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CELL MEMBRANE
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CELL SONG
4-2 PARTS OF THE EUKARYOTIC CELL
CELL MEMBRANE
•Selectively permeable
1. Membrane lipids
•both sides of cell surrounded by water; polar hydrophilic
phosphate heads orient themselves toward the water;
nonpolar, hydrophobic fatty acid tails make up the interior
of the membrane and orient themselves AWAY from water
•phospholipids form a bilayer;
• cholesterol also found among fatty acid tails
2. Membrane Proteins
• some are attached to inner or outer surface of
membrane –
peripheral proteins
• others embedded in the membrane and span membrane
– integral proteins
•integral proteins often have carbohydrates attached to
them on the exterior face of the cell – these function as
receptors, or for cellular recognition sites –
form “fuzzy coat” or glycocalyx
3. Fluid Mosaic Model
•membrane is fluid in nature and allows for
lateral movement of the lipids and proteins
ORGANELLES
•contained in the cytosol, a gelatin like fluid
containing ions, and organic molecules
1. Mitochondria
•site of ATP synthesis
•energy of ATP fuels most of the chemical reactions
in a cell
•surrounded by a double membrane; outer membrane
serves as a boundary and inner membrane is highly
folded to form cristae, which increase the
surface area available for chemical reactions that
occur in the mito
2. Ribosomes
• NOT surrounded by a membrane
• Made up of RNA and protein, assembled in
the nucleolus, shipped out through
nuclear pores and are found attached to the
endoplasmic reticulum (exported or become
inserted into membrane) or free floating
(proteins made on these remain in
the cell interior for use by the cell)
3. Endoplasmic Reticulum
•a system of membranous tubules and sacs that
function as an intracellular (within the cell) highway
•smooth ER synthesizes lipids and carbohydrates,
breaks down toxic substances
• rough ER makes proteins for export or proteins to
be inserted into membranes
4. GOLGI APPARATUS
A system of flattened stacks of
membranes that process, package and
secrete biomolecules for export
(proteins, lipids and carbohydrates)