ENDOPLASMIC RETICULUM
(ER)
By Grace VanValey, Krystal Kallarackal, and
Oliver Baltay
WHAT IS THE
ER?
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The ER is an organelle within eukaryote cells.
The term Endoplasmic Reticulum means “network
within the cell” in Greek.
There are 2 types of ER, Rough ER and Smooth ER
that are interconnected through their membranes.
The organelle is made up of cisturne (in the form of sacs
and tubules) and inside their membranes the area is
called lumen.
The ER functions as a packaging system for the cell
making and transporting different molecules, as a
destroyer of toxic substances, and as a regulator of
muscle contraction.
THE ROUGH ER STRUCTURE
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Called “rough ER” because of the ribosomes that are
attracted to its membrane giving it a bumpy
appearance.
A ribosome puts amino acids together to form proteins
in a cell.
The ribosomes translate genetic code from the
nucleus into a sequence of amino acids which is why
the rough ER is connected with the neucleus.
The rough ER is a connected network of flattened sacs
called cisternae.
The membrane is made up of phospholipids and the
space within the ER is separated from the
cytoplasmic fluid.
ROUGH ER’S 1ST
FUNCTION
The Rough ER makes membrane which it adds to
itself and can be used in other places of the cell.
 The ribosomes insert protein (translated from the
genetic code) into the ER membrane and the ER
enzymes make phospholipids from the proteins.
 The phospholipids create a bi-layer which adds to
the membrane making it larger.
 Later this membrane can act as a transport
vesicle moving all around the cell.
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ROUGH ER 2ND
FUNCTION
When the ribosome assembles the polypeptide
chain out of genetic code, it inserts it into the ER
membrane, and the ER attaches chains of sugars
to the polypeptide to make glycoprotein.
 The ER membrane pinches off from the rest of
the ER and sends the chain out in a transport
vesicle to be used by the Golgi Apparatus or
moves to the cell membrane.
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The glycoprotein is about to be
pinched off by the ER
membrane.
Ribosome
attached to
the ER
membrane.
It is
currently
inserting a
polypeptide
into the
lumen.
The
glycoprotein is
packaged in
its own
transport
vesicle made
out of ER
membrane.
This vesicle
can travel
freely to
anywhere
needed in the
cell.
Lumen
(ER inside)
ER
membran
e
The chains are added to the
polypeptide (before leaving the ER)
thus creating glycoprotein.
SMOOTH ER
STRUCTURE
The smooth ER does not have
ribosomes attached to its
surface giving it a smooth
appearance.
 The smooth ER is in the shape
of interconnected tubes called
tubules that are also known as
cisternae.
 The smooth ER is
interconnected with the rough
ER through the membranes.
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SMOOTH ER
FUNCTIONS
The smooth ER creates lipids, such as fatty acids,
phospholipids, steroids and carbohydrates.
 The ER makes these lipids using the enzymes in
its membrane.
 The smooth ER also acts as a storage organelle,
storing calcium ions which are needed for muscle
contraction. The nerves signal a muscle cell in
which the calcium ions leak out and cause a
contraction of the cell.
 The smooth ER also stores steroids.
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FUNCTION OF SMOOTH ER IN THE LIVER
When the smooth ER is in the liver it has a
specific function regulating the amount of sugar
in the blood stream.
 It also helps to get rid of toxic substances in the
liver such as alcohol and drugs by producing a
specific enzyme that can detoxify your liver.
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WANNA LOOK IT
UP!?
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If you want to know more about the ER or don’t
understand what we’re talking about, go to pages
58-59 in our science book or visit any of the
websites on our bibliography!
BIBLIOGRAPHY
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http://www.cellsalive.com/cells/er.htm
http://library.thinkquest.org/C004535/endoplasmic_reticulum.html
http://www.biology4kids.com/files/cell_er.html
http://www.merriam-webster.com/medical/cisterna
http://www.bio.miami.edu/~cmallery/150/cells/ER.jpg
http://www.cartage.org.lb/en/themes/sciences/zoology/animalphysiolog
y/anatomy/animalcellstructure/EndoplasmicReticulum/EndoplasmicR
eticulum.htm
http://www.bioteach.ubc.ca/Bio-industry/Inex/
http://people.eku.edu/ritchisong/301notes1.htm
Campbell, Neil A., Lawrence G. Mitchell, and Jane B. Reece. Biology:
Concepts and Connections. 3rd ed. San Francisco:
Benjamin/Cummings, 2000. Print.
http://kconline.kaskaskia.edu/bcambron/Biology%20117/Cells.htm
http://biology.about.com/library/weekly/aa041300a.htm
http://imcurious.wikispaces.com/Midterm+Exam+2010+Review+P1
http://www.cytochemistry.net/cell-biology/ser.htm