vacuoles

vacuolesMembrane-lined enclosures.Not permanentSimple animals make food vacuoles around the prey they engulf.In higher animals, white blood cells form vacuoles around engulfed pathogens.

Lysosomes Dark, spherical bodies in the cytoplasm (0.1-1.0m in diameter)Contain powerful mix of digestive enzymesFuse with the cell membrane and release its enzymes outside the cell.It can self- destruct (apoptosis or autolysis)

If an entire cell is damaged its lysosomes may rupture releasing its enzymes to destroy the entire content of the cell.They are also called suicide bags.FUNCTIONS:Digest the materials of the content.Digest worn out parts of the cell (autophagy).Release their enzymes outside the cells by exocytosis.

Cytoskeleton Feature of all eukaryotic cellDynamic three dimensional web like structure that fills the cytoplasm.Made up of microfilaments and microtubules.Many of the proteins in microfilaments are related to the contractile proteins in the muscle (actin, myosin)

Functions :

Gives the cytoplasm structure and keeps the organelles in place.

Closely linked with cell movements and transport within the cell.

Peroxisomes Small spherical membrane bounded bodies (0.5-1.5m diameter).Contain a number of enzymes.Mainly the enzyme which hydrolyses hydrogen peroxide.So these are called peroxisomes.Present mainly in actively metabolizing cells like liver cell.

ROLE OF RER AND GOLGI APPARATUS IN PROTEIN TRANSPORTThe ribosomes attached with the RER synthesize proteins.Poly peptide chains are released from the ribosomes.Pass through the membrane of the ERvesicles containing proteins pinched off from the ER.(transport vesicles)These vesicles fuse with the membrane sacs of the golgibody and the protein enters into it. Processing and packaging of protein occurs.

May be converted into glycoprotein, chromo protein, lipo protein, nucleoprotein, or enzymes or hormone protein.Secretory vesicles pinched off from the Golgi body transport the proteins to cell surface membrane.Enzyme or hormone is released from the cell by exocytosis.Digestive enzymes may be enclosed in vesicles to form lysosomes.

Relation between ER and GOLGI APPARATUS