked where new cells come from.
Answer: New skin cells are generated in the epidermis (Inquiry point 3)
© IntoScience 2014. This sheet may be reproduced for classroom use
Page 1/4
topic: Cells
activity: Cell division
The feedback reminds students that one of the tenets of cell theory is that all cells come from pre-existing
cells.
Talking point: What are the other tenets of cell theory? Who was it that first proposed the fact that all cells
come from pre-existing cells?
Binary fission
10 minutes
Golden staph is a bacteria present on our skin. Students watch a time-lapse video of this bacterium
reproducing.
Answer: The video shows golden staph bacteria dividing to make more bacteria.
Students will probably need to be helped through the information on binary fission. Make sure they note what
the terms 'unicellular' and 'prokaryotic' mean. The animation shows that the DNA attached to the cell
membrane replicates. Each copy is attached at a separate point so that when the cell grows bigger the two
copies are separated. A furrow appears and then the cell splits into two. Show students that prokaryotes do
not have a membrane-bound nucleus and so they are viewed as simpler organisms than eukaryotes.
Students are then asked to classify the purpose of the process.
Answer: Asexual reproduction (Inquiry point 4)
Talking point: Golden staph is always present on our skin and yet it is causing havoc in hospitals. Why is
this? (Answer: the antibiotic resistant strains are getting into wounds and producing infections that cannot be
eliminated.)
Budding
5 minutes
Yeast is a type of fungi. Explain to students that it is not the only type and some fungi also grow hyphae. The
time-lapse video shows yeast replicating by budding. Emphasis the term 'eukaryote' and recall that this
means the organism has a membrane-bound nucleus. Students are asked to classify the purpose of this
process.
Answer: Asexual reproduction (Inquiry point 5)
Extension: Have students research different types of fungi and find out what types of cell division they use
to reproduce.
Â
Mitosis
© IntoScience 2014. This sheet may be reproduced for classroom use
Page 2/4
topic: Cells
activity: Cell division
10 minutes
The process of mitosis is only briefly introduced here and so the stages are not outlined. This could be done
as an extension. The animation of the epidermis shows new cells being formed in the lower layer. These
cells gradually flatten as they rise up through the epidermis and are eventually shed from the top.
Example answer: The animation shows new cells being formed by cell division in the lower epidermis.
(Inquiry point 6)
After this, students watch a video of a human cell undergoing mitosis. Tell them that the wormy-looking
things are the chromosomes. They should use and understand they terms 'parent cell' and 'daughter cells'.
Students choose where in the body mitosis takes place.
Answers: Your liver is damaged, your hair grows, an embryo turns into a baby. (Inquiry point 7)
Meiosis (Explore this)
5 minutes
The feedback from the previous question leads into the meiosis page, since the eggs and sperm being made
were not an example of mitosis. The Science extra on cancer explains that cancer is uncontrolled mitosis.
Extension: Have students research the steps in mitosis and draw a diagram to show these steps, or they
could produce a poster using confectionery worms as chromosomes.
The meiosis page starts with an animation of a sperm meeting an egg. Emphasise to students the size of the
egg and why it is so big (contains nutrients to help the zygote turn into a blastocyst). Talk students through
the information and explain why sex cells only have half the normal chromosome number (because they
combine to produce one cell with the correct chromosome number). Students are asked to classify the
purpose of the process.
Answer: Sexual reproduction (Inquiry point 8)
Class activity: Discuss the advantages offered by sexual reproduction over asexual reproduction (greater
genetic variation means that the species will likely have greater longevity as no single factor is likely to wipe
the whole population out at once).
Cell division snapshot
5 minutes
The activity finishes with a summary where students must choose the correct number of parent cells,
daughter cells, the purpose of each process and which type of organism will undergo that process.
© IntoScience 2014. This sheet may be reproduced for classroom use
Page 3/4
topic: Cells
activity: Cell division
Answers:
Mitosis: 1 parent cell, 2 daughter cells, growth and repair, eukaryote (Inquiry point 9)
Meiosis: 1 parent cell, 4 daughter cells, sexual reproduction, eukaryote (Inquiry point 10)
Budding: 1 parent cell, 2 daughter cells, asexual reproduction, eukaryote (Inquiry point 11)
Binary fission: 1 parent cell, 2 daughter cells, asexual reproduction, prokaryote (Inquiry point 12)
Suggested completion levels
Basic - Inquiry point goal = 6
Students at this level will: recognise that all cells come from pre-existing cells; understand that different types
of cell division are needed for different purposes.
Core - Inquiry point goal = 9
Students at this level will: understand that all cells come from pre-existing cells; identify the different types of
cell division, where they occur and their functions; state the number of daughter cells produced in each cell
division process.
Advanced - Inquiry point goal = 12
Students at this level will: explain that all cells come from pre-existing cells; identify the different types of cell
division, where they occur and their functions; state the number of daughter cells produced in each cell
division process; account for the different number of chromosomes in cells produced by mitosis and meiosis
in the same organism.
© IntoScience 2014. This sheet may be reproduced for classroom use
Powered by TCPDF (www.tcpdf.org)
Page 4/4