1. Medical biology cytology
Lec5
Farah Essa Alrawi
08/03/1439

2. 03/03/1439
by:Farah E. Ismaeel

3. Peroxisome Small membrane bounded organelle. Present in all cell type.
Named for their enzymes producing and degrading hydrogen peroxide (H2O2), which is potentially damaging to the cell.
Similar to lysosome but less dense and contain no hydrolytic enzyme but contain several types of oxidases and catalases enzymes
03/03/1439
by:Farah E. Ismaeel

4. Peroxisome
Oxidases is enzyme that oxidized various organic substance to form hydrogen peroxide highly toxic product
Catalase enzyme which eliminate excess hydrogen peroxide by breaking it down into water and oxygen molecule. These enzymes also inactivate various potentially toxic molecules, including some prescription drugs.
03/03/1439
by:Farah E. Ismaeel

5. Peroxisome
So that the peroxisome protect the cell from the cytotoxic product because the degradation of hydrogen peroxide occur in the same organelle
Very abundant in the cell of liver and kidney.
03/03/1439
by:Farah E. Ismaeel

6. 08/03/1439
Farah Essa Alrawi

7. Peroxisome Peroxisomes form in two ways:
Budding of precursor vesicles from the ER
Or growth and division of preexisting peroxisomes.
These organelles lack nucleic acids; their enzymes are synthesized on free cytosolic polyribosomes and bear a small signal sequence of amino acids at the carboxyl terminus. This signal is recognized by receptors located in the peroxisomal membrane and the proteins are imported.
by:Farah E. Ismaeel

8. 08/03/1439
Farah Essa Alrawi

9. Peroxisome disorders
Peroxisomal disoreders (Zellweger syndrome) is a rare congenital disorder , characterized by the reduction or absence of peroxisome in the cells of the liver, kidneys, and brain.
An individual's tissues and cells can accumulate very long chain fatty acids (VLCFA) and branched chain fatty acids (BCFA) that are normally degraded in peroxisomes.
03/03/1439
by:Farah E. Ismaeel

10. Peroxisome disorders
The accumulation of these lipids can impair the normal function of multiple organ systems. In addition, these individuals can show deficient levels of plasmalogens, ether-phospholipids that are especially important for brain and lung function.
08/03/1439
Farah Essa Alrawi

11. Ribosomes
Ribosomes are membrane naked organelles present in all cells types( prokaryotes and eukaryotes)
Ribosomes are small electron-dense particles composed of proteins and rRNA.
All ribosomes have two subunits of different sizes and act to catalyze the process of protein translation (Protein synthesis), so that is more abundant in protein secreting cells.
03/03/1439
by:Farah E. Ismaeel

12. 03/03/1439
by:Farah E. Ismaeel

13. Ribosomes
In eukaryotic cells, the rRNA molecules of both subunits are synthesized within the nucleus. Their numerous proteins are synthesized in the cytoplasm but then enter the nucleus and associate with rRNAs. The assembled large and small subunits then leave the nucleus and enter the cytoplasm to participate in protein synthesis.
03/03/1439
by:Farah E. Ismaeel

14. Ribosomes are often attached to the endoplasmic reticulum; but they also may occur free within the cytoplasm, either singly or in groups called polyribosomes or polysomes.
03/03/1439
by:Farah E. Ismaeel

15. Attached ribosomes are synthesis any proteins that packaged or release from the cells as secretary product
While free polyribosome synthesis protein that use within the cell such as enzymes of peroxisome and enzymes of glycolysis.
03/03/1439
by:Farah E. Ismaeel

16. Proteasomes
Proteasomes are very small abundant protein complexes composed of three subunits :
two regulatory particles and one core particle
Non membranous organelle that degrades some protein molecules that attached to Upiquitin protein by ATP dependent pathway.
03/03/1439
by:Farah E. Ismaeel

17. 03/03/1439
by:Farah E. Ismaeel

18. Proteasomes function Remove proteins no longer needed by the cell
Degrade excess enzyme, denatured or otherwise nonfunctional polypeptides
Remove proteins no longer needed by the cell
Provide an important mechanism for restricting activity of a specific protein to a certain window of time.
Destroy protein infected by viruses.
03/03/1439
by:Farah E. Ismaeel

19. Clinical application on proteasomes
Failure of proteasomes or other aspects of a cell’s protein quality control can allow large aggregates of protein to accumulate in affected cells. Such aggregates may adsorb other macromolecules to them and damage or kill cells.
Aggregates released from dead cells can accumulate in the extracellular matrix of the tissue. In the brain this can interfere directly with cell function and lead to neurodegeneration.
Alzheimer disease and Huntington disease are two neurologic disorders caused initially by such protein aggregates.
03/03/1439
by:Farah E. Ismaeel

20. lysosomes digest organelles or membranes by autophagy, proteasomes deal primarily with free proteins as individual molecules.
08/03/1439
Farah Essa Alrawi

21. 08/03/1439
Farah Essa Alrawi

22. MAKE A COMPARASIM BETWEEN LYSOSOME AND RIBOSOME
H.W.
MAKE A COMPARASIM BETWEEN LYSOSOME AND RIBOSOME
08/03/1439
Farah Essa Alrawi

23. Thank you
08/03/1439
Farah Essa Alrawi