Download Suggested time: 45 minutes Summary of Key Learning

topic: Cells
activity: Mitosis
Students explore the eukaryotic cell cycle and mitosis using this hands-on interactive!
Suggested time: 45 minutes
Summary of Key Learning Points
Students:
- describe the main phases in the cell cycle
- learn the names of the phases in mitosis
- discover the major events occurring in each phase in mitosis
- identify examples of real cells undergoing the different phases of mitosis
The cell cycle
10 minutes
Selecting the cell brings students to a view showing a cut-away of a generic animal cell and a dynamic cell
cycle ‘counter’. Encourage students to play the animation several times through. Ask them to estimate from
the counter what percentage of time each cell spends in interphase (answer = around 90%).
Talking points:
Why do the cells need to get bigger before dividing? (Answer = because otherwise the cells would get
smaller and smaller with each division)
Why does the DNA need to copy itself during S phase? (Answer = because each daughter cell must contain
the same genetic information as the parent cell)
What is the difference between chromatin and a chromosome? (Chromatin is DNA in its unwound form. It is
not fully unwound however, but is wrapped around histones. A chromosome is the chromatin wound up into
an even more condensed form. These condensed forms are necessary to pack the 2m of DNA in every cell
into the tiny nucleus!)
What stimulates cells to divide? (i.e. When are new cells needed? Answer = they are needed for growth and
repair/replacement)
Cell cycle
5 minutes
This page gives students a close-up view of the cell cycle diagram and also asks them to think about how
long the process might take. Obviously this depends on the cell, so the example given is a human skin cell.
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topic: Cells
activity: Mitosis
Answer: 24 hours (Inquiry point 1)
Examples of time taken for other cells to go through the cell cycle:
Embryo = 30 minutes
Yeast = 2 hours
Intestinal wall cells = 12 hours
Liver cells = 1 year (for a healthy, fully-formed liver)
Mitosis - interactive
15 minutes
The mitosis interactive allows students to participate in the mitosis process. Make sure they think about the
actions they are doing. For example, when they make a circular motion to condense the chromatin, get them
to verbally explain what it means. There are many talking points along this interactive journey!
Talking points:
What are centrioles and what do they do? (Answer = tubular structures that help to form and organise the
spindle)
How do the spindle fibres attach to the chromosomes? (Answer = they attach to the kinetochores)
How is a cell equator like the Earth’s equator? (Answer = it is an imaginary line through the centre of the
cell)
In which stages of the process does the nuclear membrane disappear and reappear? (Answer = breaks up
during prometaphase, reforms during telophase)
Are the two daughter cells formed EXACTLY the same as the parent cell? (Answer = no! They are
genetically identical but may differ in the number of other cell components such as mitochondria or
ribosomes.)
Inquiry points 2—7 are gained by performing the right actions on the interactive.
Photo challenge
5 minutes
The slide is of onion root tip cells. The root tip is a good place to view mitosis because this is where the plant
is always growing. Five of the cells in the image of an onion root tip are movable. Placing them in the correct
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topic: Cells
activity: Mitosis
order should give the answer below. Remind students that the only reason we can see the DNA is because it
is wound up into chromosomes. At the end of mitosis, the DNA unwinds into chromatin and will no longer be
visible through a microscope.
Answers:
(Inquiry point 8)
Interphase/G2 (Inquiry point 9)
Cytokinesis (Inquiry point 10)
Suggested completion levels
Basic – Inquiry point goal = 7
Students at this level will: identify interphase, mitosis and cytokinesis as parts of the cell cycle; describe in
simple terms what happens during mitosis.
Core – Inquiry point goal = 9
Students at this level will: identify all parts of the cell cycle; understand the timing of the cell cycle in human
skin cells; explain what happens during each stage of mitosis.
Advanced – Inquiry point goal = 10
Students at this level will: identify all parts of the cell cycle and calculate the percentage of time spent in
each stage; understand that different cells take different amounts of time to go through the cell cycle; explain
in detail what happens during each stage of mitosis; recognise real cells undergoing the different stages of
mitosis.
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