Download Chpt. 5 –Cells in Their Environment Vocabulary Term - Wiki

Chpt. 5 –Cells in Their Environment
Chpt. 5 –Cells in Their Environment
Vocabulary
Term
Definition
A membrane that allows only
selectively permeable
certain substances to pass
membrane
through it.
diffusion
The movement of particles from
an area of high concentration to
an area of low concentration.
concentration
gradient
A difference in concentration of
a substance between two areas.
osmosis
The diffusion of water across a
selectively permeable membrane
from an area of high water
concentration to an area of low
water concentration.
Mr. Wilson
Page 1 of 8
Chpt. 5 –Cells in Their Environment
turgor pressure
The outward pressure that is
exerted on a plant cell wall by
the cell contents when water is
taken in by osmosis.
endocytosis
The process by which a cell
moves large amounts of
material, or non-dissolved
particles, into its cytoplasm
from outside the cell.
phagocytosis
A type of endocytosis in which a
cell uses pseudopods to move
non-dissolved solid particles into
its cytoplasm from outside of
the cell.
exocytosis
The process by which large
amounts of material, or nondissolved particles, are moved
from a cell’s cytoplasm to
outside the cell.
Mr. Wilson
Page 2 of 8
Chpt. 5 –Cells in Their Environment
5.1 The Cell Membrane
The cell membrane is the “gatekeeper” of the cell. It
is a selectively permeable membrane that controls
what is allowed into and out of the cell.
The cell membrane is made up of two layers of
phospholipids (fat particles) that have many
proteins embedded in them. The proteins act
as channels through which materials can pass
in and out of the cell.
Mr. Wilson
Page 3 of 8
Chpt. 5 –Cells in Their Environment
Small particles (water, oxygen, carbon dioxide) can
pass easily through the cell membrane, while large
particles (sugars, fats) cannot.
Click here for more information about cell membranes.
5.2 Fluid Movement in Cells: Diffusion
Remember:
Particle Theory -all particles of matter are in
constant motion.
Concentration
Concentration
Gradient
-measure of the amount of a
substance that is mixed in with
another substance.
-refers to the difference in
concentration between two areas.
Mr. Wilson
Page 4 of 8
Chpt. 5 –Cells in Their Environment
Diffusion
-particles move from an area of high
concentration to an area of low
concentration. Click here or here for
a demonstration of diffusion.
Three particles small enough to move or diffuse freely
across a cell membrane are water, oxygen, and carbon
dioxide.
In the human body, oxygen diffuses from blood cells
into muscles where it is used as energy, and the waste
product, carbon dioxide, diffuses from the muscles to
the blood cells.
In living things, diffusion through the cell membrane is
how cells obtain nutrients (energy) and remove waste.
Mr. Wilson
Page 5 of 8
Chpt. 5 –Cells in Their Environment
5.3 Osmosis: An Important Type of Diffusion
Osmosis is the diffusion of water across a
selectively permeable membrane. This means only
certain particles are allowed to pass through the
membrane.
Osmosis occurs as a result of a concentration
gradient and ends when the concentration of water
on both sides of the membrane is equal.
For an example of osmosis, click here.
Mr. Wilson
Page 6 of 8
Chpt. 5 –Cells in Their Environment
Turgor Pressure:
As plant roots take up water, it is transported and
stored in the large, central vacuole of plant cells.
Turgor pressure is the amount of pressure placed on
the cell wall by the cell’s contents when water is
taken in by osmosis. A plant that is swollen with
excess water is said to be “turgid”.
Mr. Wilson
Page 7 of 8
Chpt. 5 –Cells in Their Environment
5.6 Endocytosis and Exocytosis
endocytosis
-is the process by which a cell takes
in large amounts of materials
(food), or non-dissolved particles
from the outside environment into
its cytoplasm.
phagocytosis
-is a type of endocytosis in which a
cell uses pseudopods to move the
material into its cytoplasm.
exocytosis
-is the process by which a cell
expels large amounts of materials
(waste), or non-dissolved particles
from its cytoplasm to the outside
environment.
For animation of the process, click here.
Mr. Wilson
Page 8 of 8