The cell
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All living things are made up of small, individual units called __________________
Some organisms consist of __________________________-unicellular
others made up of ________________________________-multicellular
___________________ _______________ are carried on by cells
Two Basic cell types:
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____________________: lack membrane bound structures (nucleus) = bacteria
_____________________: present in all living things except bacteria; filled with organelles,
(membrane bound structures). NUCLEUS –most important
Cell Size:
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Small because of the __________________________________________
__________________________________________________________
Limited by _________________________________________________
Cell organelles
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Nucleus
Mitochondria
Golgi body
Lysosome
Vesicle
Ribosome
Endoplasmic reticulum
Cell membrane
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_________________________ the cell from its surrounding environment
____________________________________ of materials into and out of the cell
Makes it possible for cell contents to be __________________________
________________________ from environment
Maintains __________________________ homeo___________________
stasis_________________________
Structure of cell membrane
• Two layers, ___________________ made of _______ (fat) molecules
– Hydrophilic =
– Hydrophobic =
______________________is the major lipid found in the cell membrane.
A. Each molecule has a _______________and two______________________.
1. hydrophilic nature, the______________ will orient (point) toward water.
2. hydrophobic nature, the___________ will orient away from water.
B. Because a cell is bathed inside and out in a watery solution, the phosopholipid
molecules form two layers, a lipid bilayer.
C. ________________, a steroid, fits between the tails of the phosopholipid to
provide _________________
Proteins of the cell membrane
A. _____________________________ are located on the interior and exterior.
B. ___________________________________ are embedded in the bilayer.
1. Some I.P. extend across the entire cell membrane.
2. Some I.P. protrude only on one side or the other.
3. Some I.P. have ___________________ attached which serve to:
a. hold adjoining cells together.
b. act as a site where viruses can attach.
c. site where hormones can attach.
4. Some I.P. have channels or pores through which substances can pass.
5. Some I.P. bind to a substance on one side of the membrane and carry
it to the other side.
Integral proteins
• Transport or move substances through membrane
• Receptors are sites that bind special messenger molecules that tell cell to start or
stop some chemical activity
• enzymes
• Bind membrane to neighbor or other cell structures
Scientists use the term _________________ _______________ ________________
to describe the cell membrane.
1. Because of this fluidity, membrane proteins and lipids can move laterally
(side to side) within the bilayer.
DIFFUSION
THE MOVEMENT OF MOLECULES FROM AN AREA OF _________________________
___________________________________________________________________
WHAT DRIVES THE DIFFUSION PROCESS? ____________________________
THE CELL MEMBRANE IS: ____________________________________________
Nutrients and waste must pass through the cell membrane
PASSIVE TRANSPORT
EQUILIBRIUM
OSMOSIS
ACTIVE TRANSPORT