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Life Science
Grade 6, Unit 6L1. Cells
Unit 6L.1: Cells
• Living things are made
of Cells
• Specialized cells
• Tissues and Organs
• Cell Division
By the end of this unit you will know:
• All living organisms are made of cells.
• A collection of specialized cells makes tissues.
• Organs are made up of tissues of different types.
• Living organisms are made of many organs that have
different functions.
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Life Science
Grade 6, Unit 6L1. Cells
Living things are made of cells
All living things are made up of small parts called Organs.
These organs are made up of lots of even smaller bits called
cells.
Some organisms such as BACTERIA are made up of only one
cell. Large organisms like mice and insects are made up of many
cells.
A human for example is made up of trillions of cells – Do you
know how man zeros in a trillion.
Can you imagine how many cells a whale must have?!!!!!
The cells are the building blocks of all living things
6.5.1, 6.5.2
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Life Science
Grade 6, Unit 6L1. Cells
Cells are very small. You need a microscope to see them.
Microscopes make things look a lot bigger. We say that they
magnify them. (Look at box 1 on Page 4).
If you magnify cells a hundred times or more, you can even see
the smaller parts inside them.
The Cell Theory: Matthias Schleiden in 1838 and Theodor Schwann in 1839 realized that all plants and animals were made up of cells. The Cell theory changed the way that Scientists thought about living things for ever.
The Microscope was invented in the 16th century, but it was not until 1665 that a Scientist called Robert Hook published a book that showed drawings of a part of plant he had seen under the microscope. He called the tiny boxes he had seen Cells because they reminded him of the small rooms (cell means little room in Latin).
Hook microscope
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Life Science
Grade 6, Unit 6L1. Cells
Optic tube
Arm
Coarse Focus
Fine Focus
Base
Eye Lens
Objective Lens
Stage
Light
You must handle the microscope with care. It is delicate and very expensive! Follow you teacher’s instructions before using it!
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Life Science
Grade 6, Unit 6L1. Cells
UThe light microscope The Microscope is an instrument used to magnify the tiny things. Look at the picture (on page 4) and identify the main parts of the microscope. Read them out to yourself. Notice that it is made of 2 lenses:
• The eye piece lens and the objective lens. The total magnification=
Magnification of the eye lens x Magnification of the objective lens
The eye piece lens is usually (*10) There are three Uobjective lenses (that rotates round) U:
- (x4),(x10), (x40) The highest magnification in this microscope is (10x40) = 400 times the size! Do you know what this is? It has been magnified 400x!
Rewrite the words below in reverse and find out: The first word has been done for you in red... GEL FO A OTIUQSOM LEG
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Life Science
Grade 6, Unit 6L1. Cells
ULet’s see what a cell from your body looks like. Activity: You will need the following:
• A microscope. • A cotton bud. • A dropper with water. • A glass slide and a cover slip. • A Methylene Blue stain.
What you should do: 1. Put a drop of water on the centre of a glass slide.
2. Gently wipe the inside of your cheek with the cotton bud. 3. Put the end of the cotton bud on the drop of water. Stir a few times. 4. Add a drop of stain.
5. Hold the cover slip by its edges. Hold it at one end of the slide (look at the picture below).
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Life Science
Grade 6, Unit 6L1. Cells
6. Slowly move the cover slip until it is over the water. 7. Carefully drop the cover slip.
8. Put the slide on the microscope. Turn to a low magnification. Look into the lens. Focus it. What do you observe? ------------------------------------------------ (You should see many purple dots. They are cheek cells!)
9. Draw what you see in your notebook.
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Life Science
Grade 6, Unit 6L1. Cells
You should see something like the following under a low magnification (Fig.1). If you can put it on high magnification you should see something like (Fig.2).
UWhat do cells look like?
UPlant cellU UAnimal cell
Cells are made of lots of different parts. Each part has a different job to do, to keep the cells alive and working.
1. UAnimal cellU:
Most cells have the same basic structure. The cell itself is
made of smaller parts. Most cells have three main parts:
Fig.1
Fig.2
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Life Science
Grade 6, Unit 6L1. Cells
Cell part Function Cell Membrane controls what passes in and
out of the cell Nucleus controls what happens in the
cell.
Cytoplasm which is a jellylike material made mostly of water that fills the space in the cell.
Animal cell
Cell membrane
Cytoplasm Nucleus
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Life Science
Grade 6, Unit 6L1. Cells
2. UPlant cellU: Plant cells have the same parts as animal cells. They also have certain parts that animal cells do not have. These extra parts are:
Cell part Function
Cell wall outer skeleton of the plant Chloroplasts contains the chlorophyll.
A large Vacuole a store of water in the plant cell.
Plant cell
Large Vacuole
Cytoplasm Cell Wall
Nucleus
Cell membrane Chloroplast
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Life Science
Grade 6, Unit 6L1. Cells
Activity: Preparing to look at onion cells under a microscope. Follow the directions: (Note: Onion cells do not have chloroplasts. If you want to look at them, find a moss plant.)
1. Cut out a small piece of onion. 2. Use forceps or your finger nails to
peel off the inner surface (this looks like tissue paper).
3. Put the piece of onion “skin” flat on a slide and add 2 drops of iodine solution.
4. Gently lower the cover-slip onto the slide using a mounted needle.
5. Place the slide onto the stage of the microscope.
6. Focus carefully onto the onion skin using the lowest power objective lens in your microscope.
7. Turn on the high power objective lens to see details of the onion cells.
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Life Science
Grade 6, Unit 6L1. Cells
S
Key ideas: • All living things are
made of tiny bits called Cells
• All cells have: o Nucleus o Cell membrane o Cytoplasm
• Plant cells also have: o Cell wall o Chloroplasts o A large vacuole.
• Cells are too small to be seen by naked eye. So we need a microscope that magnifies them.
Project: Use the following materials to make a model of a plant cell:
Material Cell part A plastic jar A small plastic bag A large plastic bag A balloon modelling clay Sand + water
1. Plan your project – by
deciding on what will represent the cell parts
2. Make the model - label each part so it is clear, don’t forget to write your name!
Key words: • Nucleus • Cell membrane • Cytoplasm • Cell • Cell wall • Chloroplasts • A large vacuole.
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Life Science
Grade 6, Unit 6L1. Cells
Key Questions: Q(1) Complete the following gaps : 1-All plants and animals are made up of tiny units called _______. 2- A ___________which controls what happens in the cell. 3- ________ is made mostly of water that fills the spaces in the cell. 4- A ________ that covers the cell and controls what goes in and out of the cell. Q(2) Can we use a magnifying lens to see the cells? Explain your answer. -------------------------------------------------------
-----------------------------------------------------
Q(3)Using Venn diagram compare between the parts of Animal and
plant cell ?
Q(4) Draw Animal cell and label all parts ?
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Life Science
Grade 6, Unit 6L1. Cells
Specialized cells
Large organisms have millions of cells of different types (multicellular organisms). These cells are different from each other because they have their own jobs to do.
Animals and plants are large living organisms. They need food, they need to breathe and move. To do all these jobs they need millions of specialized cells.
Specialized cells: Cells that have different shapes and do different jobs
6.5.3
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Life Science
Grade 6, Unit 6L1. Cells
Activity: Looking at pre-prepared slides
1. Use the microscope to look at two different
animal cells, and two different plant cells.
2. Make sure to look for the main parts of the cells.
(Nucleus, Cell Wall, Shape, Cytoplasm, Vacuole)
3. Make a table, draw what you see for each slide and tick
off the parts you can see, so that you can compare.
Animal Cell Plant Cell
Slide 1 Slide 2 Slide 1 Slide 2
What did you
see?
Draw a sketch
here
Nucleus Yes / No Yes / No Yes / No Yes / No
Cell Wall Yes / No Yes / No Yes / No Yes / No
Cytoplasm Yes / No Yes / No Yes / No Yes / No
Vacuole Yes / No Yes / No Yes / No Yes / No
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Life Science
Grade 6, Unit 6L1. Cells
Some examples of specialized cells and their functions are shown in the following table:
Cell Function Special characteristics Animal Cells
Muscle cells
Contracts so that we can move
Has fibres that can become short or long to help in
movement.
Sperm cells
Fertilization (from male)
Has a tail to swim
Nerve cells
Conducts nerve impulses
(messages from and to the brain)
Has a long fibre that can
reach 2 meters
Plant cells
Palisade
Catch the light
Has a large number of Chloroplasts.
Xylem and phloem
Transports water and nutrients
- Tube like cells to carry water and nutrients. - Xylem cells have no
cytoplasm
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Life Science
Grade 6, Unit 6L1. Cells
Key ideas: • Large living organisms have millions of cells that have
different functions and different shapes. These cells are called Specialized Cells.
• Muscle , nerve and sperm cells are examples of Specialized animal cells.
• Xylem, Phloem and Palisade cells are examples on specialized plant cells.
Key Words: Specialized Cells , Palisade cells, Xylem and Phloem.
Sperm, muscle, nerve cells.
Project: Find the function of the following specialized cells: Make a poster and comment on the: shape, what it does, where you find it. Egg cell Root hair cell Red blood cell
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Life Science
Grade 6, Unit 6L1. Cells
Key Questions: Q (1): Put (T) if the statement is true or (F) if the statement is false:
1- Sperm cells have fibres that can become short or long to help in movement ( ).
2- Xylem cells have no cytoplasm ( ). Q (2): Look at the pictures and answer the following questions:
A B 1- Write the name of cell
(A)?
--------------- 2- Write the function of cell
(B)?
---------------- 3- What characteristic does
picture (A) help to movement ?
--------------------
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Life Science
Grade 6, Unit 6L1. Cells
Tissues and Organs
One Xylem cell will not be able to carry water and nutrients to the whole plant. One muscle cell will not be responsible for the movement of your whole body. Specialized cells have to work together to do the job.
All the cells in a UtissueU look the same and do the same job. For example: Your Umuscle tissueU is made of identical muscle cells.
A collection of cells with the same shape and function is called a Tissue.
6.5.4
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Life Science
Grade 6, Unit 6L1. Cells
Activity: You can see what a tissue looks like: Get some raw hamburger meat (it is muscle tissue that looks a lot like muscle tissue that is in the human body). Materials: Microscope, a dropper with water, a glass slide and a cover slip. What you should do:
1. Put three drops of water on the slide.
2. Put a cover slip over the hamburger.
3. Put the slide under the microscope. You should see tissue (Cells that look alike). Draw what you see.
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Life Science
Grade 6, Unit 6L1. Cells
Examples of Animal tissues:
Example picture
Muscle tissue
Epithelial tissue (on the skin)
Brain tissue
Blood tissue
Nerve tissue
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Life Science
Grade 6, Unit 6L1. Cells
Examples of plant tissue: U1.Stem tissue
This is how a part of the stem looks like under the microscope. Notice the Xylem and Phloem cells that have the same shape and same function.
U2.Leaf tissue: Palisade cell
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Life Science
Grade 6, Unit 6L1. Cells
Organs:
Like plants, our body has many different parts called Organs.
Different organs in our body do different jobs. An organ is
made up of different tissues that work together to do a
particular job.
Examples of organs:
Your heart is an organ. It is made of different tissues that
work together to pump blood around your body.
Your stomach is an organ; it helps your body
break down your food.
An organ is a body part made of different tissues that work together to do a particular job.
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Life Science
Grade 6, Unit 6L1. Cells
The stomach is made of many tissues shown in the following
picture. It is made of layers of different tissues – like a hard
boiled egg– you can peel the layers off and see them!
Other examples of organs are lungs, livers, leaves and
stems.
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Life Science
Grade 6, Unit 6L1. Cells
This picture shows how organisms are made, you can see that the cells, are the building block for the living organisms, then groups of cells together form a tissue . A tissue is a group of similar cells that work together to do one job. Each cell in a tissue does its part to keep a tissue alive . Tissue organized into organ , different organs make organ system .
Cell Tissue Organ Organ system Organism.
Project: 5 tissue types in your body are: connective, muscle, nervous, and epithelial. Make a poster, explaining what jobs they do and why they are so important.
Here is an example.
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Life Science
Grade 6, Unit 6L1. Cells
Key Questions: Q(1) : complete the following gabs :
• The different parts of your body are called_________
• A group of specialized cells that work together are
called ________________
Q(2): Sort these lists into the correct sequence of cells, tissue, organ, organism:
a. Heart, muscle, human, muscle
b. Shark, nerve, eye, retina
Q(3) : List three organs in plants.
1- _________________________
2- _________________________
3- _________________________
Key words: • Specialized cells • Collection • Tissue • Organ
Key Ideas: - A tissue is a group of cells
that look alike and work together to do a specific function.
- An organ is made of many layers of different tissues.
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Life Science
Grade 6, Unit 6L1. Cells
Cell Division
How do living things change so much as they grow ? A bird
starts out in a hard shelled egg you can hold in your hand. How
does it end up as an eggle made of billons and billons of cells
and covered with feathers ?
What happens when you grow? Do cells get bigger or do they
increase? where do new cells come from?
Cell Division
Cells are basic units of living things. Most of the organisms
such as dogs, cats , birds and trees made of many cells .
When the cells of these organisms divide, they do not
separate.
The cells stay together and keep on dividing. As the cells
divide, the organisms grow and changes.
6.5.5
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Life Science
Grade 6, Unit 6L1. Cells
A single bird or tree is made up of billions of cells. Your body
has billion of cells too. All the time you are growing, your
body's cells are dividing. Notice how much the child in the
picture has grown.
Your cells will keep on dividing, even when you stop getting
bigger and taller. Your body need to make new cells because
the new cells replace old cells that wear out or die.
How cell division happened?
When a cell starts to divide ,it make a copy of all its part
After the cell divides ,the new cells will have parts that are
identical to the ones the original cell had. The information that
a cell needs in order to control all its acivites is stored inside
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Life Science
Grade 6, Unit 6L1. Cells
the Ucells nuclues U . This information is located in a set called
chromosomes.
Look at the picture of the dividing cell.
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Life Science
Grade 6, Unit 6L1. Cells
Sequence of cell division:
1-Chromosomes are copied First, the cell copies its chromosomes. It makes two complete sets .
2- Chromosomes line up The two set of chromosomes line up in the canter of the cells.
3-Chromosomes separate
Then the two sets of chromosomes separate each set moves toward on opposite side of the cell
4-Chromosomes Divide
Finally , the cytoplasm divides, formatting two new cells.
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Life Science
Grade 6, Unit 6L1. Cells
Key words: • Cell division • Chromosomes
Key Ideas: - As the cells divide, the
organisms grows and changes. - Even when you stop getting
bigger and taller. Your body need to make new cells because the new cells replace old cells that wear out or die.
Key question 1- Why is cell division important?
____________________________________________________________________________
2- Draw and describe how cell divide in the space below?
