golgi body peroxisomes.pptx

--

1. Welcome

2. Golgi Body, Lysosomes , Peroxisomes , Glyoxisomes : Origin,Chemical Composition,Structure & Function

3. Golgi Body Golgi complex was first describing by Camillo Golgi in 1890 in nerve cells of cat and owl. A network of stacked membranous vesicles present in most living cells that functions in the formation of secretions within the cell are known as Golgi apparatus. Composed – lamellae, tubules, vesicles and vacuoles. Structure: Is made up of several stack of parallel,flattened sac or cisternae . Many peripheral tubules and vesicles.

4. Function: Packaging of food materials such as proteins, lipids and phospholipids for transport to other cells. It secrete many granules and lysosomes . The golgi apparatus also protects against cell destruction known as apoptosis.

5. Lysosomes Lysosomes (hydrolytic particles) were called pericanalicular bodies, first discovered in 1949. The term Lysosome was first used by de Duve in 1955. Lysosomes are membrane bound organelles that are found mainly in the animal cells. Greek word ' lysis ' means destruction or dissolution or digestive and 'soma' means body. originated from golgi bodies. In plant cell they are bounded storage granules and contain hydrolytic digestive enzymes. Cell organelles with large number of digestive enzymes which are used primarily for digestion of intracellular substances and removal of excess or worn-out organelles, food particles and engulfed viruses or bacteria. Help in destroying dead cells from tissue.

6. Structure: Lysosomes are surrounded by a single membrane unique in composition. The membrane contains highly glycosylated lysosomal associated membrane proteins (LAMP) and lysosomal integral membrane proteins (LIMP). That constitute about 50% of all lysosomal membrane proteins. Function: Digestion of intracellular substances and foreign particles, which comes in the cell by pinocytosis and phagocytosis . Thus lysosomes act as a disposal system of the cell. To repair the damage to the plasma membrane. Lysosomes are also involved in programmes cell death, or autolysis . This is the reason why lysosomes are often called as ‘suicide sacs’ .

7. Peroxisomes Peroxisomes are membrane bound organelles, occurring in the cytoplasm of almost all eukaryotic cells. Also called Microbodies . Their existence was first discovered by J. Rhodin in 1954. They are found in nearly all eukaryotic cells Human cells may contain upto hundred peroxisomes depending on type of cell. They are called “ Peroxisomes ” because they are the site of synthesis and degradation of Hydrogen Peroxide [H2O2], a highly reactive and toxic oxidizing agent. 

8. Structure: They are particles of about 100- 500 nm in diameter. A lipid bilayer membrane surrounds which regulates what enters and exits the peroxisome . There are at least 32 known peroxisomal proteins, called peroxins , which carry out peroxisomal function inside the organelle. Peroxisomes have the thickest membrane of all organalles . It has a dense matrix that contain enzymes. More than 30 different enzymes are present in peroxisomes . Function: Detoxification of alcohol and other toxic compounds. Biosynthesis of plasmogens , ether phospholipids, which are necessary for normal function of brain and lungs. Synthesis of unsaturated fatty acids. Participates in the synthesis of cholesterol.

9. Glyoxisomes Glyoxysomes are specialized peroxisomes found in plants (particularly in the fat storage tissues of germinating seeds) and also in filamentous fungi. first discovered by Harry Beevers in 1961. Glyoxysomes possess the key enzymes of glyoxylate cycle ( isocitrate lyase and malate synthase ). Glyoxysomes are found in contact with lipid bodies in cotyledons or endosperm where fatty acids are being converted to carbohydrate (sugars) during germination.

10. Structure:  They have a single membrane. They have high equilibrium density in sucrose gradient centrifugation. Their matrix (internal content) is finely granular. Function: Allows seeds to use lipid as a source of energy to form shoot and root during germination. The lipid stores of germinating seeds are used for the formation of the carbohydrates that fuel the growth and development of the organisms. Glyoxysomes also functions in photorespiration and nitrogen fixation.

11. Peroxisomes : versatile organelles with diverse roles in plants Peroxisomes are small, ubiquitous organelles that are delimited by a single membrane and lack genetic material. In plants, peroxisomes are essential for growth and development and perform diverse metabolic functions, many of which are carried out coordinately by peroxisomes and other organelles physically interacting with peroxisomes . In this study showed that peroxisomes addressing areas such as the diverse proteome, regulation of division and protein import, pexophagy , matrix protein degradation, solute transport, signaling , redox homeostasis and various metabolic and physiological functions. MSU, United States of America Pan et al., 2020

12. Peroxisomes are extremely variable in number, appearance and protein content, and function collaboratively with other organelles in various metabolic pathways. In development and metabolism between monocots and dicots , peroxisomes probably perform monocot- specific functions that could be applicable to agriculture for the improvement of crop performance and vigor . MSU, United States of America Pan et al., 2020

13. Golgi-mediated synthesis and secretion of matrix polysaccharides of the primary cell wall of higher plants The Golgi apparatus of eukaryotic cells is known for its central role in the processing, sorting, and transport of proteins to intra- and extra-cellular compartments. In plants, it has the additional task of assembling and exporting the non-cellulosic polysaccharides of the cell wall matrix including pectin and hemicelluloses, which are important for plant development and protection. In this review, we focus on the biosynthesis of complex polysaccharides of the primary cell wall of eudicotyledonous plants. University of California, USA Azeddine et al., 2012

14. We present and discuss the compartmental organization of the Golgi stacks with regards to complex polysaccharide assembly and secretion using immuno -electron microscopy and specific antibodies recognizing various sugar epitopes . We also discuss the significance of the recently identified Golgi-localized glycosyltransferases responsible for the biosynthesis of xyloglucan ( XyG ) and pectin. University of California, USA Azeddine et al., 2012

15. References Singh,B.D . 2019. Genetics(3 rd edn .). Kalyani Publishers, New Delhi. https://www.ncbi.nlm.nih.gov/books/NBK9930/ . P.M.  Dey ,  J.B.  Harborne , 1997. Plant Biochemistry , The Plant, the Cell and its Molecular Components . Pan, R.; Liu, J.; Wang, S. and Hu , J. (2020). Peroxisomes : versatile organelles with diverse roles in plants.  New Phytologist.225 (4): 1410-1427. Driouich , A.; Chevalier, L.; Vicré , M. and Lerouxel , O. (2012). Golgi-mediated synthesis and secretion of matrix polysaccharides of the primary cell wall of higher plants.  Frontiers in plant science.   3 : 79.

16. THANK YOU