Membranous organelles _ae3cce61e2489715d54067c6313e1a8a (1).pdf

Dr. Rania Ibrahim Yassien  Professor of Histology and Cell Biology  Head of Measurement and Assessment unit  Learning Objectives By the end of this Lecture, you should be able to:  Define histology & name the basic types of tissues.  Identify components of the...

Dr. Rania Ibrahim Yassien  Professor of Histology and Cell Biology  Head of Measurement and Assessment unit  Learning Objectives By the end of this Lecture, you should be able to:  Define histology & name the basic types of tissues.  Identify components of the cytoplasm.  Compare membranous and non-membranous organelles.  Identify the molecular structure of the cell membrane.  Correlate the molecular structure of the cell membrane with its functions.  Identify the microscopic picture (L.M &E.M) of mitochondria.  Correlate the structure of mitochondria with their functions. 4  What is the meaning of histology ? (Histo = tissue, Logia = branch of learning) Histology means study of microscopic structure of the cells, tissues and organs  4 3 1 Human body 2  LM What is the meaning of Cytology ? Cyto = cell, Logia = branch of learning EM the basic structural & functional unit of the living body. 5  Non-membranous Membranous Organelles CELL (E/M) Organelles Cytoplasm Inclusions Lysosomes Cell (E/M) Peroxisomes Centrioles Cell membrane Lipid Golgi complex Ribosom es Nucleus & nucleolus Glycogen Microfilament Mitochondria Site. LM Structure EM RER ER Chem.C. Functions. Microtubule Modifications. C.V. SER s Faculty of Medicine 7 1. Organelles 2. Inclusions  Living  Non-Living  Permanent  Temporary  Essential  Not essential except??  Active  Inert  Have vital functions  Metabolic products 3. Cytosol  Semifluid cytoplasmic matrix Faculty of Medicine 8   Covered by membrane  Uncovered by membrane  Cell (Plasma) membrane  Ribosomes  Mitochondria  Cytoskeleton  Rough endoplasmic reticulum (rER)  Smooth endoplasmic reticulum (sER)  Golgi apparatus  Lysosomes 9 membranous organelles  Tr ilaminar appearance  The limiting membrane of the cell.  Other names: Plasma membrane or Plasmalemma  H&E: Difficult to be seen; Very thin (8-10 nm). Ag  SP. stain: Ag & PAS  2 electron-dense (dark) layers separated by electron-lucent (light) zone.  Cell coat (glycocalyx): on the outer surface only. 11  Each phospholipid molecule has: Heads Tails (phosphate group) (Fatty acids) Charged Non-charged Polar Non-polar Hydrophilic Hydrophobic Directed towards  Directed inwards to the aqueous solutions center facing each other away from aqueous solutions Selective per meability of cell membr ane; 12  cell membrane appears trilaminar by EM? Due to deposition of osmium on the hydrophilic heads 14  Fill gaps between the hydrophobic fatty acid tails.   Stability of the membrane. (Restricting movement of phospholipid molecules)  Modulating membrane fluidity. 15  Small molecules.  Larger molecules.  Loosely attached to both surfaces of  Firmly attached to cell cell membrane. membrane.  Outside the lipid bilayer.  Embedded in the lipid bilayer. 16  Some proteins are partially embedded in the lipid bilayer.  Other proteins extend across the cell membrane from side to side (Transmembrane proteins). 17  oligosaccharide chains linked to:  Membrane proteins:  Membrane phospholipids:  located on the outer surface only of plasma membrane. 18 Faculty of Medicine 20  Active movement of substance into the cell by forming vesicles.  Active movement of substance from inside to outside of the cell by forming vesicles 21 22  (Cell eating) extended from the cell membrane to surround solid particle e.g. bacterium.  Ends of pseudopodia fuse enclosing bacterium in intracellular vacuole called.  Phagosome then fuses with for digestion of its contents.  Ex: WBCs engulfing bacteria. 23  (Cell drinking) (pocket) of cell membrane formed to surround extracellular fluid.  Ends of pocket fuse then detach off inwardly from cell membrane forming  Pinocytic vesicle then fuses with for digestion of its contents.  Ex: endothelial cells of blood vessels. Faculty o f 24  (Integral proteins) accumulate at the cell membrane to bind specific ligands.  They associate with other proteins on the cytoplasmic side called  The coated pit invaginates gradually and pinches off, forming containing ligands and their receptors. is dissociated and.  Ex: uptake of hormones as GH & uptaFkaceultyooffMeLdiD cineL. 25  Dwarfism Caused by GH deficiency OR Non-functioning GH receptors at cell membrane of target cells (Level of GH is normal)  migrates & fuses with the cell membrane.  Release of contents into extracellular space. 27   Membranous organelles responsible for cell respiration & energy production. (Power-houses of the cell)..  More in active cell as liver cell (1000/cell). L.M.: H&E: Cytoplasmic acidophilia (If abundant). (Large number of basic membrane proteins)  SP. stain: appear as granules or rods with Fe Hx & Janus green stains. E.M.:  Oval or rounded vesicles.  Surrounded with two membranes separated by intermembranous space. Outer membrane Inner membrane  Smooth & porous  Folded into Cristae  Contains transmembrane  surface area for attachment proteins called Porins of "ATP synthase“ enzyme (forms ATP in oxidative phosphorylation)  Permeable to small molecules  less permeable (selective)  E.M.:  The mitochondria, is filled with semifluid called Matrix; contains: - Oxidative enzymes of citric acid cycle. - Mitochondrial DNA , RNA & few ribosomes. - Dense granules rich in Ca2+ (catalysts). produce ATP. by simple fission. (Mitochondria can synthesize some of their structural proteins by their own DNA & RNA)  Mitochondrial Myopathies  Defect in mitochondrial enzymes leads to failure to produce ATP which is needed for all vital activities e.g muscle contraction leads to muscular weakness.  Mitochondrial DNA is always inherited from the mother 31  Functions: 1) They are the respiratory apparatus of the cell, concerned with the release of energy due to their content of oxidative enzymes (powerhouse of the cell). 2) They can form proteins for themselves, as they contain DNA and RNA and are capable of self-replication(division). 3) They are concerned with concentration of ions as ca. 4) They are strongly related to heat production in the brown fat of newborn. 1. Which of the following are essential for the vitality of a cell? a) Cytoplasmic inclusions b) Membranes c) Organelles d) Vacuoles 2. What is the function of the mitochondria in cells? a) Protein synthesis b) Energy production c) Waste disposal d) Structural support 3. What is the glycocalyx? a) The lipid bilayer of the cell membrane b) A layer of glycoprotein and glycolipid on the cell surface c) A structure in the nucleus d) A component of the cytoskeleton 4. Which of the following organelles contains DNA? a) Rough endoplasmic reticulum b) Smooth endoplasmic reticulum c) Mitochondrion d) Annulate lamellae 5. Which of the following organelles responsible for selective diffusion? a) Mitochondria b) Cell membrane c) Lysosome d) Rough endoplasmic reticulum 6. This organelle can be stained by: a) sliver b) Bests carmine. c) Janus green. d) Van gieson 7. What process is nicknamed "cell drinking"? a) Endocytosis b) Exocytosis c) Pinocytosis d) Phagocytosis 8. What is the basic structural and functional unit of all living tissues?** a) A) Cytoplasm b) B) Nucleus c) C) Cell d) Tissue