What's written here are my own thoughts. If you disagree with it, be professional and click the red X on the top right hand side. Please don't spam my C-box with vulgarities.
Tuesday, May 08, 2007 @ 00:39
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Introduction
Phospholipid bilayer= membrane.
Phospholipid bilayer has a charge polar head and non-polar head.
Polar head interacts with the aqueous environment.
Non-polar heads interact with the non-aqueous environment to form a hydrophobic interior.
Proteins are embedded randomly in the membrane to create a mosaic pattern.
Therefore membrane is made up of mainly lipids and proteins.
Functions
The cell membrane acts as a selective membrane. It permits the transport of materials in and out of the cell. It also serves to compartmentalize the cell from the external environment. Beetroot cells are red/pink in colour as the red pigments are found in the vacuoles of the cell. A membrane called the tonoplast covers the vacuole. It has the same functions as that of the cell membrane.
Effect of: Detergent
Detergent causes the lipids present in the membrane to be more soluble thus making the membrane more fluid. It also denatures the proteins present in the membrane as detergent is alkaline in nature. The alkaline nature of the protein disrupts the ionic bond present in the proteins. It causes the protein to unfold, thereby exposing the hydrophobic interior to the aqueous environment. The overall effect of this is the disruption of the function of the cell membrane. It loses it's function as a selective membrane and it cannot control the transport of materials in or out of the cell anymore. The tonoplast, which is the membrane that covers the vacuole is subjected to the same effects as that of detergent. As such, the red pigments present in the vacuole will leak out and stain the solution red/pink.
Effect of: pH
Extreme changes in pH will disrupt the ionic bonds present in the membrane. The protein will unfold, exposing the hydrophobic interior to the aqueous environment. The H+ present will also react with the phospholipid fatty acid present. Overall effect is the disruption of the function of the cell membrane. It loses it's function as a selective membrane and it cannot control the transport of materials in or out of the cell anymore. The tonoplast, which is the membrane that covers the vacuole is subjected to the same effects as that of detergent. As such, the red pigments present in the vacuole will leak out and stain the solution red/pink.
Effect of: Alcohol
Alcohol will disrupt the weak hydrogen bonds that hold the proteins of the plasma membrane in place. It also causes the proteins present in the membrane to be denatured.
I give up... This is just 1/8 of what we must write lah. Wtf. where got enough time to squeeze all this in during the one hour time period??? Wtf...
