Transcript Cell Transport Ppt

The Cell and Its Environment
Fall 2010
What is a cell?
A cell is the basic unit of living things.
Some living things are composed of only
one cell and are called UNICELLULAR
organsims.
Organisms that have many different cells
are called MULTICELLULAR organisms.
Homeostasis – Maintaining a
Balance
Cells must keep the proper
concentration of nutrients and
water and eliminate wastes.
The plasma membrane is
selectively permeable – it will
allow some things to pass
through, while blocking other
things.
What is the function of a cell?
* All living things obtain energy different
ways through the processes of
photosynthesis or respiration.
Since organisms must use energy
there are certain things that have to
get into and out of the cell to enable
the organism to use or convert
energy.
Materials that must be able to move INTO
ANIMAL cells:
1.Oxygen
 2. Water
 3. Particles of food
 4 Minerals and vitamns
for proteins(K, Na, Fe)
Materials that must be able to move OUT
of ANIMAL cells:
1. Carbon dioxide
2. Waste materials
Materials that must move INTO PLANT
cells:
1. Sunlight
2. Water
3. Carbon dioxide
Materials that must be able to get OUT of
PLANT cells:
Oxygen
Waste products
What lets stuff in and out of the cell?
Cell Membrane
Definition- a membrane that controls how
materials move into or out of a cell. It acts
as a gatekeeper to allow things in and out
Cell
of the cell.
Membrane
Overview
 Cell membrane separates living cell from
nonliving surroundings
thin barrier = 8nm thick
 Controls traffic in & out of the cell
selectively permeable
allows some substances to cross more easily than
others
 hydrophobic vs hydrophilic
 Made of phospholipids, proteins & other
macromolecules
What is a cell membrane?
 Cell membranes are the outside covering of a
cell that allows things in and out of the cell.
 Cell membranes are composed of 3 things:
 1. double layer of phosolipid molecules (fats)
 2. Proteins – moves large molecules.
 3. carbohydrate chains
 4. cholesterol
3 Types of Membrane Proteins
Transport large charged
molecules!!
 1.Receptor Proteins: Determine what
particles can pass through the membrane.
 2. Enzymes: Serve as enzymes (may
speed reactions).
 3.Transport proteins:moves substances
across the membrane.
 This moves K, Na, Fe, Water, amino acids
any charged particle.
Phospholipids – allows not charged
small particle through! Phosphate
Fatty acid tails –
hydrophobic
Phosphate group head -
Fatty acid
hydrophilic
Arranged as a bilayer
Aaaah,
one of those
structure–function
examples
Why does the phosolipid align in 2 layers?
Phosphate head – hydrophilic because it is
charged opposite of water and they attract each
other. They will be on the outside touching the
Water.
Fatty acid tail – hydrophobic because it has no
charge and is repelled by water that is charged.
They are pushed way from water and align on
the inside.
Molecules that can move through
phosolipid part of membrane
Oxygen, carbon dioxide !! ANY
PARTICLE THAT IS SMALL AND
NOT CHARGED!!!
ttp://www.teachersdomain.org/asset/tdc02_int_membraneweb/
Any particle that is charged cannot move
through membrane because of lipid charged
tails.
Function of Carbohydrates in Membrane
Attached to the membrane’s proteins act as
identification tags. This allows cells to tell
each other apart. A heart cell will have different
carbohydrates than a heart cell.
Function of cholesterol in Cell Membrane
Cholesterol strengthens the cell membrane.
Structure of the Cell Membrane
Outside of cell
Proteins
Lipid
Bilayer
Transport
Protein
Animations
of membrane
Go to structure
Section:
Carbohydrate
chains
Phospholipids
Inside of cell
(cytoplasm)
How does stuff get in and out of the cell?
The cell membrane is what allows stuff in
and out of the cell. The membrane is
selectively permeable.
Selectively permeableDefinition- means that some substances
can cross the membrane while others
cannot.
Polar heads
love water
& dissolve.
Non-polar
tails hide
from water.
Carbohydrate cell
markers
Proteins
Fluid Mosaic
Model
This model
describes the
structure of the
cell membrane!!
How do phosolipids control what can pass
through Membrane?
The hydrophobic tails will not let any substance
pass through that has a charge(ion)(hydrophilic).
Only substances that are not charged
(hydrophobic)can pass through. If they cannot
pass through the membrane, then they must go
through the must get in another way.
Fluid Mosiac Model of Cell Membrane
This model describes the structure of the cell
membrane because it acts likes a liquid.
1. The cell membrane is flexible not rigid. The
phosolipids move from side to side.
2. There are so many molecules that make up the
membrane that it looks like a mosiac.
Structure of the Cell Membrane
Outside of cell
Proteins
Lipid
Bilayer
Transport
Protein
Animations
of membrane
Go to structure
Section:
Carbohydrate
chains
Phospholipids
Inside of cell
(cytoplasm)
Cell Transport
To understand cell transport, you must
understand how molecules move.
All molecules move. Even solids vibrate.
Most of the cell environment is liquid.
Molecules want to reach EQUILIBRIUM!
Equilibrium – equal amount of molecules
everywhere(across cell membrane).
Diffusion
Movement of molecules moving from an
area of higher concentration to an area of
lower concentration.
Example: air freshener, perfume, food
cooking, food coloring in water.
Increase temperature; increase rate of
diffusion
Diffusion occurs in liquids and gases.
Which direction will molecules flow?
Concentration Gradient
Difference in concentration of molecules
that makes the molecules move. They
move from highest level to the lowest
level.
The greater the difference the faster the
molecules move.
Concentration Gradient
Diffusion video
http://video.search.yahoo.com/search/vide
o;_ylt=A0SO8ZpVTNdMKS8AS3H7w8QF;
_ylu=X3oDMTBncGdyMzQ0BHNlYwNzZ
WFyY2gEdnRpZAM-?p=diffusion&ei=utf8&fr2=tab-img&n=21&tnr=21&y=Search
How does stuff get in and out of the cell?
Substances that move into and out of a
cell do so by means of one of two
processes: PASSIVE TRANSPORT or
ACTIVE TRANSPORT.
Types of Cell Transport
No Energy
Passive Transport
Energy
Active Transport
Diffusion
Faciliated diffusion(osmosis)
Bulk transport
endocyotsis
exocytosis
Passive Transport
http://video.search.yahoo.com/search/vide
o;_ylt=A0PDoX1LTNdMKyoAZayJzbkF?ei
=UTF-8&p=passive%20transport&fr2=tabimg&fr=The Cell and Its Environment
2010.ppt
Passive Transport
Definition: is the movement of dissolved
materials across a cell membrane without
using the cells energy.
Energy required: NO
Type of Transport: PASSIVE
Diffusion or facilitated diffusion(osmosis)
Passive Transport
Diffusion – passive transport
 Definition: is the process by which molecules
move from an area of higher concentration to an
area of lower concentration(liquids or gases).
 Ex: If a bacteria lives in a pond, the water in the
pond contains oxygen molecules. The area
inside the bacteria cell has a lower amount of
oxygen than the pond. So, the oxygen
molecules outside of the cell will freely move into
the cell.
Diffusion CONT’D
Energy required: NO
Type of Transport: PASSIVE
Faciliated Diffusion- Type of Passive
Transport
Movement of molecules across the cell
membrane but using a carrier
molecule(protein)
NO ENERGY
Follows the same rules as diffusion but
these molecules cannot slip through the
phosolipid tails.
Osmosis – facilitated diffusion
Definition: is the diffusion of water
molecules across a selectively permeable
membrane(sometimes uses carrier
protein).
-Many life processes require water,
therefore; all cells must have the
appropriate amount of water in them to
function.
Energy Required: NO
Type of Transfer: PASSIVE
Osmosis – Type of Faciliated
Diffusion
Movement of WATER across the cell
membrane.
Cells are 75 – 90 % water so osmosis is
 an important process.
Water molecules will continue to move
until EQUILIBRUIM is reached.
NO ENERGY NEEDED!!
Click on link below to see the flow of
water during osmosis.
http://people.eku.edu/ritchisong/RITCHISO
/osmosis3.gif
What Makes Water Move?
It is determined by the type of
surroundings the cell is placed that
determines the concentration gradient
Solution: mixture in which molecules of
one substance are evenly dispersed.
Solvent: substance that makes up the
greatest part of the solution.(usually water)
Solute: substance dissolved in the
solvent.(K, NaCl, O Na, Amino acids)
Types of solutions cell can be placed
Isotonic
Hypertonic
Hypotonic
Isotonic
Concentration of solutes are EQUAL
inside and outside the cell.
Why do they give a person who is
dehydrated a saline(minerals and salt)
drip(IV) vs. distilled 100% water.
Hypertonic
Solutes on the outside of cell is higher.
Water leaves cell
This is why slugs shrivels up with salt.
Animals that leave in salt water have
adaptations to deal with the salt in the
water.
This is why you do not drink salt water.
How will road salt affect roadside plants?
Hypertonic Solution
Cells are
shrinking
because more
solute outside
so water
leaves cell.
Hypotonic
Concentration of solute is greater inside
the cell so water moves in.
Animal cell will burst.
Plant cells fill vacuole creates RIGOR!
This is what causes plant to stand up.
Hypotonic Solution
Hypotonic Blood Cells
What do cells look like when they have
too much or too little water?
Video – diffusion, osmosis &
solutions
http://video.search.yahoo.com/search/vide
o;_ylt=AgiX5UpIi9KIAFvWdkNyYsubvZx4?
p=diffusion&toggle=1&cop=mss&ei=UTF8&fr=yfp-t-701
Facilitated Diffusion CONT’D
Active Transport
 Sometimes cells need materials to flow the opposite
direction of the flow of diffusion. In this case the cell
would need to use ACTIVE TRANSPORT to carry these
materials in and out.
 DEFINITON: is the movement of materials a cross a cell
membrane against the gradient using cellular energy.
 The cell uses its’ energy so the transport proteins “pick
up” materials and “carry” them across the membrane.
 Examples of substances that are carried in and out of
the cell this way are: calcium, potassium, and sodium.
 ENERGY REQUIRED: YES
TYPE OF TRANSPORT: ACTIVE
Active Transport – the energy
changes the shape of the protein to
match the molecule
Once the molecule
is through the
membrane the
protein will change
its shape back!
http://video.search.yahoo.com/search/vide
o;_ylt=A0SO8ZrQT9dMlgEAXAD7w8QF;_
ylu=X3oDMTBncGdyMzQ0BHNlYwNzZW
FyY2gEdnRpZAM?p=active+transport&ei=utf-8&fr2=tabimg&n=21&tnr=21&y=Search
Bulk Transport – No energy
Particles too large to move through the
membrane.(Particle of food, proteins)
2 Types of Bulk Transport
1. Endocytosis
2. Exocytosis
Steps of Endocytosis
1. Molecules move into the cell by the cell
surrounding the particle and forming a
vacoule around it.
2.Once vacuole is in cell, lysosomes will
place digestive juices in the vacoule and
break up the food or particles.
Pinocytosis: liquid is surrounded brought
into cell.
Phagocytosis: solids are surrounded and
brought into the cell.
SOLID
LIQUID
Endocytosis
http://video.search.yahoo.com/search/vide
o;_ylt=A0SO8Z1uUddMelcAfjn7w8QF;_ylu
=X3oDMTBncGdyMzQ0BHNlYwNzZWFy
Y2gEdnRpZAM-?p=endocytosis&ei=utf8&fr2=tab-img&n=21&tnr=21&y=Search
Steps of Exocytosis
1. Opposite of endocytosis
2. Vacoule send to the cell membrane with
waste and particles and ejected out of
cell membrane.
Exocytosis
Exocytosis
http://video.search.yahoo.com/search/vide
o;_ylt=A0SO8ZrfUddMOygAFNj7w8QF;_yl
u=X3oDMTBncGdyMzQ0BHNlYwNzZWFy
Y2gEdnRpZAM-?p=exocytosis&ei=utf8&fr2=tab-img&n=21&tnr=21&y=Search
Types of Cell Transport
No Energy
Passive Transport
Diffusion
Faciliated diffusion
Bulk transport
endocyotsis
exocytosis
Energy
Active Transport