THE CELL THEORY
MICROBIOLOGY
 The
study of microscopic organisms
that are too small to be seen by the
naked eye.
WHAT IS A CELL?
A Cell is the basic structure which makes up all
living organisms.
 A cell can exist by itself (unicellular) or with
many other cells (multicellular)

THE CELL THEORY
1. All Living Things are Made up of Cells
 2. Cells are the Basic Unit of Life
 3. All Cells Come From Pre-Existing Cells

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ROBERT HOOKE

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Robert Hooke was the first person to view and
describe cells under a microscope.
EXPERIMENT: PLANT AND ANIMAL CELLS

Aim: To view and compare the differences of plant
and animal cells.
Method:
1. Set up the microscope and turn on.
2. Collect a pre-prepared slide and place under the
microscope using the stage clips.
3. Ensure the objective lens is on low, and using the
adjustment knob, bring into focus.
4. Draw a cell.
5. Remove the slide, and repeat with the other preprepared slide.

EXPERIMENT: PLANT AND ANIMAL CELLS
Results:
Plant cell:

Animal Cell:
EXPERIMENT: ONION SLIDES

Aim: To make an onion slide and investigate the
cells in the onion.
Method:
1. Cut a small piece of onion and carefully remove
the skin on the onion
2. Place the skin on the slide
3. Add 1-2 drops of iodine solution
4. Lower the coverslip over the onion skin
5. Remove excess stain
6. View under microscope on low power
7. Draw a labelled cell

EXPERIMENT: ONION SLIDES

Results:
EXPERIMENT: ONION SLIDES

Conclusion: An onion cell is a plant cell because
it has a cell wall.
3 DIFFERENT TYPES OF CELLS

Animal Cell

Plant Cell

Bacteria Cell
ANIMAL CELL
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PLANT CELL
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DIFFERENCES OF PLANT AND ANIMAL CELL
Animal Cell
Plant Cell
Small Vacuole (some)
Large Vacuole
No Chloroplasts
Chloroplasts
No Cell Wall
Cell Wall
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FUNCTION OF ORGANELLES
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Cell Organelle
Function
Nucleus
Controls the activities of a living cell
Cytoplasm
Jelly-like substance which fills most of the
cell
Mitochondria
The site of cellular respiration. Where
energy is made in the cell
Vacuole
Water storage
Cell Membrane
Thin layer surrounding the cell which
controls the movement of substances into
and out of the cell
Cell Wall*
Tough outer layer of a plant cell that helps
keeps its shape
Chloroplasts*
Found only in plant cells which contain
chlorophyll and are the site of
photosynthesis
BACTERIA CELL

The Simplest type of cell
CELLULAR RESPIRATION
Mitochondria
CELLULAR RESPIRATION
Cellular respiration occurs inside mitochondria.
This process involves glucose (from the food we
eat) and oxygen to react together to form water,
carbon dioxide and energy.
 This energy is used by our bodies to help us
function.

(Sugar)
IMPORTANCE OF RESPIRATION

Cellular respiration is important because it
provides energy for the living organism to
perform all other necessary functions to maintain
life.
RESPIRATION AND BREATHING
It is important not to confuse respiration with
breathing. Respiration is a chemical reaction that
occurs in the mitochondria inside cells.
 Breathing is a process performed by multicellular
organisms that have lungs or gills to exchange
gases with the environment.
 Breathing usually involves taking oxygen into
the body and expelling carbon dioxide back into
the environment.

EXPERIMENT: EXTRACTING CHLOROPHYLL
Aim:
 To extract chlorophyll from leaves and
investigate the colour of leaves without
chlorophyll.
Method:
1. Pick a leaf from a tree
2. Boil the leaf in a beaker of water for 2 minutes.
3. Pour 20mL of ethanol into a small beaker and
place leaf inside
4. Place beaker in hot water bath
5. Record Results
EXPERIMENT: EXTRACTING CHLOROPHYLL
Results:
Colour Before
Colour After
Ethanol
Leaf
Clear
Green
EXPERIMENT: EXTRACTING CHLOROPHYLL
Conclusion:
We found that chlorophyll is green and gives leaves
the appearance of the colour green. This is because
the leaf turned clear and the ethanol turned green.
UNICELLULAR AND
MULTICELLULAR ORGANISMS
UNICELLULAR ORGANISMS
Unicellular organisms are organisms which are
made up of only one cell.
 An example of a unicellular organism is bacteria.

MULTICELLULAR ORGANISMS
Multicellular organisms are organisms which are
made up of more than one cell. There are
different types of cells in multicellular organisms
because they carry out different functions. These
are called specialised cells.
 Examples of multicellular organisms are plants
and animals.

CELLS, TISSUE, ORGANS, SYSTEMS, ORGANISM

All living organisms are made up of cells. A bunch of
cells together are called tissue. Organs such as the
heart, lungs, liver are made up of tissue. And it is
these organs that then make up different systems in
the body such as the circulatory, respiratory and
digestive system. There are various systems in the
body which make up an entire organism, which is
you and me!
SPECIALISED CELLS

Different types of cells have different cell
components to enable them to carry out their
specific roles. These differences in the structure
and function of cells can be used to classify them