3.2 The movement of Substances across the Plasma Membrane in Everyday life
Posted March 24, 2011
on:The effects of hypotonic, hypertonic and isotonic solutions on plant and animal cells
•The solution with higher solute
concentration is said to be hypertonic
(‘hyper’:more)
•The solution with a lower solute
•Solutions in which the concentration of solute are equal are said to be isotonic(‘iso’: equal)
Animal and plant cells in an isotonic solutions
Animal and plant cells in a hypotonic solutions
3. The large central vacoule expands, causing the cell to swell
4. In this condition, the cell is said to be turgid and firm as a result of the net flow of water into the cell
6. The swelling plant cell in a hypotonic creates turgor pressure within the cell. This pressure prevents the cell from taking I too
much water and bursting as an animal cell would
Animal and plant cells in a hypertonic solutions
In animal cell, there is a net movement of water from inside to outside of the cell.
This causes the cell to shrink.
In red blood cell, the cell shrivel and the plasma
membrane crinkles up.
The cell has undergone crenation.
In plant cell, water diffuse
out of vacuole through osmosis. Both vacuole and cytoplasm shrink and plasma
membrane pulls away from cell wall (plasmolysis). The cell becomes flaccid. The
flaccidity causes the plant to become limp and stem to drop (wilting). The cell can
deplasmolysed by immersing it back to a hypotonic solution.
Wilting of plant
As a result, water diffuses from the cell sap into the soil by osmosis and the
cell is plasmolysed. Water shortage in soil also causes the plant to wilt.
Food preservation
more hypertonic to the food and causes water to leave through osmosis. The
es dehydrated. Microbes loses water to the surrounding and dies.
here is the pictures about 🙂 take a view .
An illustration of water movement in hypertonic and hypotonic solution
Movement across the Plasma Membrane : The movement of substances across the plasma membrane:Passive and Active transport
Posted February 16, 2011
on:Passive transport:-
Diffusion – The movement of ions or molecules from regions of higher concentration to regions of lower concentration.
(Down a concentration gradient)
Factors influencing the rate of diffusion:-
a)Concentration gradient – Increased rate .
b)Membrane permeability – Increased rate.
c)Increased surface area – Increased rate.
d)Increased molecular weight – Decreased rate.
e)Increased thickness of membrane – Decreased rate.
Osmosis - Osmosis is the movement of water from a region of high water concentration to
a region of lower water concentration thought a semi permeable membrane.
Facillated diffusion – Movement of specific molecules across cell membranes through protein channels.
– Similar to simple diffusion but the rate of diffusion is greatly accelerated by the action membrane proteins that act as
carrier molecules and aid in diffusion.
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Active transport :-
a)Transport of a substance (protein) across a cell membrane against the concentration gradient.
b)Transport across a cell membrane which requires energy generated by the hydrolysis of some energy carrier (usually ATP).
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Movement of across the Plasma Membrane:The Structure and Function of Plasma Membrane.
Posted February 16, 2011
on:
1. Most of the plasma membrane contains phospholipids in a lipid bilayer
a. The polar ends are hydrophilic (dissolve in water easily) while the
fatty acid tails are hydrophobic (dissolve in water with difficulty).
2. Plasma membrane is more structurally complex than a lipid bilayer.
a. Numerous proteins are imbedded in the lipid bilayer that have
many different functions.
1) act as ion channels, as in nerve function
2) act as a receptor for a hormone/neurotransmitter
3) are carrier molecules for specific substances
4) docking proteins for vesicle identification
5) glycoproteins are markers for cell-cell identification.
3. Cholesterol embedded in the membrane provides membrane fluidity.
Welcome ~
Posted February 14, 2011
on:This is G6 : BioMyLife ,Biology here @ WordPress.com .