Transcript The Cell in its Environment

1
CELLULAR
TRANSPORT
The Cell and its Environment
Cellular Transport
2
The Cell in its Environment
3
The Cell Membrane
Selectively permeable membrane
Lipids
Transport
Proteins
4
5
SELECTIVELY PERMEABLE
6
Diffusion across cell membrane
Can it be an impenetrable boundary?
IN
food
carbohydrates
sugars,
proteins
amino acids
lipids
salts, O2, H2O
NO!
OUT
OUT
IN
waste
ammonia
salts
CO2
H2 O
products
cell needs materials in & products or waste out
7
Channels through cell membrane
inside cell
H 2O
NH3
salt
aa
sugar
outside cell
8
Cellular Transport
Two Kinds
1. Passive Transport
2. Active Transport
9
Types of Cellular Transport
Passive Transport - cell doesn’t use energy
Weeee!!
!
1. Diffusion
2. Facilitated Diffusion
high
3. Osmosis
Active Transport - cell uses energy
1. Protein Pumps
This is
gonna
2. Endocytosis
be hard
high
work!!
3. Exocytosis
low
low
10
PASSIVE TRANSPORT
Diffusion
Facilitated Diffusion
Osmosis
11
Passive Transport
Diffusion is the
movement of molecules
from an area of higher
concentration to an
area of lower
concentration.
12
Diffusion of Molecules
13
Diffusion
 Diffusion

movement from high  low concentration
14
Facilitated Diffusion
• Diffusion through protein channels
• channels move specific molecules across
cell membrane
facilitated = with help
open channel = fast transport
high
low
“The
Bouncer”
15
16
Passive Transport Comparison
Facilitated
diffusion
(Channel
Protein)
Diffusion
(Lipid Bilayer)
Carrier Protein
17
Osmosis
The movement of water across a
cell membrane
18
Isotonic
the
concentration
of water
outside and
inside the cell
is equal.
19
Hypotonic Solution
20
Hypotonic
the concentration of
water outside the
cell is greater than
the concentration of
water inside the cell;
water will flow into
the cell, causing it to
swell
21
Hypotonic Solution
Solute less
than Water
22
Water moves from the solution to inside of
the cell. The cell Swells and bursts open.
Cytolysis is cell bursting.
23
Hypertonic
the concentration of
water outside the
cell is lower than the
concentration of
water inside the cell;
therefore water will
flow out of the cell,
causing it to shrink
24
Hypertonic Solution
Solute greater
than Water
25
Water moves from inside the cell into the
solution and the cell shrinks.
Plasmolysis cell shrinking
26
Managing water balance
Cell survival depends on balancing water
uptake and loss.
27
28
Concentration of Solution
• Direction of osmosis is determined by
comparing total solute concentrations
Inside the Cell
Solution
Tonicity
Solute
Hypertonic

Water
Solute


Hypotonic


Isotonic
=
=

=
Movement of
Water
Water
(Cell Condition)

Water goes in
the Cell
(Cell Shrivel)

Water goes out
the Cell
(Cell Bust)
=
Normal Cell
29
How Organisms Deal with
Osmotic Pressure
Bacteria and plants have
cell walls that prevent
them from over-expanding.
In plants the pressure
exerted on the cell wall is
called turgor pressure.
30
How Organisms Deal with Osmotic Pressure
•A protist like paramecium
has contractile vacuoles
that collect water flowing in
and pump it out to prevent
them from over-expanding.
31
How Organisms Deal with Osmotic Pressure
• Salt water fish pump salt out of their
specialized gills so they do not
dehydrate.
• Animal cells are bathed in blood.
Kidneys keep the blood isotonic by
remove excess salt and water.
32
ACTIVE TRANSPORT
Protein Channels
Endocytosis and Exocytosis
Phagocytosis and Pinocytosis
33
Active Transport
 actively moves molecules to
where they are needed
 Movement molecules from
an area of low concentration
to an area of high
concentration (Low  High)
 cell uses energy
34
Types of Active Transport
Protein Pumps
Endocytosis
Exocytosis
35
Protein Pumps
transport proteins that
require energy to do
work
Sodium / Potassium
Pumps are important in
nerve responses.
36
37
Endocytosis:
taking bulky
material into
a cell
• Uses energy
• Cell
membrane
38
39
TWO KINDS:
1. Phagocytosis – cell enguls
solid particles of food
“cell eating”
2. Pinocytosis – cell takes in
droplets of fluid
“ Cell drinking”
40
Phagocytosis
Pinocytosis
41
3. Exocytosis: Forces
material out of cell in bulk
• membrane surrounding
the material fuses with
cell membrane
• Cell changes shape –
requires energy
• EX: Hormones or
wastes released from
cell
42
Cytoplasm