Lysosomes. Gr: lysis solution, soma body. Membrane bounded vesicles. Usually round ovoid or irregular electron dense bodies m.

Transcription

1 Lysosomes Gr: lysis solution, soma body Membrane bounded vesicles Usually round ovoid or irregular electron dense bodies m.

2 Lysosomes No. varies from a few to several hundred per cell, in different cell type Found in all cells except erythrocytes More in cells showing phagocytic activity e.g (macrophages, neutrophilic leucocytes)

3 Lysosomes Lysosomal enzymes synthesized and segregated in RER Transferred to Golgi complex Modified and packed as lysosomes

4 Has a large no. of hydrolytic enzymes (more than 40) Common enzymes are acid phosphatase, ribonuclease, deoxyribonuclease, proteases, lipases. Membrane of lysosomes separates them from cytoplasm & Preventing lysosomal enzymes from attacking and digesting cytoplasmic components. Lysosomes

5 Lysosome Functions Play an important role in protection against bacterial invasion As an exogenous material, when bacteria is engulfed it becomes phagosome

6 Lysosome Functions Lysosomes form cells garbage disposal system acting as an intracellular Digestive system Protein Carbohydrates Foreign materials Other molecules

7 Lysosome Functions Worn out (nonfunctional) cell parts are broken down by lysosomes Inactive resting lysosome is known as primary lysosome Active is known as secondary lysosome

8 Lysosomes Functions Undigestable material may persist known as residual body. Residual bodies may unite as large masses known as wear and tear pigments, Lipochrome pigments or lipofuscin pigment

9 Lysosomes Functions Lipofuscin is the name given to finely granular yellow-brown pigment granules composed of lipid-containing residues of lysosomal digestion. It is considered to be one of the aging or "wear-and-tear" pigments, found in the liver, kidney, heart muscle, retina, adrenals, nerve cells, and ganglion cells

10 Peroxisome Peroxi; some; Peroxi-- -Hydrogen peroxide Soma body.

11 Peroxisome Spherical, membrane bounded organelles m diameter Peroxisomes self replicate More in liver cells

12 Peroxisome Contain more than 40 enzymes Helps in clearing the cell toxic substances, particularly e.g hydrogen peroxide. Neutralize dangerous free radicals

13 Peroxisome Contain more than 40 enzymes Helps in clearing the cell toxic substances, particularly e.g hydrogen peroxide. Neutralize dangerous free radicals

14 Proteasomes Remove or digest unnecessary and harmful proteins as individual molecules( the major protein degradation machine in cytoplasm) where as Lysosomes digest bulk material introduced to cell or hole organelles and vesicles.

15 Seen only with E.M. Are a specialized form of SER membrane Annulate Lamellae (From cytology Atlas) Resembles the nuclear envelope, Is formed by stacks of parallel lamellae or cisternae containing many pores. Cisternae show pore complexes, like the nuclear pore complexes Annulate lamellae are more in cells with a high membrane turnover. such as tumor cells, testicular Sertoli cells and gametes.. Considered to be derived from the nuclear envelope, however the origin and function is not clear Details from a human oocyte E.M; magnification:

16 Vaults Recently discovered membrane bounded organelles. Exact function is not known, may form a covering around mrna. and Ribosome

17 Vacuoles Vacuus empty (any small space or cavity in protoplasm) Membrane bound storage areas for resources Named after the resource they contain e.g. food vacuole. Vesicles --- vesica,( bladder) a small bladder or sac containg liquid. A pneumocyte packed with cytoplasmic vacuoles

18 Cytoplasmic Inclusions Formed components in nucleus & cytoplasm are of two types Organelles and inclusions. Organelles are found in all cells Metabolically active with specific functions; are essential or indispensable and permanent. Inclusions are not found in all cell types Metabolically inert (less active), are non essential or dispensable and temporary e.g. pigment deposits or stored metabolites, lipids and carbohydrates.

19 Cytoplasmic Inclusions Lipids: stored mainly in the adipose cells Formed in SER R/Stains, lipid is dissolved and only round empty spaces are left Special stains e.g osmium tetraoxide fixation, shows lipid as a dark brown or black droplets.

20 Cytoplasmic Inclusions Glycogen: Mainly stored in liver and muscles E.M nm dense particles, more in areas with SER Stained with PAS (Periodic Acid Schiff) method, appears as magenta (purplish red) granules

21

22 Cytoplasmic Inclusions Pigments: materials with natural color i.e they do not require staining by dyes as do other cell components. Two types Exogenous: Found outside the body and then taken into it e.g carotenes, yellowish red pigments of vegetables fat soluble (lipochrome) Dust e.g carbon particularly in lungs and minerals e.g lead and silver pigments used in tattooing Inclusion with lamellar structure is found in a pneumocyte

23

24 Cytoplasmic Inclusions Endogenous are found in the body Melanin:hair,skin,eyes; melanocytes, melanosomes (from aminoacid tyrosine) Neurons of substantia nigra of brain, retina epithelium.

25 Hemoglobin: most abundant, break down products bilirubin and hemosiderin Lipofuscin; contained with in residual bodies yellowish brown fatty pigment (cardiac cells liver cells) Lutein: yellowish pigment found in cells of corpus luteum. Crystals: crystals and crystals like substances (crystalloids) probably proteinaceous e.g in sertolli cells and interstitial cells, as microbodies in liver. Cytoplasmic Inclusions