Cell Structure
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Students know and understand the
characteristics and structure of living things,
the processes of life, and how living things
interact with each other and their environment.
Benchmark 3.9: Cellular organelles have
specific functions.
Assessment Objective 3.9a: Describe the
function of cellular organelles.
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Centriole
Chloroplast
Chromatin
Chromosome
Cilia
Cytoplasm
Endoplasmic reticulum
Eukaryote
Flagella
Golgi body
Lysosome
Metabolism
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Videos approximately 35:00
minutes
Microfilament
Microtubule
Mitochondria
Nucleoli
Nucleus
Organ
Prokaryote
Ribosome
Symbiosis
Organ System
Tissue
Vacuole
Colonial organism
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All living things are
made up of one or
more cells.
Cells are the basic
units of structure and
function in organisms.
All cells arise from
existing cells.
Eukaryote/Prokaryote
What am I?
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Cells are:
Three-dimensional
Shaped like spheres,
cubes, or bricks.
One-celled
(unicellular)
organisms may be
either prokaryotes or
eukaryotes.
Bacteria are
prokaryotes.
Primitive cells (0:46)
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Other unicellular and
multicellular but
lacking specialized cells
are members of the
Family Protista.
An example is euglena
of the Phylum
Euglenophyta. They
can make their own
food by photosynthesis
and also ingest food
from their
surroundings.
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Parts of an animal cell (4:55)
Many-celled organisms
that evolved from
unicellular organisms.
Almost all carry out
basic functions.
Ex: Not all tree cells
perform photosynthesis,
only those with
chlorophyll.
Specialized cells like
blood cells are
dependent upon one
another.
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A group of cells that
have the same structure
and function is called a
tissue.
Examples of cells that
make up tissues
include:
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Skin cells (0:37)
Muscle cells (0:49)
Bone cells (0:13)
Nerve cells (1:12)
Blood cells (1:16)
Cell Review (1:57)
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Cells work together to
form tissues.
Tissues work together to
form organs.
An organ is a structure
composed of many
different tissues that work
together to perform a
particular function.
Your heart is an example
of an organ.
A group of organs
working together form a
system.
Systems working together
form an organism
Organs
(1:01)
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Cytoplasm (1:30)
Cytoplasm, found in the
cell, is composed of 70%
water, 30% proteins, fats ,
carbohydrates, nucleic
acids, and ions.
The exact composition
varies from cell to cell
because of chemical
changes.
The sum of all the
chemical changes is called
metabolism.
Cytoplasm has three main
functions: energy, storage,
and manufacturing.
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Almost all living cells
contain organelles that
are surrounded by a
membrane.
There are two types of
cells:
Eukaryote: Cells that
contain a nucleus.
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Example: Almost all
cells in the living world.
Prokaryote: Cells
without a membrane or
nucleus.
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Example: bacteria
Comparing prokarytoic
and eukaryotic cells (0:30)
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Nucleus
Nucleolus
Endoplasmic Reticulum (ER)
Centriole
Centrosome
Golgi Apparatus
Cytoskeleton
Cytosol
Mitochondrion
Secretory Vesicle
Lysosome
Peroxisome
Vacuole
Click on picture for interactive cell models
Ribosome
Includes animal, plant, bacteria and
prokaryote cells
courtesy: cellsalive.com
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The cell membrane is
a semi-permeable
membrane that
regulates what goes in
and out of the cell.
They also define the
different
compartments of the
cell like the nuclear
membrane.
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The nucleus is the control center of
the cell.
It has a double membrane with a
dense mass of material called
chromatin.
The chromatin is made up of
individual chromosomes.
The nucleus has nuclear pores that
allow it to communicate with the
surrounding cytosol.
Chromosomes are made of
proteins and DNA that determines
both inherited traits and
instructions that are copied into
the RNA for the production of
proteins.
By coding for RNA, DNA controls
the activities within the cell.
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The nucleolus is
found in the nucleus.
It produces ribosome
parts which travel
outside of the nucleus
to form ribosomes.
Ribosomes then
synthesize proteins
that are essential for
life.
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DNA stays in the
nucleus but RNA can
move from out of the
nucleus into the
cytoplasm.
Some RNA acts like a
messenger for DNA. It
delivers instructions for
making proteins at the
ribosomes.
Before a cell reproduces,
it’s chromosomes are
copied so that the new
cell has the same genes.
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Large molecules that
pass in and out of the
nucleus do so through
pores in the membrane.
Smaller particles can go
through the membrane
itself or through
membrane proteins.
Nucleoli are
chromosome parts that
are copies of the DNA
that codes for the RNA
present in ribosomes.
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Some plastids can be
found in plants and
algae. Some store
lipids and starches
and some have
pigments (color).
The most common
one is the chloroplast
which contains
chlorophyll and other
pigments needed for
photosynthesis.
Plant cell vs. animal cell (6:05)
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Lysosomes are vesicles
formed by the Golgi
body.
Lysosomes fuse with
vesicles containing food
and release enzymes to
break the food down.
They also digest worn
out cell parts.
The rest of the cell is
protected from the
enzymes by the
lysosome’s membrane.
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Peroxisomes protect
the cell from its own
production of
hydrogen peroxide.
For instance, a white
blood cell produces
hydrogen peroxide to
kill bacteria so the
lysosome will break it
down into oxygen and
water.
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Cell secretions like
hormones and
neurotransmitters are
packed in secretory
vesicles at the Golgi
Complex and then
removed from the
cell.
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Sometimes cells
produce substances that
they don’t need right
away.
Vacuoles are fluidfilled, membrane-bound
structures that store
these substances for
later use.
Many freshwater
protists have contractile
vacuoles used to
remove excess water.
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Proteins in a cell
manufacture long, thin
structures that give shape
and support to the cell.
Microfilaments are made
of actin and myosin
(proteins) that assist in cell
movement as well as
structure.
Microtubules provide
structures that can help
certain organelles like
mitochondria move
through the cytoplasm.
Actin and Microtubules (0:39)
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A ribosome is a cellular
structure on which
proteins are made. All
cells also have DNA, the
genetic material. DNA
provides instructions
for making proteins,
regulates cellular
activities, and enables
cells to reproduce.
Other ribosomes that
are attached to other
organelles are called
“bound” ribosomes and
make proteins that are
exported from the cell.
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The proteins produced
by cells have many
uses. The proteins that
are sent outside the cell
must be kept separate
from the rest of the
cytoplasm. To achieve
this separation, the cell
packages the proteins in
vesicles. A vesicle is a
small, often sphericalshaped sac that is
formed by a membrane.
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Rough ER
Has ribosomes
attached.
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Smooth ER
No ribosomes
attached.
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The Golgi apparatus is
the packaging plant of
the cell. It changes and
repackages proteins and
other protein products
that are in vesicles, then
transports them to the
plasma membrane
where they are released
out of the cell. The
vesicles then become
part of the cell
membrane.
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Plants have a central
vacuole that stores
water, ions, nutrients,
and wastes. It can
also store toxins or
pigments. When
water fills the central
vacuole, it makes the
cell rigid, allowing the
plant to stand upright.
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Other vacuoles can be
found in protists
which pump exess
water out of the cell.
Paramecium
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Centrioles, Cilia and Flagella (0:40)
In cells of animals, some
fungi and algae, two pairs
of centrioles play a role in
cell division.
Cilia and flagella are
flexible projections that
extend outward from the
cell, while still
surrounded by the cell
membrane. They are used
to move the cell around its
environment.
They are also found in
your lungs where the cells
don’t move, but the cilia
move mucus up and out
of your lungs.
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Prokaryotes were the first
cells. So where did
eukaryotes come from?
Symbiotic Theory states that
sometime during evolution,
prokaryotic cells became
symbiotic partners of other
cells which led to eukaryotes.
Evidence for this is that
mitochondria and
chloroplasts ( which are not in
the nucleus) contain their own
DNA, RNA and ribosomes.
It’s thought that these
organelles are what remains
of once free-living
prokaryotes.
Mitochondria: An Example of
Evolutionary Symbiosis (02:34)
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Euglena: mac122.icu.ac.jp
Microscope: en.academic.ru
1st Cell: library.thinkquest.org