science

7. is the movement of
small particles across a
selectively permeable
membrane like the cell
membrane until
equilibrium is reached.
 These particles move
from an area of high
concentration to an
area of low
concentration.

8. Simple Diffusion
form of diffusion that does
not require the assistance of
membrane proteins.
Facilitated Diffusion
diffusion of solutes through
transport proteins in the
plasma membrane

9. • Examples of diffusion: spraying
aerosols, and perfumes.
• High concentration (inside of the
can)—the molecules are packed
tightly together….
• To a LOW concentration – when
sprayed, the molecules are
released to a more free
environment
• The particles SPREAD OUT

10.  Osmosis is a specific type of
diffusion; it is the passage of
water from a region of high
water concentration through a
semi-permeable membrane to a
region of low water
concentration.
 Semi-permeable membranes
are very thin layers of material
that allow some things to pass
through them but prevent other
things from passing through.
Cell membranes are an
example of semi-permeable
membranes.
Water diffuses across a membrane
from an area of high concentration
to an area of low concentration.

11.  Isotonic solution
 (iso = equal or the same as
normal). A red blood cell will
retain its normal shape in this
environment as the amount of
water entering the cell is the
same as the amount leaving the
cell.
 Hypertonic solution
 (hyper = greater than normal).
In this situation, the red blood
cell will appear to shrink as
the water flows out of the cell
and into the surrounding
environment.
 Hypotonic solution
 (hypo = less than normal). A red
blood cell in this environment
will become visibly swollen and
potentially rupture as water
rushes into the cell.

13.  Hydrophilic molecules, charged ions, and
relatively large molecules such as glucose all
need help with diffusion. The help comes from
special proteins in the membrane known as
transport proteins.
 There are several types of transport proteins,
including channel proteins and carrier proteins.
 Channel proteins form pores, or tiny holes, in
the membrane. This allows water molecules
and small ions to pass through the membrane
without coming into contact with the
hydrophobic tails of the lipid molecules in the
interior of the membrane.
 Carrier proteins bind with specific ions or
molecules, and in doing so, they change
shape. As carrier proteins change shape, they
carry the ions or molecules across the
membrane.

14.  Channel proteins
 form pores, or tiny holes, in the
membrane. This allows water
molecules and small ions to pass
through the membrane without coming
into contact with the hydrophobic tails
of the lipid molecules in the interior of
the membrane.
Carrier proteins
bind with specific ions or
molecules, and in doing so, they
change shape. As carrier
proteins change shape, they
carry the ions or molecules
across the membrane.

15.  Active transport is the
movement of molecules from
LOW to HIGH concentration.
 Energy is required as
molecules must be pumped
against the concentration
gradient.
 Proteins that work as pumps
are called protein pumps.
 Active transport mechanisms
require the use of the cell’s
energy, usually in the form of
adenosine triphosphate (ATP).

16. Two types of active processes are the active transport and vesicle transport
 Active transport
 involves molecules moving against
a gradient or other form of
resistance, such as from an area of
lower to higher charge. Active
transport is used by cells to
accumulate needed molecules
such as glucose and amino acids.
 Vesicular transport protein,
or vesicular transporter, is a
membrane protein that
regulates or facilitates the
movement of specific
molecules across a vesicle's
membrane.

17. Two types of active processes are the active transport and vesicle transport
 Primary Active transport
 directly uses chemical energy (such as
from adenosine triphosphate or ATP in
case of cell membrane) to transport all
species of solutes across a membrane
against their concentration gradient.
 Secondary Active transport
uses the energy stored in
these gradients to move
other substances against
their own gradients

18. 18
The sodium-potassium pump is a
mechanism of active transport that
moves sodium ions out of the cell and
potassium ions into the cells — in all the
trillions of cells in the body.
The sodium-potassium pump also
requires carrier proteins. Carrier
proteins bind with specific ions or
molecules, and in doing so, they change
shape. As carrier proteins change shape,
they carry the ions or molecules across
the membrane.
Sodium is the principal ion in the fluid
outside of cells.
Potassium is the principal ion in the
fluid inside of cells.

19. 19
Symport
 two substance
moves at the same
direction
Antiport
 two substance
moves in the
opposite direction

20.  Very large molecules
cross the plasma
membrane with a different
sort of help, called vesicle
transport.
Vesicle transport requires
energy, so it is also a form
of active transport.
There are two types of
vesicle transport:
endocytosis and
exocytosis.

21. Endocytosis is a type of vesicle
transport that moves a
substance into the cell.
When an entire cell or other solid
particle is engulfed, the process
is called phagocytosis (cell-
eating). When fluid is engulfed,
the process is called pinocytosis
(cell- drinking). When the
content is taken in specifically
with the help of receptors on the
plasma membrane, it is called
receptor-mediated endocytosis.

23. White Blood Cells,
which are part of
the immune system,
surround and engulf
bacteria by
endocytosis.

24. Exocytosis is a type of vesicle
transport that moves a
substance out of the cell.
Exocytosis is a type of vesicle
transport that moves a
substance out of the cell.
A vesicle containing the
substance moves through the
cytoplasm to the cell membrane.
Then, the vesicle membrane
fuses with the cell membrane,
and the substance is released
outside the cell