Download Homeostasis – process by which an organisms

NAME: _____________________________________ DATE: _____________ BLOCK: ____
THE BALANCING ACT OF LIFE
 Homeostasis – process by which an organisms maintains a relatively stable internal
environment
 Examples:
o Thermoregulation – maintaining body temperature
o Water regulation – keeping enough water in your body
o Regulating oxygen, blood sugar, and blood pH
PLASMA MEMBRANE
 Function: The plasma membrane encloses the cell and __________________ it.
 Function: It lets certain particles into and out of the cell.
 Surrounds all cells
MOVEMENT THROUGH THE MEMBRANE
 How do materials or substances enter or leave cells?
THE PLASMA MEMBRANE IS PICKY!
 Selective Permeability - the membrane can
_____________________________________ what particles can pass through it.
PLASMA MEMBRANE
 Plasma membranes are made of ________________________, proteins, and sometimes
cholesterol.
THE PHOSPHOLIPID
 A phospholipid - made up of a glycerol attached to 2 ___________________________
and a ________________________________ group.
 The fatty acids are ______________________________ (hate water).
 The phosphate group is ______________________________ (likes water).
Phospholipid
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THE BILAYER STRUCTURE
 The plasma membrane is a bilayer of phospholipids.
Plasma membrane
OTHER STRUCTURES IN THE MEMBRANE...
 Animal plasma membranes have cholesterol in between phospholipids to
_______________________their movement.
MEMBRANE PROTEINS
 Proteins are embedded in membranes.
 Some are on the inner or outer surfaces, some go the entire way through the bilayer.
MEMBRANE PROTEINS’ JOBS
 Regulate which particles can pass through membrane
(_____________)
 Act as _________________________________ in chemical reactions
 Act as _________________________________ on outside and inside
of cell to identify self
WAYS TO MOVE THROUGH THE MEMBRANE:
1. Active transport requires __________________________ to move the
molecules through the plasma membrane.
2. Passive transport does ____________ require energy, and occurs spontaneously.
PASSIVE TRANSPORT
 Types of passive transport
o Diffusion
o Osmosis
o Facilitated Diffusion
DIFFUSION
 The principle means of passive transport is diffusion.
 Diffusion is the movement of molecules from a _________________ concentration to a
____________________ concentration.
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
Diffusion occurs when a system is not at equilibrium and there is a difference in
concentrations.
FACTORS THAT AFFECT DIFFUSION:
 Temperature - higher temperature means more energy and molecules will diffuse
______________.
 Size - Smaller molecules will move ______________________________ than larger
molecules
REAL-LIFE EXAMPLES
 CO2 and O2 diffuse across plasma membranes.
 _____________________________ moves from an area of high
concentration to an area of low concentration from your lungs to your blood to your cells.
 As chemical reactions in the cell use up oxygen they produce _______________________.
 The concentration of CO2 inside the cell increases so that more CO2 is inside of the cell.
 Therefore CO2 _____________________ into your blood and then into your lungs where it
is exhaled.
OSMOSIS
 The movement of _______________________ from a _________________
concentration to a __________________ concentration.
 It is the ____________________________________ of water.
 This can cause cells to ______________________ or
______________________.
OSMOSIS IN PLANT AND ANIMAL CELLS
 In saltwater, animal cells ___________________and plant cells show _______________
(the insides of the cell shrivel, but not the cell wall).
 In freshwater, animal cells ________________ and plant cells _______________, but do
not burst due to large vacuoles and the cell wall.
OSMOREGULATION
 Saltwater organisms have to get rid of salt and conserve water.
 Freshwater organisms have to get salt and get rid of excess water.
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FACILITATED DIFFUSION
__________________________ diffusion along
 Proteins help certain chemicals pass through a plasma membrane
 Requires no energy (still moves from high to low)
 Usually needed for slightly larger molecules like glucose
ACTIVE TRANSPORT
 When a cell needs ______________________ to move molecules from
______________________ to ______________________ concentration.
 Proteins pump molecules through membrane.
 Molecules move ______________________________ diffusion (from low to high
concentration)
OTHER WAYS CELLS GET MATERIALS...
 Vesicles – a membrane-bound sac that is used to transport materials inside of a cell
 Endocytosis - plasma membrane ______________________________ and takes in
materials
 Exocytosis - vesicles with chemicals move to plasma membrane and fuse with membrane.
The chemicals are then __________________________________.
ORGANELLES AND TRANSPORT
 Some organelles are involved in moving materials within a cell.
 For example, proteins that are made in a ribosome often enter the rough ER. The rough
ER may modify the protein and transports it to the Golgi apparatus for processing and
packaging. The protein is packaged in a vesicle (sac) and delivered to where it is needed.
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