Cell organelles


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  • Depending on developmental stage and environment, #, size, enzymes, metabolic function, varies. Grow on sugar: small peroxisomes Grow on methanol: large peroxisomes that oxidize methanol Grow on FA: large and break down FA to AcetylCoA by  -oxidation
  • Cell organelles

    1. 2. The organelles of animal and plant cells are similar to each other except that __________ are present only in animal cells, and ___________ are present only in plant cells. ORGANELLES Animal and plant cells have organelles . Organelles compartmentalize functions within the cell.
    2. 3. MITOCHONDRIA <ul><li>Electron micrographs of cells show mitochondria as rod like structures. </li></ul><ul><li>0.5 μ ,m-1 μ m in diametre </li></ul><ul><li>7 μ m in length </li></ul>
    3. 4. BIOMEDICAL IMPORTANCE <ul><li>INNER MEMBRANE </li></ul><ul><li>Component of electron transport system. </li></ul><ul><li>Impermeable to most ions and large molecules e.g; H,Na,ATP,GTP ,Pyruvate,Citrate etc. </li></ul><ul><li>For transport special carriers are present e.g Adenine nucleotide carrier system(ATP-ADP Transport) </li></ul>
    4. 5. <ul><li>Complex II,Succinate dehydrogenase </li></ul><ul><li>Complex V,ATP Synthetase complex. </li></ul><ul><li>OUTER MEMBRANE </li></ul><ul><li>Permeable to all ions </li></ul>
    5. 6. <ul><li>Matrix </li></ul><ul><li>Inclosed by inner mitochondrial membrane. </li></ul><ul><li>Contain enzymes of: </li></ul><ul><li>Citric acid cycle </li></ul><ul><li>β oxidation of fatty acids </li></ul><ul><li>Amino acid oxidation </li></ul><ul><li>Urea and heme synthesis </li></ul>
    6. 7. <ul><li>NAD </li></ul><ul><li>FAD </li></ul><ul><li>ADP,Pi </li></ul><ul><li>Mitochondrial DNA </li></ul><ul><li>Circular DNA,has information for 13 mitochondrial proteins and some RNAs </li></ul><ul><li>Mitochondrial cytochrome P450 system </li></ul>
    7. 8. <ul><li>P450 system is involved in the hydroxylation of cholesterol to steroid hormones(placenta,adrenal cortex,ovaries and testes) </li></ul><ul><li>Bile acid Synthesis (liver) </li></ul><ul><li>Vitamin D formation(kidney) </li></ul><ul><li>Mitochondria plays a key role in aging.Cytochrome C component of ETC plays a main role in cell death and Apoptosis. </li></ul>
    8. 9. <ul><li>MITOCHONDRIAL DISEASES. </li></ul><ul><li>Fatal infantile mitochondrial myopathy and renal dysfunction. </li></ul><ul><li>MELAS(Mitochondrial encaphalopathy lactic acidosis and stroke) </li></ul><ul><li>Myoclonic epilepsy etc. </li></ul>
    10. 11. BIOMEDICAL IMPORTANCE <ul><li>ROUGH ER </li></ul><ul><li>Biosynthesis of proteins. </li></ul><ul><li>Special proteins called CHAPERONS are present ,involved in proper folding of proteins. </li></ul><ul><li>Protein glycosylation </li></ul>
    11. 12. <ul><li>SMOTH ER </li></ul><ul><li>Synthesis of lipids,cholesterol and steroid hormones. </li></ul><ul><li>Detoxification of endogeneous and exogeneous substances </li></ul><ul><li>Microsomal cytochrome P450 monoxygenase system(Xenobiotic metabolism) </li></ul>
    12. 13. <ul><li>Elongation of fatty acids </li></ul><ul><li>Desaturation of fatty acids </li></ul><ul><li>Omega oxidation of fatty acids </li></ul><ul><li>Synthesis of other organelles ,peroxisomes and lysosomes in association with Golgi Apparatus. </li></ul>
    13. 14. _________ ___________ GOLGI APPARATUS <ul><ul><li>Function: Packages, modifies, and transports materials to different location inside/outside of the cell. </li></ul></ul><ul><ul><li>Appearance: Stack of pancakes </li></ul></ul><ul><li>Consists of a stack of curved saccules. </li></ul><ul><li>Receives protein and also lipid-filled vesicles from the ER, packages, processes, and distributes them within the cell or for export out of the cell (secretion) . </li></ul><ul><li>Also encloses digestive enzymes into membranes to form lysosomes. </li></ul>
    14. 15. <ul><li>Golgi complex is the site for the formation of carbohydrate side chains of glycoproteins and mucopolysacchrides(GAGs) </li></ul><ul><li>It gives rise to acroblast of spermatozoa that is converted to acrosome.It contains lysosomal enzymes and proteinases invoved in the fertilization of ovum. </li></ul>
    15. 16. LYSOSOMES <ul><li>Extracellular digestion of both intracellular and extracellular substances. </li></ul><ul><li>Single limiting membrane. </li></ul><ul><li>Acidic pH 5. </li></ul><ul><li>They have group of enzymes called HYDROLASES.The enzymes destined to inter lysosomes has mannose at their ends,which change to manose 6 phosphate and enter into the lysosomes. </li></ul>
    17. 18. <ul><li>BONE REMODELING </li></ul><ul><li>An osteoclast breaks the bone matrix down into fragments by means of secreated acid and lysosomal hydrolases .It completes the breakdown by endocytosis and lysosomal digestion of the fragment. </li></ul>
    19. 20. <ul><li>LIPOFUSCIN. </li></ul><ul><li>Age pigment wear and tear pigment. </li></ul><ul><li>DISEASES OF LYSOSOMES </li></ul><ul><li>Release of lysosomal enzymes in response to ionizing rediations,some carcinogens,silca particles,dust,hypoxia,heat and certain drugs leading to cell death, mutaions in genome and malignancies. </li></ul><ul><li>Lysosomal storage diseases </li></ul>
    20. 21. PEROXISOMES <ul><li>First observed by electron microscopy in animal cells (1950s), then in plant cells (1960s) </li></ul><ul><li>Christian deDuve (1965) </li></ul><ul><ul><li>Isolated from liver cells by centrifugation </li></ul></ul><ul><ul><li>Called them peroxisomes because they generate and destroy H 2 O 2 </li></ul></ul>
    21. 22. <ul><li>Single membrane </li></ul><ul><li>Roughly spherical </li></ul><ul><ul><li>0.2 - 1.7  m </li></ul></ul><ul><li>Composition varies </li></ul>
    22. 23. BIOMEDICAL IMPORTANCE <ul><li>Rich in enzymes. </li></ul><ul><li>50 Enzymes have been demonstrated in them. </li></ul><ul><li>Proteins called PEROXINS are involved in the various stages of their production. </li></ul><ul><li>These are involved in the metabolism of lipids i.e.plasmalogens,cholesterol. </li></ul><ul><li>Involved in the β oxidation of very long and branched chain fatty acids. </li></ul><ul><li>Shortens the chain of cholesterol in the formation of bile acids. </li></ul>
    23. 24. <ul><li>Peroxisomes are involved in the production and detoxification of H ₂O₂ </li></ul><ul><li>PEROXYSOME PROLIFERATOR ACTIVATED RECEPTOR(PPARs). </li></ul><ul><li>PPARs α :expresses genes hepatic enzymes for β oxidation and formation of ketone bodies. </li></ul>
    24. 25. <ul><li>PPARs γ :express genes encoding for protein synthesis involved in lipid synthesis and storage in the fat cells. </li></ul><ul><li>PPARs δ :express genes encoding proteins of liver and muscles involved in the β oxidation of fatty acids and dissipation of free energy as heat. </li></ul>
    25. 26. Adrenoleukodystrophy: Deficiency in  -oxidation of very long- chain fatty acids Zellweger syndrome: Defect in protein import, giving rise to “ghost peroxisomes”
    26. 27. <ul><ul><li>An apparent amorphous mass enclosed by a nuclear envelope,Literally mean central core of the body or object. </li></ul></ul><ul><ul><li>Within: </li></ul></ul><ul><ul><ul><li>Chromosomes </li></ul></ul></ul><ul><ul><ul><ul><li>Chromatin </li></ul></ul></ul></ul><ul><ul><ul><li>Nuclear matrix </li></ul></ul></ul><ul><ul><ul><ul><li>Fibrillar network </li></ul></ul></ul></ul><ul><ul><ul><li>Nucleoli </li></ul></ul></ul><ul><ul><ul><ul><li>r-RNA and ribosomes </li></ul></ul></ul></ul><ul><ul><ul><li>Nucleoplasm </li></ul></ul></ul><ul><ul><ul><ul><li>Fluid of the nucleus </li></ul></ul></ul></ul>NUCLEUS
    27. 28. <ul><li>The nuclear envelope </li></ul><ul><ul><li>Components: </li></ul></ul><ul><ul><ul><li>Two cellular membranes </li></ul></ul></ul><ul><ul><ul><ul><li>Barrier to ions, solutes, macromolecules </li></ul></ul></ul></ul><ul><ul><ul><li>Membranes fused to form pores </li></ul></ul></ul><ul><ul><ul><ul><li>Complex assemblies of proteins </li></ul></ul></ul></ul><ul><ul><ul><li>Outer membrane </li></ul></ul></ul><ul><ul><ul><ul><li>Ribosomes </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Continuous with RER </li></ul></ul></ul></ul>
    28. 29. <ul><ul><ul><li>Inner membrane </li></ul></ul></ul><ul><ul><ul><ul><li>Bound to nuclear lamina </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Filamentous network </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><li>Nuclear lamina </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Supports envelope </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Attachment of chromatin </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><li>Nuclear lamina fibers </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Proteins – lamins </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li> superfamily – Intermediate filaments of cytoplasm. </li></ul></ul></ul></ul></ul>
    29. 30. <ul><li>The nuclear pore complex (NPC) </li></ul><ul><ul><li>Large numbers of proteins – synthesized in cytoplasm and transported into the nucleus </li></ul></ul><ul><ul><li>RNAs manufactured in nucleus – transported to cytoplasm </li></ul></ul>
    30. 31. <ul><li>NPC is made up of about 50 proteins called nucleoporins. </li></ul><ul><li>Show both selective and non selective movements of ions and substances. </li></ul><ul><li>Larger proteins(RNA polymerases)need special mechanisms to move from cytoplasm into the nucleus.Signal system…. </li></ul><ul><li>Expenditure of energy by GTP hydrolysis. </li></ul><ul><li>RNA move from nucleus to cytoplasm through these pores. </li></ul>
    31. 32. <ul><li>The nuclear envelope </li></ul><ul><ul><li>Components: </li></ul></ul>
    32. 33. <ul><li>The nuclear pore complex (NPC) </li></ul>Eukaryotic Nucleus - Structure
    33. 34. Chromatin <ul><li>Represents substance of chromosomes. </li></ul><ul><li>Each chromatid in a chromosome represents one DNA molecule that occurs in a highly condensed form. </li></ul><ul><li>The nucleic acids present in the chromatin is mostly DNA but small ammount of RNA is also present. </li></ul><ul><li>Chromatin is a combination of DNA and protein. </li></ul><ul><li>The most abundant proteins are histones(5 types),NUCLEOSOMES. </li></ul><ul><li>Other proteins include enzymes like DNA and RNA polymerases,Protins involved in the regulation of DNA transcription and replication. </li></ul>
    34. 35. <ul><li>Chromatin occurs in two forms, </li></ul><ul><li>Euchromatin </li></ul><ul><li>Stains lightly,partially or completely </li></ul><ul><li>uncoiled,active transcription. </li></ul><ul><li>Hetrochromatin </li></ul><ul><li>Stains deeply,highly coiled,generally </li></ul><ul><li>inactive include noncoding </li></ul><ul><li>regions,telomere and centromere. </li></ul>
    35. 36. <ul><li>Constitutive heterochromatin </li></ul><ul><li>Facultative </li></ul><ul><li>X chromosome inactivation, bar b0ody. </li></ul>
    36. 37. NUCLEOLUS <ul><li>Also called micronucleus. </li></ul><ul><li>Nucleolonema,network of </li></ul><ul><li>Strands containing RNA. </li></ul><ul><li>Size varies depending </li></ul><ul><li>upon the activity. </li></ul>
    37. 38. <ul><li>Nucleoli are formed around specific genetic loci called nucleolar organizing regions (NORs). </li></ul><ul><li>Consists of two parts. </li></ul><ul><li>Fibrillar part.(site for rRNA transcription).Genes for 28s,18s and 5.8s are located there. </li></ul><ul><li>Granular part.(assembly of ribosomal subunits takes place there). </li></ul>