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Published byAsher Sutton Modified over 9 years ago
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The Endomembrane System
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A series of membranes found in the interior of a eukaryotic cell. It divides the cell into compartments, channels the passage of molecules through the interior of the cell and provides surfaces for the synthesis of lipids and some proteins.
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The Endomembrane System One of the fundamental distinctions between eukaryotes and prokaryotes.
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The Endomembrane System 1.Nuclear Envelope 2.Endoplasmic reticulum (ER) 3.Golgi Apparatus 4.Vesicles (Vacuoles)
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Nuclear Envelope Double membrane Pores permit exit of ribosomal subuints Separates nucleoplasm from cytoplasm
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Endoplasmic Reticulum System of membrane channels continuous with outer membrane of the nuclear envelope.
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Rough ER is: Contiguous with the outer membrane of the nuclear envelope. Studded with ribosomes on the cytoplasm side.
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Function of Rough ER Protein synthesis and modification.
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Function of Rough ER 1.Protein synthesis and modification. 2.Membrane Synthesis 3.Distributes Transport Vesicles
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Destinations of Rough ER Proteins Exported from the cell Sent to lysosomes or vacuoles Embedded in plasma membrane
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Smooth ER Continuous with rough ER smooth No ribosomes (hence smooth)
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Function of smooth ER 1.Synthetic processesPhospholipidsSteroids Fatty acids 2.Forms transport vesicles 3.Stores Calcium 4.Detoxifies poisons
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Golgi Apparatus Delivery System Of the Cell Discovered in 1898 Named For Camillo Golgi
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Golgi Apparatus Stack of 3-20 slightly curved saccules. 1 to few (protists) 20 or more - animal cells Several hundred – plant cells
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Golgi Apparatus Receives protein-filled vesicles that bud from the ER. Vesicles fuse with membrane of Golgi apparatus cis face.
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Golgi Apparatus Proteins modified as they pass through (form glycoproteins) Move to outer (trans) face after modification. Vesicles form & move to different locations in cell. At plasma membrane, vesicles discharge contents as secretions.
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Vesicles Enzyme Storehouses Lysosomes – Intracellular digestion centers; bud from endomembrane system Microbodies Peroxisomes – Enzymes catalyze the removal of hydrogen atoms. Glyoxysomes –Found in plants. Enzymes convert fats into carbohydrates
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Lysosomes Lysosomes Intracellular digestion centers Lysosomes Produced by Golgi Membrane-enclosed vesicles Contains digestive enzymes (function best in acidic environment) Break down organelles Animation: Lysosome Formation Animation: Lysosome Formation
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Lysosomes Intracellular digestion centers Eliminates cells engulfed by phagocytosis. White blood cells use lysosomes to digest engulfed bacteria. Autodigestion Autodigestion - when lysosomes digest parts of cells. Apoptosis Apoptosis - programmed cell death, a normal part of development Tadpole tail absorption. Degeneration of webbing between fingers
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Peroxisomes Abundant in cells that metabolize lipids Detoxify alcohol in liver and yeast cells Forms hydrogen peroxide that is broken down to water and oxygen by catalase. RH 2 + O 2 R + H 2 O 2 H 2 O + O 2
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Glyoxysomes (Peroxisomes in plants) In leaves carry out reactions the uses up O 2 and releases CO 2 that can be used in photosynthesis In germinating seeds - convert oils into sugars used as nutrients by growing plants.
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Vacuoles Large membranous sac Larger than vesicles Store substances Vacuoles in protozoans include digestive vacuoles and water- regulating contractile vacuoles.
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Vacuoles In protozoans include digestive vacuoles and water-regulating contractile vacuoles.
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Vacuoles Plant cell vacuoles (usually one or two) more prominenet; water-filled and give support to cell. Plant vacuoles store water, sugars, salt, pigments, and toxic substances to protect plant from herbivores.
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