(b)+Proteins+etc+(Q9-12)

(9) Distinguish between **integral** & **peripheral** proteins. ====

**Intergral**
====Proteins are protein that most of the molecules is found in between the phospholid molecules of the membrane; they interact with the cytoplasm on one side, with external molecules outside the cell and with the hydrophillic section of the membrane in between.====


 * Peripheral** proteins are protein that are mostly found outside the phospholid bilayer in the cytoplasm but interact with the phosphate heads; they may not be permanently associated with the membrane.

Q10. What is the key job of the proteins embedded in the plasma membrane?


 *  Integral proteins interact with the cytoplasm on one side and external molecules on the outside of the cell.
 *  The integral proteins have specific functions for carrying specific molecules in or out of the cell.

Functions of Membrane Proteins:
__//Hormone binding sites://__ //Hormones transported by the blood will only act on cells that have the appropriate protein receptor on the outside of their membrane.//

__//Immobolized enzymes://__ __//Cell adhesion://__ Intergral proteins can stick out and bind to specific proteins molecules in adjacent cells or they can bind to an extracellular matrix
 * Enzymes arranged into systems in order to make it easier for a sequence of reaction to occur. Example of this is the electron transport chain on the cristae of the mitochondrion**

__//**Channels for passive transport:**//__
They are often small proteins where the outside is hydrophobic and the inside of hollow tube is hydrophilic, allowing polar molecules to enter the cell ==== __//**Pumps for active transport:**//__ There are certain substances that normally would not be allowed by the cell membrane to enter the cell, however some specialized trans-membrane proteins may act as pumps to allow these substances into the cell on rare occasion. (see q.14) ==== (12) Distinguish between **active** and **passive** transport. **Active **transport requires a cell to use energy (ATP), while **passive** transport does not.

As powerful as diffusion is, cells must move materials in the opposite direction against concentration difference. **Active** transport occurs here as it requires energy to move small molecules or small ions across a cell membrane is generally carried out by transport proteins or pumps that are found in the membrane itself. Larger molecules and clumps of material can also be actively transported across the cell membrane by processes known as endocytosis and exocytosis.

(12) Distinguish between active and passive transport
** __Passive transport__ ** ** Require ATP? ** No ** The substances are transported: ** Small proteins, C2, O2, H2O, glucose…  ** The way to go in and out ** 1. Moving through the membrane (C2, O2…) 2. Moving through the special protein channel (H2O and Glucose)
 * Definition: ** The movement of the things from the region of high concentration to the region of the low concentration through the plasma membrane.
 * The role**: To balance the concentration of the inside and outside environment of the cell.

**Require ATP?** : Yes. As a result the process may go against the concentration gradient. The substances are transported: Na+, K+, ion… **The role**: To collect the stuff that the cell needs even when the concentration in the cell is higher than the outside environment
 * Active transport **
 * Definition: ** The movement of the things from the region of low concentration to the region of the high concentration through the plasma membrane.
 * The way to go in and out: ** Na+ and K+ go through the protein pumps with the push of ATP