Integral Membrane Proteins: The Secretory Pathway

2) The mRNA exits through the pores in the nuclear envelope and travels to the cytoplasm, where it then binds to ribosomes.

“Active transport, the protein transporter moves molecules against, or up, the concentration gradient” (McCance & Huether, pg. 29).

List three criteria cells use to select materials to enter or leave the cell. Then explain the role of each criterion in determining the type of transport a cell will use for different sized molecules. For instance, small molecules move across the membrane by diffusion, given they are moving with the concentration gradient.

The body has two faces, the cis face which fuses with incoming transport vesicles, and the trans face which excretes the secretory vesicles. The cis face fuses with vesicles coming from the ER effectively from many directions due to its convex shape, whereas the concave trans face can direct the secretory vesicles to their destination. When fusing with the cis face, the transport vesicles release their proteins to be absorbed for modification. Each cisternal layer of the Golgi body holds different enzymes which each modify the passing proteins in separate ways. Between the layers the proteins are moved through the gaps by small vesicles. When a protein has been modified correctly, it leaves the Golgi body via secretory vesicles which then carry the modified proteins to the cell membrane or another organelle. The proteins that are transported to the cell membrane are either excreted from the cell, or absorbed into the membrane to aid with its function. Some of the secretory vesicles which hold hydrolytic enzymes stay within the cytoplasm and function as lysosomes.

The function of the Golgi apparatus is to modify, sort, and package proteins and other materials from the endoplasmic reticulum for storage in the cell or secretion outside the cell.

Another vital component of the cell membrane are the integral proteins. Integral proteins are embedded within the phospholipid bilayer, these proteins are typically transmembrane proteins which means that one end extends to the exterior of the cell while the other connects to the interior. Integral proteins are

The golgi complex is a structure composed of flattened sacs known as cisternae. It is involved in the modification and packaging of proteins, the manufacturing of lysosomes and transport of products via vesicles. (Bailey, R, 2013)

The golgi packages and modifies proteins. The golgi is like Post Office because the post office packages mail and sends it places. The lysosome digests and gets rid of wastes. It

Every cell membrane incorporates a fluid mosaic model. The “mosaic” of protein molecules embedded in a lipid bilayer. It’s fluid as most proteins and lipid molecules drift through it. The membrane consists of a phospholipid bilayer embedded with various proteins. The proteins help to get polar/hydrophilic molecules through the plasma membrane. Polar molecules have difficulty passing thru the hydrophilic membrane. Nonpolar molecules however, easily pass thru. The proteins can be integral proteins, meaning they go all the way through the lipid bilayer or peripheral proteins that sit on the hydrophilic outer layer and wait for something to happen. The layers are somewhat fluid, allowing the proteins to move across them. See diagram below.

may be more complex and may involve a mechanism that is distinct from gamma secretase.

ECM many attach to the cell through other glycoproteins that then bind to membrane proteins called integrins

20) The protein inside the ER can be exported from the cell through a junction. A

Endocytosis is the general term that refers to a form of active transport in which the cell internalizes fluids, molecules, parts of its plasma membrane, particles and other extracellular components such as bacterias, by the invagination of the plasma membrane and the formation of vesicles through a process of membrane fission and budding.

The sheath and the tube extend across the inner membrane, the periplasm and the outer membrane in the donor cell until the outer membrane in the recipient cell. The sheath shrinks through a helical movement and the inner tube punctures the target cell in particular its outer membrane. However, this action allows the effector proteins and the toxin to release inside the cell. After the injection and deliver the proteins, the inner tube is dissociated and the sheath is degraded by ClpV ATPase enzyme. In addition to Hcp and VgrG proteins are released into the extracellular space as secreted proteins ( Basler et al,2012) .the whole process can start over

The endoplasmic reticulum (ER) is an essential organelle that is a major place for the biogenesis of cellular components including proteins, lipids, and carbohydrates and internal calcium storage. ER is primarily responsible for protein translocation, protein folding and protein post modification. Proper folding of protein in the ER is accomplished with the aid of ER resident proteins or enzymes such as chaperones. Binding of chaperones to