Cells and Cell
Parts
Grade 8 Science
Parkland Junior High
2012-2013
The game of life so far…
 Cell
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Theory:
Formulated by Schleiden, Schwan, and
Virchow in the 19th century
States that:
all living things are composed of one or more
cells
 The cell is the basic unit of life
 All cells come from already existing cells

The Cell as a City
 http://www.youtube.com/watch?v=o1G
QyciJaTA&feature=related
A cell is
 The
smallest unit that
can perform the
functions of life
 A cell is like a small city
where every structure
has a purpose to keep
the city running
smoothly.
 Every cell must carry
out certain activities
that keep it alive.
Cell Structure

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All cells have similar basic
structures in common even
though the shape, size,
colour may vary.
These basic structures carry
out the functions of the cell.
These structures are known
as organelles.
Organelle means “little
organ”
Each organelle has a role to
play in the activities
necessary for life.
Organelles found
in Plant and Animal Cells
 Plant
and animal cells share similar structures and
have organelles that perform the same functions.
Cell Membrane
 The
cell membrane is like
the skin covering your body
or the shell surrounding an
egg.
 This membrane is not only
for protection but also
allows and controls the
movement of substances in
and out of the cell.
 In our “city cell”, the cell
membrane would be like
the city boundaries.
Cytoplasm

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Much of the inside of the
cell is made up of
cytoplasm.
Cytoplasm is constantly
moving inside your cell and
it distributes materials such
as oxygen and food to
different parts of the cell.
In our “city cell”, the
cytoplasm would be similar
to all the parks and
greenspace in town
because it fills all the space
where other organelles are
not found.
Golgi Apparatus
The Organelle
of
Many Names
Many Names…
 This
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organelle has many different names:
The Golgi Apparatus
The Golgi Body
The Golgi Complex
Nice ‘stache,
dude!
It was identified in 1897 by the Italian
physician Camillo Golgi and named
after him.
What does it do?
 The
organelle’s main
job is to package
big molecules (like
protein and fat)
after they are made
(or used up) by
other parts of the
cell. These packages
are called vesicles.
What does it look like?
A
series of stacked
membranes. Unlike
the twisty
Endoplasmic
Reticulum, the Golgi
Body is stacked –
kind of like a stack of
pancakes.
 Small vesicles that
look like bubbles are
found inside the
Golgi Body, as well
as around it.
Role in the “Cell City”
 The
golgi works like a post office. The post office
sorts packages by destination (domestic and
international). It boxes and labels the packages
and then distributes them to their final
destination
Miss Golgi?
Endoplasmic Reticulum
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Here are our highway and
road system in our city.
Goods are manufactured
and shipped to needed
areas via this road system.
The ER is a folded
membrane that forms a
system of canals within the
cytoplasm.
Materials are transported
through these canals to
different parts of the cell or
to the outside of the cell.
Rough Endoplasmic Reticulum

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The rough endoplasmic
reticulum is studded with
ribosomes giving it a rough
appearance. It is
continuous with the nuclear
membrane. This means it
extends out directly from
the nuclear membrane into
the cytoplasm.
The ribosomes on the rough
endoplasmic reticulum
make proteins that are
exported from the cell.
Smooth Endoplasmic
Reticulum
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The smooth endoplasmic
reticulum (SER) is not
studded with ribosomes
giving it a smooth
appearance. The
membranes of the SER
extend from the RER in the
cytoplasm.
The SER has two functions;
it synthesizes lipids and
detoxifies harmful
substances. It also helps in
the packaging of materials
inside the cell.
Ribosomes
 Ribosomes
assemble
protein according to
the cells specific
genetic instructions
and are found on the
RER and “free” within
the cytoplasm.
 Ribosomes help in
protein synthesis. The
RER “pinches” off the
ribosomes so they can
move throughout the
cell.
Nucleus
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The nucleus is the most easily seen organelle in the cell.
It would be the mayor of our city cell.
The nucleus controls the cells functions and activities.
The nucleus houses the majority of genetic material of a
cell. The nucleus is the brain of the cell and controls all
activity within the cell, using DNA as a blueprint (like the
blueprints of a city)
Nucleus continued…
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Inside the nucleus you will
find chromosomes.
These structures are made
of genetic material that
direct a cell’s growth and
reproduction.
The nucleus is also
surrounded by a nuclear
membrane which controls
what enters and leaves the
nucleus. Think of this as
security surrounding the
mayor of our city and city
hall.
Chromosomes
A
chromosome is a
threadlike structure in
the nucleus of a cell.
The chromosomes
carry the genetic
material (DNA) for the
cell. There are 46
chromosomes in every
human.
Cell Wall
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So if our city cell was a plant
cell, we wouldn’t have just a
boundary or a border, we
would have a fortified wall
surrounding our city.
Cell walls are much more
rigid and thicker than the cell
membranes found in animal
cells.
The cell wall provides support
for the cell. Cell walls are
much thicker and more rigid
than cell membranes and are
made mostly of a tough
material called cellulose.
Cell Wall
 The
cell wall occurs
only in plants, fungi,
and some unicellular
organisms.
Chloroplasts

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Chloroplasts are the solar
energy plants in the city cell.
Like a solar energy plant they
use sunlight to create energy
for the city.
Chloroplasts are the site of
photosynthesis a process in
which the plant uses carbon
dioxide, water and sunlight to
create energy in the form of
glucose for the plant cell as
well as the organisms that
consume the plant.
Folded membranes inside
each chloroplast contain the
green pigment chlorophyll
which absorbs sunlight.
Chloroplasts

Chloroplasts are found only
inside cells in green plants
and in some unicellular
organisms. They are not
found in animal cells.
Energy for Cells
Cells
need energy for
all life processes.
Energy is stored in
food called glucose (a
type of sugar)
To
release energy cells
must carry out cellular
respiration. Here the
energy is converted to
another form of energy.
Takes place in the
mitochondrion.
Mitochondria
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Welcome to our energy
plant!!
Because cells do work, they
need energy. Their energy is
produced by oval-shaped
organelles called
mitochondria.
Inside the mitochondria, tiny
food particles are broken
down to release their
chemical energy for the
cell’s activities.
Some cell’s such as muscle
cells have more
mitochondria than others
because they need more
energy to function.
• Most
energy is released as
heat.
• Oxygen is necessary for
cellular respiration.
• Carbon dioxide and water
vapour are waste gases
produced. These are
removed from the cell.
Dividing Cells
Necessary
for growth
and reproduction
Will replace cells that
are dead or in need of
repair
How does this happen?
Mitosis
Occurs
in body cells
(somatic cells) not in
gamete cells.
Cell Parts and
Cell Size Part 2
Plant vs. Animal
Parkland Junior High
Mrs. Friesen
PLANT
ANIMAL
Cell membrane
Cytoplasm
Cell wall
Brick shape
Round shape
Nucleus
Vacuole
Mitochondrion
Chloroplast
Large & few
Small & many
Plant Vs. Animal Cells
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Now that you know some important cell
organelles, we need to identify those that
distinguish plant cells from animal cells.
There are three organelles that are found only
in plants and not in animals.
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1) cell wall (versus a cell membrane in animal
cells)
2) central vacuole (regular vacuoles are found in
animal cells)
3) chloroplasts (animals do not perform
photosynthesis and therefore do not have
chloroplasts).
Comparing Plants and Animal
Cells
 Plant
and animal cells are very similar but there
are some important differences that we need to
remember:
 Plant cells have chloroplasts because they
make their own food. As well, plant cells have
a cell wall. Animal cells do not either.
 Plant cells have a single large vacuole. Animal
cells have many small vacuoles.
 Plants use photosynthesis. Animal cells do not.
 Plant cells have a regular shape (usually
rectangular). Animal cells are circular or
irregular in shape.
Plant vs. Animal Cells
Vacuole
Here are some
pictures of real
cells.
Can you pick out
some of the
major organelles?