Download Interesting facts: • Many cells in the body use exocytosis to release

NPTEL – Biotechnology – Cell Biology
Interesting facts:
•
Many cells in the body use exocytosis to release enzymes or other proteins that
act in other areas of the body like secretion of the hormones glucagon and insulin,
or to release molecules that help cells communicate with one another more
directly through the products that they secrete like neurotransmitters.
•
The immune system also uses exocytosis to communicate information between
cells.
•
Both endocytosis and exocytosis involve active transport, that is, energy must be
expended to move particles against the concentration gradient.
•
Both endocytosis and exocytosis involve the formation of vesicles: endocytosis
forms them in order to take particles into the cell via the cell membrane and
involves a reduction in cell membrane area, as part of the membrane is pinched
off to form a vesicle; exocytosis forms them in order to expel things from the cell
via the cell membrane and results in an increase in cell membrane, as the vesicle
wall joins that of the cell membrane and is incorporated into it. Thus, the two
processes also serve to balance each other.
•
The vesicle fusion is driven by SNARE proteins process of merging the vesicle
membrane with the target one resulting in release of large biomolecules in the
extracellular space.
•
Ca2+ might control the exocytotic/endocytotic balance in plants.
•
Synaptotagmin I (syt1) is required for normal rates of synaptic vesicle endo- and
exocytosis.
Joint initiative of IITs and IISc – Funded by MHRD
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NPTEL – Biotechnology – Cell Biology
14. How the phagocytosis takes place in the immune system of cells?
15. Describe the uptake of cholesterol by the mammalian cells using receptormediated endocytosis.
16. What is protein trafficking? Explain with an example.
17. What is transcytosis? Explain with an example.
18. What are the two types of exocytosis? Explain with a schematic diagram.
References:
1. B. Lewin (2007); Cells; 2nd edition, Jones and Bartlett pubisher
2. B. Alberts , A. Johnson,J. Lewis (2002); Molecular Biology of the Cell; 4th
edition, New York: Garland Science
3. G.E.Kaiser
(2011);
The
innate
immune
system:
Phagocytosis;
http://faculty.ccbcmd.
edu/courses/bio141/lecguide/unit4/innate/phagoprocess.html
4. N.S. Parkar, B.S. Akpa, L.C. Nitsche, L.E. Wedgewood, A.T. Place, M. S.
Sverdlov, O. Chaga, and R.D. Minshall (2009); Vesicle Formation and
Endocytosis: Function, Machinery, Mechanisms, and Modeling; Antioxidants &
Redox Signaling; 11(6):1301-1312
5. G.M. Cooper (2000); The Cell: A Molecular Approach; 2nd edition, Sunderland
(MA): Sinauer Associates
6. M. Verhage, J.B. Sørensen (2008); Vesicle docking in regulated exocytosis;
Traffic, 9(9):1414-1424
Joint initiative of IITs and IISc – Funded by MHRD
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