Transcript Homeostasis and Transport - Somerset Area School District

And Cell Structure
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Cells move molecules using different types of
passive and active transport
These differ from each other by whether or
not cells must use energy.
◦ Passive= no energy
◦ Active = use energy
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Passive transport —movement of substances
through a membrane that requires NO
ENERGY
Types:
◦ Diffusion —movement of molecules from high to
low concentration
◦ Osmosis —movement of WATER from high to low
concentration
◦ Facilitated Diffusion —assisted diffusion of large or
insoluble molecules through a cell membrane.
◦ Ion Channel Diffusion —movement of ions from
high to low concentration.
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Molecules move from high to low concentration.
◦ Move down their concentration gradient
◦ Molecules can move through semi-permeable membranes
◦ Continues until equilibrium is reached.
Molecules to large to diffuse
through the membrane must find a
channel pore to travel through
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Osmosis is the movement of WATER from high to
low concentration.
Depends on the concentration of solutes inside and
outside of the cell.
◦ Hypotonic Solution—solution outside the cell has a lower
concentration of solute molecules than inside. Water
moves into the cell. (Oh NO! She’s gonna blow!)
◦ Hypertonic Solution —a solution outside the cell has a
higher concentration of solute molecules than inside.
Water moves out of the cell. (Cell shrinks!)
◦ Isotonic Solution —a solution in which the concentrations of
solute molecules are equal on both sides of the membrane.
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Control of osmosis
◦ Contractile vacuoles
◦ Solute pumps
◦ Cell Walls
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Cytolysis —bursting of a cell due to osmosis.
Hypotonic
Isotonic
Hypertonic
Identify the pictures as a cell in an isotonic solution,
hypertonic solution and hypotonic solution
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Assisted diffusion of large or insoluble molecules
through a cell membrane.
Carrier Proteins help the molecules to move from
high to low concentration.
Glucose is transported to cells in this way.
http://www.ncbi.nlm.nih.gov/book
s/NBK9847/
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Several ions are vital to cells but cannot pass
through the cell membrane because they are
not soluble in lipids. They are:
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Sodium (Na+)
Potassium (K+ )
Calcium (Ca2+ )
Chlorine (Cl-)
They require specific ion channels to pass
through membranes
http://tantalusprime.blogspot.com/2008_02_01_archive.html
Many ion channels have gates that close or open in response
to three stimuli:
1. stretching of cell membrane
2. electrical signals
3. chemical signals
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Active Transport —movement of substances
through a cell membrane that REQUIRES
ENERGY.
Molecules move from low to high
concentration
( “up” their concentration
gradient).
The Carrier Proteins involved require energy
from ATP and are called Cell Membrane
Pumps.
Example: Sodium-potassium pump
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Movement of VERY LARGE PARTICLES into a
cell. The cell membrane pinches off to trap
the particle inside a vesicle which can then
transport the particle throughout the cell.
Two types of endocytosis:
Phagocytosis—movement of large particles
or whole cells
Pinocytosis—movement of fluids
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Movement of VERY LARGE PARTICLES out of a cell. Vesicles
bring particles to the cell membrane to be released.
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Cell—smallest unit of life
All living things are made of one or many cells.
◦ Unicellular
◦ Colonies
◦ Multicellular
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Cells come only from other cells.
Levels of organization are:
Cells
Tissues
Organ
Organ System
Organism
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Prokaryotes —cells without a nucleus or
membrane-bound organelles
◦ Include bacteria and archaebacteria
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Eukaryotes —cells with a nucleus and
membrane-bound organelles
◦ Include cells from plants, animals, fungi and
protists
http://www.phschool.com/science/biology_place/biocoach/cells/common.html
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Features common to both prokaryotic and eukaryotic cells
include:
◦ DNA —genetic material located in the nucleus of
eukaryotic cells and in the nucleoid region of
prokaryotic cells
◦ Plasma Membrane —outer boundary of cell
◦ Cytoplasm —all the material inside the plasma
membrane, (not including the nucleoid region or
nucleus). It includes a fluid part called the cytosol and
many organelles and other particules floating in it.
◦ Ribosomes —site of protein synthesis
http://www.phschool.com/science/biology_place/biocoach/cells/common.html
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Plasma Membrane —Phospholipid bilayer that
surrounds a cell. Controls what gets in and
out.
Phospholipids have hydrophilic heads and hydrophobic tails
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Embedded in the phospholipid bilayer are different
types of proteins for transport, identification and
binding.
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Cytoplasm —gel like substance that fills the
cell. Organelles float in cytoplasm.
Nucleus —control center of cell. Contains
DNA.
Mitochondria —powerhouse of cell. Site of
cellular respiration (where ATP is made).
Contains its own DNA.
Ribosomes —protein factories of cell. Can
float in cytoplasm or be attached to ER.
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Endoplasmic Reticulum —transport system of
cell. Make up a large part of the
endomembrane system. Rough (with
ribosomes attached) and Smooth (with no
ribosomes)
Golgi Apparatus —packaging center.
Receives proteins and lipids; modifies and
packages them into vesicles.
Vesicles —transport vehicles. Types:
Lysosomes, peroxisomes, glyoxysomes,
endosomes.
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Plant cells have all of the same structures
plus:
◦ Cell wall —made of cellulose
◦ Central Vacuole —to store water
◦ Plastids —including chloroplasts (contain their own
DNA), chromoplasts and amyloplasts.
http://gmgmesjwk.pbworks.com/f/ksjakja.bmp
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