In a bullet/outline form simply name the component (RNA, protein, membrane etc.)
ID: 303151 • Letter: I
Question
In a bullet/outline form simply name the component (RNA, protein, membrane etc.) used, in the order used, and where appropriate add a brief descriptor of that component. <- this should take no more than 1 line. Explain what happens at the category AND how the new lipid and protein transit to the next category again using a simple bullet/outline form. The categories are:
A. Before ER
B. At the ER and how it transports to the Golgi
C. At the Golgi and how it transports to the plasma membrane.
D. At the Plasma Membrane
Effectively you are starting with an mRNA in the cytoplasm and processing it all the way through Constitutive and/or Regulative exocytosis. Be sure to include where new lipids are synthesized and how they move with the protein. Don't forget to include the recycling of components when they occur.
Explanation / Answer
Before endoplasmic reticulum – RNA are translated to protein in ribosomes. Here, mRNA act as messenger RNA and carries the information for protein synthesis. tRNA decodes the information carried by messenger RNA and rRNA attaches to sequence of protein forming ribosome. Protein is synthesized using three-letter genetic code presenting amino acids for desired protein sequence. At endoplasmic reticulum and transfer to golgi apparatus – The proteins synthesized in ribosomes enter into ER membrane by a process of co-translational translocation. In ER, N-linked glycosylation of proteins is done which involves addition of sugar molecule to N-atom of amino acid in protein. Then proteins are folded using chaperons. Chaperon molecules avoid any misfolding, and prevent any incorrect or premature folding. Formation of disulphide bonds occur using enzyme protein disulphide isomerase. Also synthesis of membrane lipids occur including phospholipids and cholesterol. The proteins are then transported to cis Golgi network. This transportation is facilitated by the formation of transport vesicles, where these vesicles are then finally targeted and fused. Proteins are packed into transport vesicles to transport. At golgi and transfer to plasma membrane – Proteins are sorted on the basis of their destined pathway as to whether they move forward in golgi bodies or return back to ER. Proteins move through each compartment cisterna. Glycosylation of proteins occur in golgi bodies, and finally proteins are transferred to their destined path like lysozyme, or plasma membrane, by fusion of vesicles. At plasma membrane – When proteins reach plasma membrane for exocytosis, they get fused with the plasma membrane forming membrane proteins. These proteins help in cell signalling and ion transport.