the plasma membrane homeostasis - phsbio - homecell...2/3/2015 anwar sohail mohammad 1 the plasma...
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2/3/2015 Anwar Sohail Mohammad
1
The Plasma Membrane
&
Homeostasis
GPS
SB1 (a) Explain the role of cell membrane
in maintaining homeostasis.
SB1 (d) Explain the impact of water on
life processes (i.e., osmosis,
diffusion).
Learning Targets 1. I can label the Structure of plasma membrane.
2. I can describe the functions of plasma membrane and
the role of its parts.
3. I can classify and explain two types of Homeostasis.
4. I can describe how diffusion and facilitated diffusion
takes place.
5. I can describe 3 types of Osmosis; and 3 types of
solutions.
6. I can determine the type of osmosis in real life
situations.
7. I can describe how vesicle mediated transport works.
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1. LT-2: I can describe the functions of plasma membrane and
the role of its parts.
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Phospholipid
molecule
Transport
Protein
Carbohydrate
Chain
Cholesterol
molecule
LT-1: I can label the Structure of plasma membrane.
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The plasma membrane is a thin, flexible boundary
between the cell and its environment, composed of the
phospholipid bilayer.
1. Phospholipid molecules
Chapter 7
A phospholipid molecule consists of a hydrophilic head
(phosphate group) and two hydrophobic tails (fatty acid
chains) connected by means of Glycerol backbone. Hydrophilic Head
Hydrophobic
Tail
LT-2: I can describe the functions of plasma membrane and the role of its parts.
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Fluid Mosaic Model
The phospholipid bi-layer is flexible.
It allows other molecules (like H2O, O2, CO2 etc.)
to “float” in and through the membrane;
therefore, this model is called “Fluid Mosaic
Model”.
Other Components
Proteins
Cholesterol
Carbohydrates
7.2 The Plasma Membrane
LT-2: I can describe the functions of plasma membrane and the role of its parts.
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Cholesterol prevents fatty acid tails from sticking
together.
Cellular Structure and Function
Carbohydrates identify Chemical Signals
7.2 The Plasma Membrane
Carbohydrate
Chain
LT-2: I can describe the functions of plasma membrane and the role of its parts.
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Proteins
Cellular Structure and Function
Transmit signals inside the cell
Act as a support structure
Provide pathways for substances to enter and leave
7.2 The Plasma Membrane
LT-2: I can describe the functions of plasma membrane and the role of its parts.
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Selective Permeability
Cellular Structure and Function
What does it do?
Chapter 7
Plasma membrane determines
1.What should enter the cell
and how much
2.What should exit the cell
and how much
Due to this, plasma
membrane is called
selectively permeable.
LT-2: I can describe the functions of plasma membrane and the role of its parts.
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How do things pass through it? 1. Small molecules like water, carbon dioxide,
oxygen etc. pass through the tiny gaps between
the spherical heads.
2. Larger molecules pass through channel proteins
3. Some other molecules pass through carrier
proteins by means of a mechanism called
“Facilitated diffusion”
#1 and 2 are called simple diffusion.
4. Another process called “Active transport” forces material across the
plasma membrane against concentration gradient.
LT-2: I can describe the functions of plasma membrane and the role of its parts.
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Cellular Transport
ACTIVE TRANSPORT
PASSIVE TRANSPORT
Cells need to take in or throw out materials like oxygen or
carbon dioxide gas, food particles or molecules of
chemicals or water to maintain Chemical balance in the cell
called homeostasis.
This refers to “Cellular Transport”.
It is of two types:
and
LT-3: I can classify & explain two types of Homeostasis.
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Osmosis
Diffusion
Facilitated Diffusion By means of transport proteins
Ex: Sodium Potassium Pump
Vesicle mediated Transport
Cellular Transport (Homeostasis)
PASSIVE TRANSPORT
Energy is not required
According to concentration gradient.
(High Concentration to low
concentration)
ACTIVE TRANSPORT
Energy is required in the form of ATP
Against the concentration gradient.
(Low Concentration to high
concentration)
LT-3: I can classify & explain two types of Homeostasis.
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Diffusion (Passive Transport)
• Diffusion is the net movement of a substance (liquid or gas) from an area of higher concentration to one of lower concentration.
• Ex: Air freshener quickly diffuses in the air.
• Dye spreads in the water and quickly distributes itself uniformly.
• Sugar diffuses in the water and make it taste sweet.
LT-4: I can describe how diffusion & facilitated diffusion take place.
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Semi permeable membrane
(Plasma membrane) Solute molecules,
High Concentration Solute molecules,
low Concentration
Diffusion Animation
In “Diffusion” Solute molecules move across a semi permeable
membrane from the region of high concentration to low
concentration until the concentration on either side becomes equal.
LT-4: I can describe how diffusion & facilitated diffusion take place.
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LT-4: I can describe how diffusion & facilitated diffusion take place.
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Facilitated Diffusion (Passive Transport)
• Large molecules like glucose can’t pass
through the plasma membrane.
• The protein molecules, called channel
proteins or Transport proteins or carrier
molecules, span and allow them to pass
through.
• This is called facilitated diffusion.
• Energy is not needed in the process.
Click HERE for Facilitated Diffusion animation (Its really cool)
LT-4: I can describe how diffusion & facilitated diffusion take place.
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Cellular Structure and Function Chapter 7 LT-4: I can describe how diffusion & facilitated diffusion take place.
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Osmosis (Passive Transport)
• Osmosis is the movement of a liquid
(most often assumed to be water, but it
can be any liquid solvent) through a semi
permeable membrane from a region of
low solute concentration to a region of
high solute concentration.
-:Continued
LT-5: I can describe 3 types of Osmosis & 3 types of solutions.
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Osmosis (Passive transport)
10 mg/L
sugar solution
15 mg/L
sugar solution
A B
More Concentrated Less Concentrated
Water
LT-5: I can describe 3 types of Osmosis & 3 types of solutions.
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Types of solutions (Hypertonic, Hypotonic and Isotonic)
Hypertonic solutions are those in which more solute (and
hence lower water potential) is present.
If a cell is placed in Hypertonic solution, water moves out of
the cell, this is called exosmosis.
Hypotonic solutions are those with less solute (again read as
higher water potential).
If a cell is placed in Hyportonic solution, water moves in to
the cell, this is called endosmosis.
Isotonic solutions have equal (iso-) concentrations of
substances. Water potentials are thus equal, although there
will still be equal amounts of water movement in and out of
the cell, the net flow is zero.
If a cell is placed in Isotonic solution, osmosis doesn’t take
place.
LT-5: I can describe 3 types of Osmosis & 3 types of solutions.
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Cellular Structure and Function Chapter 7 LT-5: I can describe 3 types of Osmosis & 3 types of solutions.
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Cells placed in Hypotonic and
Hypertonic solutions
(Hypotonic) (Hypertonic)
LT-5: I can describe 3 types of Osmosis & 3 types of solutions.
Learning check: Determine
Exosmosis/endosmosis/dynamic equilibrium
1. An ocean fish placed in fresh water tank._____
2. A fresh water fish placed in salt water aquarium. _____
3. A pond fish placed in fresh water aquarium. _________
4. Cherios soaking milk. _________
5. Raisins swell in water. ______________
6. Blood cells placed in distilled water __________
7. Blood cells placed in salt water. _____________
8. Celery placed in salt water shrinks over time _______
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LT-6: I can determine the type of Osmosis in real life situation.
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ACTIVE TRANSPORT
Active transport requires the cell to spend
energy, usually in the form of ATP. Examples
include transport of large molecules (non-
lipid soluble) and the sodium-potassium
pump.
LT-7: I can describe how vesicle mediated transport works.
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Vesicle-mediated transport When particles are so large that they cannot pass through
any carrier protein, then cells use vesicle-mediated
transport. Energy is required in the form of ATP.
LT-7: I can describe how vesicle mediated transport works.
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Vesicle-mediated transport
Animation
LT-6: I can describe how vesicle mediated transport works.
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Vesicle-mediated transport • Vesicles and vacuoles that fuse with the
cell membrane may be utilized to release or transport chemicals out of the cell or to allow them to enter a cell.
• Exocytosis When the cell removes something from the cell (Exo = Exit).
• Endocytosis When some thing is taken in (Endo = Taken in)
• Phagocytosis is the type of endocytosis where an entire cell is engulfed.
• Pinocytosis is when the external fluid is engulfed.
LT-7: I can describe how vesicle mediated transport works.