Download Slayt 1 - benanbiology

CELL MEMBRANE
1. Surrounds and protects the cell
2. made of phospholipids, proteins, and some
carbohydrates (Fluid mosaic model)
3. Gives mechanical strength
4. Controls the movement of substances into
and out of the cell (selective permeability)
5.Cell membrane is very flexible and
semipermeable. Large molecules as protein
can’t pass through it but small molecules as
water can pass (*Neutral molecules, lipid
soluble molecules can pass more easily than
the others)
Proteins in or on the phospholipid bilayer
functions in the
 recognition(receptors),
 transport and
 Response
Carbohydrates or glycoproteins and glycolipids
give identity to the cell. (specificity)
Copyright © 2009 Pearson Education, Inc.
Hydrophilic
heads
Outside cell
Hydrophobic
region of
protein
Hydrophobic
tails
Inside cell
Proteins
Hydrophilic
region of
protein
Cell membrane: is Selectively permeable
Allows some molecules in and keeps
other molecules out
CELLULAR TRANSPORT TYPES
PASSIVE
Transport that
Transport
requires energy(ATP)
(requires no energy)
* Active transport
* Simple Diffusion
* Endocytosis (in)
* Facilitated diffusion Phagocytosis (solid)
* Osmosis
Pinocytosis (liquid)
* Exocytosis (out)
Types of Cellular Transport
Passive Transport
cell doesn’t use ATP energy
Weeee!!
!
high
low
Transports that use ATP
This is
gonna
be hard
work!!
high
low
1. PASSIVE TRANSPORT
• It is the movement of molecules from
high
concentration
to
a
lower
concentration.
• Molecules move by kinetic energy
• Energy isn’t used so it can be seen in
both living and non-living things.
A. PASSIVE DIFFUSION
• It is a kind of passive transport freely
through membrane or without membrane
until
each
part
becomes
equal
in
concentration.
• ex. Oxygen and CO2 diffusion.
• Small molecules can diffuse across the
cell membrane
• Diffusion stops when concentrations of
two regions are equal
• The molecules can move by their own
kinetic energy randomly.
2.FACILITATED DIFFUSION :
• Some small molecules pass membrane
through protein channels . This is called
as facilitated diffusion.
• Ex. Glucose transport and some aminoacids
• Facilitated diffusion speeds up the
normal movement of molecules from
higher
concentration
to
a
lower
concentration.
THE FACTORS THAT AFFECT DIFFUSION
1.Temperature:
Increases the speed of diffusion
2. Differences of concentrations between
two regions : Increasing of the differences
of concentrations between two regions ;
increases ( )the speed of the diffusion
3. The size of the molecules : Increasing of
the size of the molecules , decreases ( )
the speed of the diffusion
4. surface area for the diffusion:
•
•
•
•
•
Similarities Between Diffusion And
Facilitated Diffusion
ATP Energy isn’t used
They can be seen in every cell
Kinetic energy is used
From high to a lower concentration
Until equal concentration.
3. OSMOSIS
• It is the diffusion of water
through a semipermiable membrane.
A) ISOTONIC SOLUTION :
• The concentration of solute in the solution can
be equal to the concentration of solute in the
cells. The cell is in an isotonic solution.
(iso = same as normal)
( No diffusion ;No osmosis)
B)HYPERTONIC SOLUTION :
The concentration of solute in the solution can
be greater than the concentration of solute in
the cells. The cell is in an hypertonic solution.
(hyper = more than normal)
Cell lose water ( water moves out of the cell )
and it shrinks. This process is called ‘Plasmolysis’
C) HYPOTONIC SOLUTION :
The concentration of solute in the solution can
be less than the concentration of solute in the
cells. The cell is in an hypotonic solution.
(hypo = less than normal)
• When water moves into the cell, the cell swells.
The process is called ‘Deplasmolysis’
• OSMOTIC PRESSURE : It is the absorption
power of cells for water.
• Concentration of solute ; Osmotic pressure
(sugar,salt)
• Concentration of solvent ; Osmotic pressure
( water )
TURGOR PRESSURE:
It is the pressure of the cell contents against
the cell wall, in plant cells
Cell content becomes nearer to cell wall.
It provides firmness and rigidity
A
B
• EXAMPLE 1:
• If the solute (dots) in this diagram is
unable to pass through the dividing
membrane,
• What will happen to the solution
level? Why?
• Compare osmotic pressures of A
and B?
• Compare water amount of solutions
A and B?
EXAMPLE 2:
Normal cell is put into 3 different medium , each time it returns back to its
original state.
Normal state
Medium I
Medium II
Medium III
Normal
Plasmolysis
Turgor
By looking at the changes in the cell in each medium,
Draw a graphic for the osmotic pressures of the cell?
Osmotic
Pressure of cell
Normal
I
II
III
medium
EXAMPLE 3:
The changes in the water amount of a plant cell is shown with a graphic.
water
amount
I
II
III
IV
environment
What type of environment are they?
Compare the osmotic pressure of the environments I, II, III,
and IV?
• EXAMPLE 6: Answer true or false:
……. a. If a plant cell is placed in salt solution, the central vacuole will
shrink
……. b. If a red blood cell is placed in distilled water, it will shrink
……. c. If a plant cell is placed in distilled water, the cell membrane will
move away from the cell wall.
…… d. If a red blood cell is placed in a salt solution, salt will enter the
cells, giving them a strange appearance
…… e. When cell loses water, turgor pressure increases.
•
•
a)
b)
c)
d)
EXAMPLE 7: MULTIPLE CHOICE: Circle and/or fill-in the
answer(s) that best completes the sentence.
During diffusion molecules tend to move _____________________
up the concentration gradient
down the concentration gradient
from an area of lower concentration to an area of higher concentration
in a direction that doesn’t depend on concentration
DIALYSIS : It is a diffusion of solute
through a semipermiable membrane. (used
in kidney failure)