Transcript Cellular Organelle

Cellular Organelle
Cell Wall
• Not found in animal
cells
• In plants, the cell wall
provides support for
the cell (no skeleton)
– Is made of cellulose, a
tough, stringy
macromolecule
http://www.research.umbc.edu/~marten/Research/cellwall.jpg
Cell Membrane
• Function: Control the movement of
substances in and out – this makes it
selectively permeable.
• Made mostly of phospholipids, which have
a hydrophobic tail and a hydrophilic head,
like this:
Head
Tail
Cell membrane, continued…
• These lipids form a “lipid
bilayer”:
• Bilayer is flexible, giving
the cell different shapes.
• Some chemicals stick out
of the bilayer to allow for
cell identification. Some
are proteins that act as
channels to allow big
molecules (like sugar) to
go through.
Cell membrane, still…
• Because the cell
membrane is so
flexible, and it has a
broken, disjointed
look to it, the model of
the cell membrane is
called:
The Fluid Mosaic
Model
Vacuole
• Sac filled with water and
nutrients
• Function in plants: To give
the plant support by
providing Turgor pressure
– When the vacuole is full, it
pushes the organelle towards
the cell wall, which expands
the cell and holds the plant
upright.
• High Turgor Pressure
http://io.uwinnipeg.ca/~simmons/images/vacuole.gif
– When the vacuole lacks
water, the plant wilts
• Low Turgor Pressure
Endoplasmic Reticulum (ER)
• Extensive membrane
system
• Rough ER, shown here, is
covered with ribosomes
– Function: Transports,
modifies and stores
proteins
• generally internal transport
• Smooth ER
– Function: Transport,
modification & storage of
lipids
• creates steroid hormones and
other macromolecules.
http://images.google.ca/imgres?imgurl=http://www.cat.cc.md.us/courses/bio141/lecguide/unit
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The Golgi Apparatus
• Flattened sacs
• Function:
– Create lysosomes and
other protein-filled
vesicles
– Stores, modifies &
packages protein for
transport
• The process of packaging
proteins happens through
endocytosis
http://137.222.110.150/calnet/cellbio/image/golgi%20&%20transport%20vesicles-electron%20micrographlabel.jpg
Active Transport: Two Types
• Endocytosis:
– Membrane wraps around proteins, then pinches
off.
– Always refers to a vesicle (protein sac)
ENTERING the cytoplasm.
• Exocytosis:
– The golgi apparatus receives the proteins from
the Endoplasmic Reticulum, packaged in vesicles
– The vesicle membrane merges with the GA
membrane, and releases the proteins into the GA.
– Always refers to a vesicle LEAVING the
cytoplasm
• See handout
Bio11 CD
WWW
Lysosomes
• Only found in animal cells!
• Vesicles filled with digestive
enzymes (proteins that speed
up reactions)
• Function:
– Breakdown food particles and
foreign objects like bacteria
http://hematology.im.wustl.edu/faculty/kornfeld/lysosome.gif
Ribosomes
• Found all over cell:
–
–
–
–
on Rough Endoplasmic Reticulum
in cytoplasm
in mitochondria
in chloroplasts
• Function:
– Provides a site for protein synthesis
http://cellbio.utmb.edu/cellbio/rer5.jpg
• Millions found in most cells.
http://www.ro
ckefeller.edu/
rucal/journey/
ribosomes.gif
END