1) The amino acid is taken into the cell by facilitated diffusion or active transport.
2) During protein synthesis by ribosome at the rough ER, the amino acid is added to the growing polypeptide chain, which eventually becomes anchored in the ER membrane.
3) In the ER, the protein may undergo chemical modification such as glycosylation, to form a glycoprotein.
4) ER vesicle carrying the protein buds off from the ER, travels towards the Golgi apparatus and fuses with the cis face of the Golgi apparatus.
5) As the protein travels through the Golgi apparatus through repeated budding and fusion of vesicle, it may undergoes further modification.
6) At the trans face of the Golgi apparatus, the modified protein is sorted and packaged, and eventually enters a Golgi vesicle which buds off from the Golgi apparatus.
7) The Golgi vesicle moves towards the plasma/cell surface membrane and fuse with it.
8) The transmembrane glycoprotein, which contains the radioactive-labeled amino acid, becomes part of the cell surface membrane.
2) During protein synthesis by ribosome at the rough ER, the amino acid is added to the growing polypeptide chain, which eventually becomes anchored in the ER membrane.
3) In the ER, the protein may undergo chemical modification such as glycosylation, to form a glycoprotein.
4) ER vesicle carrying the protein buds off from the ER, travels towards the Golgi apparatus and fuses with the cis face of the Golgi apparatus.
5) As the protein travels through the Golgi apparatus through repeated budding and fusion of vesicle, it may undergoes further modification.
6) At the trans face of the Golgi apparatus, the modified protein is sorted and packaged, and eventually enters a Golgi vesicle which buds off from the Golgi apparatus.
7) The Golgi vesicle moves towards the plasma/cell surface membrane and fuse with it.
8) The transmembrane glycoprotein, which contains the radioactive-labeled amino acid, becomes part of the cell surface membrane.
*EXTRA*
For more information about how transmembrane proteins are held in the membrane, you can view this animation: http://www.youtube.com/watch?v=7XTpe7TRQEk
Hey Ms Teong,
ReplyDeleteI didn't managed to catch structured question 2f's answer today.. Do we talk about the protein, which is non polar interacting with the hydrophobic parts of the cell membrane, the fatty acid chains, and the protein, which is polar reacting with both the aqueous environment and the phosphate heads?
Hi Celestine,
ReplyDeletefor Cell structure worksheet B on Membrane transport Structured Q2f, it is incorrect to phrase your answer as "the protein is nonpolar" and "the protein is polar". Instead, you should say that the protein is made up of residues with hydrophobic/nonpolar R groups (i.e. presence of aromatic rings or long hydrocarbon chains) and residues with hydrophilic/polar R groups that interact differently with the cell membrane.
To be more specific, for this question:
- one mark is allocated to stating that structure E is held in the cell membrane via hydrophobic and hydrophilic interactions.
- the next mark is for stating that the protein consists of hydrophobic residues that INTERACT with the hydrophobic region of the cell membrane, while the protein also consists of hydrophilic residues that INTERACT with the aqueous medium inside and outside of the cell.
Hope that this is clear!