By Mariah Ghant, Saori Ishizuka, and Monica
Lin
Definition

 The set of membranes found in eukaryotic cells that
carry out a variety of tasks in the cell
 Tasks include:
 Synthesis of proteins
 Protein transport
 into membranes and organelles
 out of the cell
 Metabolism and movement of lipids
 Detoxification of poisons
Major Parts of the
Endomembrane

 Nuclear Envelope
 Endoplasmic Reticulum
(Smooth and Rough)
 Golgi Apparatus
 Lysosomes
 Vacuoles
 Plasma Membrane
Nuclear Envelope
Function
Structure
 Encloses the nucleus  Double Membrane
 Separates its contents
from the cytoplasm
 Perforated by pore
structures
 Nuclear side is lined
with nuclear lamina
 Ribosomes on
cytoplasmic side
Endoplasmic Reticulum
Function
Rough ER
Structure
 Many proteins and
 Makes secretory
proteins (glycoproteins)
 Keeps proteins
seperated
 Makes transport
vesicles
 “Membrane Factory”
for the cells
phospholipids added to
its own membrane
 Has ribosomes
 continuous with
smooth ER
Endoplasmic Reticulum
Smooth ER
Function
 Synthesis of Lipids
 Metabolism of
Carbohydrates
 Detoxification of Drugs
and Poisons
 Stores calcium ions
 Lacks ribosomes
Structure
 Membranes system of
interconnected tubules
Golgi Apparatus
Functions
 Multiple interactions
with the product of the
ER (proteins):
 Modifies
 Stores
 Sends to multiple
destinations
 2 poles of Golgi stack:
 Cis face- receives vesicles
containing ER products
 trans face- dispatches
vesicles
Structure
  Consists of flattened
membranous sacs
(citernae)
Lysosomes
Functions
 Used in animal cells to
digest macromolecules
 Autophagy- process of
recycling the cell’s own
organic material
 Phagocytosis- process
of intracellular
digestion in amoebas
and small organisms
Structure
  Membranous sac of
hydrolytic enzymes
Vacuoles
Functions
 Their functions vary in
different cells:
 Food Vacuoles- fuses with
the lysosome during the
process of phagocytosis
 Contractile Vacuolespump excess water out of
the cell
 Central Vacuole- located
in mature plant cells;
holds important organic
compound reserves; main
repository of inorganic
ions
 Major role in the growth
of plants
Structure
  Membrane-bounded
vesicles
 Container shape
 Contains pigments that
color cells
Plasma Membrane
Functions
 Encloses the entire cell
 Protein secretion occurs
here after they’ve been
carried by transport
vesicles
Structure
  Thin layer of cytosol
between central
vacuole and plasma
membrane
Interactions

 The endomembrane interacts with the nucleus via
nuclear envelope
 The nuclear envelope is connected to the rough ER,
which encloses the nucleus
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Review

Nuclear envelope is connected to rough ER
Membranes and proteins produced by the ER flow in the form
of transport vesicles to the Golgi
Golgi pinches off transport vesicles and other vesicles that give
rise to:
 lysosomes
 other types of specialized vesicles
 vacuoles
Lysosome is then available for fusion with another vesicle for
digestion
Transport vesicle carries proteins to plasma membrane for
secretion
Plasma membrane expands by fusion of vesicles; proteins are
secreted from the cell
Video

http://www.youtube.com/watch?v=PASnAaulK-Y