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Cell Division
What you should know by the end of this booklet:
Cells are the basic units of life.
We use stain when looking at cells under a microscope to see the
cell contents more clearly.
Animal cells have a nucleus, cytoplasm and a cell membrane.
Plant cells have a nucleus, cytoplasm and a cell membrane, and
vacuole, chloroplasts and a cell wall.
Cell division is a means of increasing the number of cells in an
organism.
Cell division is essential to allow organisms to grow and repair
damaged parts, for example cuts and broken bones.
The nucleus of the cell controls cell activities including division.
During cell division, the parent cell divides to produce two identical
cells.
Each of the two cells produced by cell division contains the same
number of chromosomes in their nuclei as the parent cell.
It is important that the chromosome complement of daughter cells
in multi-cellular organisms is maintained so no important
information is lost.
State that cancer occurs as a result of uncontrolled cell division.
Skills that I should be able to carry out by the end of this unit are: Make a slide and view it under a microscope. Calculate the magnification used to view a specimen. Describe the main stages of mitosis. Identify the correct sequence of the stages of mitosis. Select information from different sources. Work as part of a group and take responsibility to support the work
of the group.
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Investigating Living Cells Copy this note
All living things are made of one or more cells.
Cells are the basic units of living things.
Living things made of more than one cell are called multicellular.
Living things, which have only one cell, are called unicellular.
Cells are too small to be seen with the naked eye. If we want to see
cells clearly we have to use a microscope.
The Microscope
The microscope is an instrument which magnifies things.
The diagram below shows a simple light microscope.
Eyepiece Lens
Objective Lenses
Stage
Focussing Wheels
Mirror
Activity 1
Collect and label the
microscope diagram.
Glue it into your jotter
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Copy and complete the table below
Part of Microscope
Function
Eyepiece Lens
Objective Lens
Stage
Clips
Mirror
Focussing Wheels
How to use the microscope
1. Switch on the light or adjust the mirror so that it is bright when you look through the eyepiece
2. Set the lowest power objective lens immediate over the stage.
3. Place your slide on the stage, with the specimen under the objective lens.
4. Lower the low power lens as close to the stage as possible.
5. Look through the eyepiece, and using the coarse focus wheel, move the stage and the objective lens slightly apart, until the specimen comes into focus.
6. If you require further magnification, turn onto the medium power lens, and refocus using the fine focus wheel. This can be repeated using the high power lens.
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Copy and complete the note below
Magnification
The magnification of the microscope describes how many times bigger the image appears.
Total Magnification = Eyepiece Magnification X Objective Lens Magnification
Lens
Eye piece
magnification
Objective lens
magnification
Total magnification
Low Power
Medium Power
High Power
Activity 2
View a selection of prepared slides through the microscope. Draw what
you see in your jotter and under each drawing write the title of the
slide and the magnification used to view it.
Answer the following questions in sentences
1. Why do we put the slide under the spring clips on the stage of the microscope?
2. Using high power, would you see more or less detail than when
you use low power?
3. When you are focusing on an object in which order should the three objective lenses be used?
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Cells Cells are the basic units of life. Although cells vary in shape and size they do have some structures in common.
Comparing plant and animal cells
Activity 3
Collect the diagrams of animal and plant cells shown below
Watch the video ‘Bill Nye-Cells’ and the Power Point about cells
Use the video and the PowerPoint to label the diagrams and stick
them into your jotter
An Animal Cell
A Plant Cell
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Copy and complete the table below by placing a tick() or a
cross() in each box.
Complete the following task in your jotter
Describe the similarities and differences between an animal cell and a
plant cell.
Name of
cell structure
Is it present in plant
cells?
Is it present in animal
cells?
Nucleus
Cytoplasm
Cell membrane
Cell wall
Chloroplast
Vacuole
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Activity 4
Use a microscope to view the cell slides provided. Identify which are
slides of plant cells and which are slides of animal cells. Ask you teacher
to check your answers.
Each part of the cell has a special job to do.
Copy and complete the table below
Name of cell
structure Function
Nucleus
Cytoplasm
Cell membrane
Cell wall
Chloroplast
Vacuole
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Activity 5
Watch PowerPoint ‘making slides’
Your teacher will show you how to collect onion epidermis tissue
and make a slide to examine under the microscope.
Make a slide of your specimen and view under:
Low power
High power
Draw clear labelled diagrams of the cells.
Repeat for Cheek epithelium tissue.
Repeat the activity using Iodine Solution to stain the onion cells and
Methyl Blue to stain the human cheek cells. Stains are used to show
up the parts of the cell more clearly.
Answer the following questions in your jotter
1. Why do we use stains when making slides to view through a microscope?
2. What stain would we use when viewing onion cells?
3. What stain would we use when viewing cheek epithelial cells?
4. What part of the cell was made most visible by using the stains?
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Cell division and its role in growth and repair
Cell division is essential to all living organisms. Cell division is called
mitosis.
Cell division is a process which can increase the number of cells in an organism.
Unicellular and Multicellular Organisms
Some living things consist of only one living cell, e.g. bacteria. We
call them single-celled or unicellular. However, most living things
have bodies which are made up of many cells and they are said to be
multicellular.
Single Celled Organisms
In a unicellular organism, cell division is a form of reproduction that
produces two new individual organisms.
Multi-Cellular Organisms
animal cell nucleus dividing cytoplasm two daughter (eg. Amoeba) into two dividing cells formed about to divide
In a multi-cellular organism, for
example humans, cell division
is essential to allow growth and
repair of damaged parts, for
example cuts and broken
bones.
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Activity 6
In your notebook copy the headings below.
Leave a space under each heading.
Look at the power point on cell division.
Record the information in your own words to show how cell
division (mitosis) is involved in each process.
1. Reproduction in unicellular organisms
2. Growth in animals
3. Growth in plants
4. Repair of tissue
5. Regeneration in starfish
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Mitosis Copy this note Animal and plant cells contain a nucleus.
The nucleus controls all the cell’s activities, including cell division.
The nucleus of the cell contains thread-like structures called
chromosomes. Chromosomes carry genetic information which
determines the correct structure and function of every cell in the
organism.
The diagram below shows the structure of a chromosome.
Humans have 46 chromosomes in the nucleus of body cells (non-sex
cells).
Chromosomes in
a normal body
cell of a human
female.
Collect this
diagram and
stick it in
your notes
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These chromosomes can be arranged in 23 pairs. (Two sets of 23)
When a cell divides each new cell has 46 (23 pairs) chromosomes in
the nucleus.
Parent cell
Daughter cells 46 46
46
Collect this diagram and stick it in your notes
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The stages of mitosis copy this heading
Activity 7
Collect the stages of mitosis handout.
Watch the power point on mitosis and use the information to complete
the handout.
Glue the completed sheet into your jotter.
Copy and complete this note
The process of cell division (or MITOSIS) produces 2 i____ __ cells
each with the same number of c________ as the parent cell from which
they were formed. This is important because it ensures that no
i i is lost, and therefore each of the two
new daughter cells has the same genetic information as the
cell so that they will grow and develop properly.
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Activity 8
Now, using a microscope and the bioviewers, look at the slides of cells dividing by mitosis.
Answer the following questions in your jotter
1. How many chromosomes can you see in the cell on slide 4?
2. What has happened to the chromosomes on slide 5?
3. What is pulling the chromosomes apart on slide 7?
4. Look at slide 8. How many cells have been made?
Activity 9
Complete the Mitosis Card Sort. Ask your teacher to check your answers.
Activity 10
Collect a mitosis model kit. Using the contents model the stages of
mitosis.
Your teacher may allow you to make a poster showing the stages of
mitosis.
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Growing cells copy this heading
Scientists take advantage of cell division by growing cells in the lab. The process of growing cells in the lab in either solid or liquid media is called cell culture.
Cells are grown in culture to make food and drink such as mycoprotein (Quorn), beer and wine, to test antibiotics, vaccine and medicines and to learn about cell division.
It is possible to grow a layer of cells in dishes/bottles which can then be used for a variety of purposes. Current research is being done to use cells grown in the lab as skin grafts for burn victims and even to grown whole entire organs – this is very much still experimental!
Answer the following questions in your jotter
1. What do we call the process of growing cells in a laboratory?
2. Name a food produced by cell culture?
3. Give a use for skin cells grown in the laboratory?
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Cancer copy this heading
Cancer occurs as a result of uncontrolled cell division.
The body is made up of many types of cells. These cells grow and divide
in a controlled way to produce more cells as they are needed to keep
the body healthy. When cells become old or damaged, they die and are
replaced with new cells.
However, sometimes this orderly process goes wrong. The genetic
material (DNA) of a cell can become damaged or altered, producing
changes (mutations) that affect normal cell growth and division. When
this happens, cells do not die when they should and new cells form
when the body does not need them. The extra cells may form a mass of
tissue called a tumour
Activity 11
Watch the film clip ‘What is Cancer?’
Using the information in the video and any other sources
available write short notes on
The causes of cancer
What cancer is
Ways to reduce the risk of cancer
