Prokaryotic cell First cell type on earth Cell type of Bacteria and Archaea No membrane bound nucleus Nucleoid = region of DNA concentration
Eukaryotic cell Organelles not bound by membranes Nucleus bound by membrane Fungi, Protists, Plant, and Animal cells Possess many organellesAnimal cellPlant cell
Structure of cell Each cell is formed by cell body andmembrane Cell membrane –Separate cell body fromthe surrounding cell Cell body -CytoplasmNucleus
Cell membrane Protective sheath enveloping the cell body Separate intracellular and extracellular fluid Permits exchange of some substance Thickness- 75A to111A Double layer ofPhospholipids & Proteins
lipid layer Cell membrane-Bilayered component Lipids are cholesterols and phospholipids Phospholipids = Phosphrous and fatty acid(Amino Phospholipid, Phosphetidyle GlycerolPhosphetidyle Inositol)Outer part- Hydrophilic(soluble in water)Inner part- Hydrophobic(soluble in fat)
Significance of lipid layer Forms semi-permeable membrane Fat soluble substance can pass through it.-O2, CO2 and alcohols Barrier to water soluble materials-Glucose, Urea, Electrolytes
Protein layer Glycoprotein Two type Integral protein and peripheral protein
Significance of protein layer Integral proteins- Structural IntegrityChannels(formed by integral protein)Diffusion of water soluble substanceGlucose, Electrolytes Receptors proteinReceptor for hormones andneurotransmitterRecognize certain chemicals Carrier protein-Transport of substance(active or passive) Act as antigen-act as antigen and provide antibodyformation
Carbohydrate Attached to protein or lipid Significance- Negatively charged-Glucocalyx of neighboring cellhelp in tight fixation.-Receptor for some hormone-Contain specific antigen(RBC-blood groupantigen)
Cytoplasm Viscous fluid containing organelles Interconnected filaments & fibers Organelles Fluid= Cytosol Various particles(Different shape and size)-Proteins, Carbohydrate,lipids and Electrolytes. 200mg/ml of protein High K + low Ca+2 low Na+
Cytoskeleton Filaments & Fibers Made of 3 fiber types◦ Microfilaments◦ Microtubules◦ Intermediate filaments 3 functions:◦ Mechanical support◦ Anchor organelles◦ Help move substancesTransportShape of cellActin and myosinShape of cell
A = actin, IF = intermediate filament, MT = microtubule
Organelle in Cytoplasm Organelle caries out various functions Two type- Bound by limiting membraneEndoplasmic reticulumGolgi apparatuslysome, PeroxisomeMitochondria Not bounded by limiting membraneChromosome, RibosomeMicrofilaments, Microtubules
Endoplasmic Reticulum Network of tubular and micrsomalvesicular structure Outer side-Limiting Membrane Inner side- Endoplasmic Matrix(lumen) Helps to move substances within cellsTwo types◦ Rough endoplasmic reticulum◦ Smooth endoplasmic reticulum
Rough endoplasmic reticulum Ribosomes are attached to surface◦ Manufacture proteins◦ Not all ribosomes attached to rough ER May modify proteins from ribosome Protein pass through membrane andaccumulate in cisternae.
Smooth EndoplasmicReticulum No attached ribosomes Various enzymes are present on outersurface Enzymes- Metabolic process of cell
Smooth endoplasmic reticulum with associated vesiclesBy courtesy of Rose Watson, Cancer Research UK.
Significance of Smooth EndoplasmicReticulum Carbohydrate metabolism Synthesis of non protein substance◦ Cholesterol◦ Steroid hormones◦ Sebum Catabolism of toxic substance Cooperate with rough endoplasmic reticulumand Golgi apparatus to synthesize new cellmembrane. Specialized typeIn skeletal muscle-sarcoplasmic reticulum
Golgi Apparatus or GolgiBody Present in all cell except Red Blood Cell Situated near nucleus Consist of 5 to 8 membranous sac The Sacs are flattened and called asCisternae
Function of Golgi Body Processing and delivering the proteinmolecule to different parts of the cell.Protein synthesized from endoplasmic reticulumTransported in the form of Reticular VesicleTo Golgi Body where it is processed and sorted outPacked in the form of Secretory Granules, SecretoryVesiclesVesicles delivered by golgi body leave the cellby exocytosis.lysosomal Vesicles
Lysosomes Vesicular organelle 80 to 800nm in diameter Have thickest covering membrane Many small granules present in lysosomes Contain digestive enzymes(hydrolyticenzyme) More than 40 different type of hydroxylases All enzyme- lysozymes
Functions◦ Digests protein, carbohydrate, Lipid,nucleic acids◦ Destruction of bacteria and other foreignbody.◦ Removal of unwanted cell in embryo◦ Break down old cell parts◦ When bacteria enter into the celllysosomes rupture and immediately digestthe invaded bacteria or foreign body.
Lysosomal storage disease Enzymes are defective because of gene Materials that they normally degrade willaccumulate within late endosomes and lysosomes.e.g. Tay-Sachs disease Hurlers Syndrome: Failure to metabolize certainmucopolysaccharides causes the accumulation oflarge amounts of matrix within connectivetissue, which distorts the growth of many parts ofthe body.
Peroxisome Membrane limited vesicle Derived from endoplasmic reticulum Contain oxidative enzymes (Urate oxidase and D- aminoacidoxidase)
Function of peroxisome Hydrogen peroxide is produced bypoisons or alcohol(ethanol and formaldehyde) Peroxisome ruptures when hydrogenperoxide is formed in cell. Oxidases destroys hydrogen peroxide Also destroy other enzymes necessaryfor its production Gluconeogenesis from fats anddegradation of purine and fat.
Zellweger syndromeGenetic abnormality in peroxisomebiogenesis
Mitochondria Rod shaped, oval shaped structure Diameter - 0.5 to 1 μm Bilayered membranous organelleOuter layer- SmoothInner layer- Series of shelf like projection-Cristae(provide large surface area) Contain RNA and DNA
Principle source of chemical energy inmost of the cells Enzymes are located in mitochondrialmatrix and inner mitochondrial matrix.
Function Break down fuel molecules (cellularrespiration)GlucoseFatty acids Production of energy by catabolism ofdigested food particles Stored in the form of ATP molecules So It is power house of cell Energy released by breakdown of ATPmoleculeWhen needed Mitochondria contain enzymes for citric acid
Mitochondria are distributed within a cellaccording to regional energyrequirements-Near the base of cilia-Near basal domain of cells of proximalconvulated tubules-Proximal end of flagellum Genetic diseases of mitochondria affectperticular tissuesEx. Mitochondrial myopathiesMitochondrial neuropathies
Ribosomes It is granular structure Diameter of 15 to 20 nm Contain 65%RNA and 35% Protein Some ribosomes remain free incytoplasmFunction of free ribosome Synthesis of protein from amino acid Synthesis of protein part ofhemoglobin Protein molecules of peroxisome
Nucleus Control center of cell 3 to 10 μm in diameter Double membrane(Nuclear membrane) Contains◦ Nucleoplasm◦ Nucleolus
Nuclear membrane Double layered, porous in nature Communicate with cytoplasm Outer layer continuous as endoplasmicreticulum Inner space forms lumen of endoplasmicreticulum Pores- Guarded by protein- Diameter 80nm to 100nm
Nucleoplasm Gel like substance Contain DNA Called aschromatin One or more in each nucleus Contain RNA and some proteins RNA synthesized by 5 pairs ofchromosome Condensed to form subunit of ribosome Subunit travel to cytoplasm through pore Fusion of subunits lead to formation ofRibosomeNucleoli
Function of Nucleus Control center for all activity of cell It sends genetic information in the formof DNA to cytoplasm for synthesis ofspecific enzymes Enzymes are responsible for variousmetabolic reactions. Genes present in the nucleus controlscell division. The hereditary information is stored inthe nucleus and transferred fromone generation to next.
General adhesive contactCalcium dependent adhesion moleculeCadherinsselectinsIntegrinsCalcium independent adhesionmoleculeMost are transmembrane proteinsN-CAMsI-CAMs
Specialized Adhesive ContactsOccluding Junction( Tight junction )-Tight junction is made up of ridges-Ridges have two halves which are inclose contact- provide strength and stability-prevent movement of ions and proteinDesmosomesHemidesmosomes
Communicating junction(gap junction) Cytoplasm of two cells is connected bychannels Diameter of channel 3 nm Passage of Ions, Glucose, Amino acid Rapid propagation of action potentialConnexon
Molecule Movement & Cells Passive Transport Active Transport Endocytosis(phagocytosis & pinocytosis) Exocytosis
Passive Transport No energy required Move due to gradient◦ differences inconcentration, pressure, charge Move to equalize gradient◦ High concentration moves toward lowconcentration.
Types of Passive Transport1. Diffusion2. Osmosis3. Facilitated diffusion
Diffusion Molecules move toequalize concentrationOsmosis Special form of diffusion Fluid flows from lower soluteconcentration Often involves movement of water◦ Into cell◦ Out of cell
Solution Differences & CellsSolvent + Solute = Solution Hypotonic◦ Solutes in cell more than outside◦ Outside solvent will flow into cell Isotonic◦ Solutes equal inside & out of cell Hypertonic◦ Solutes greater outside cell◦ Fluid will flow out of cell
Facilitated Diffusion Differentially permeable membrane Channels (are specific) help moleculeor ions enter or leave the cell Channels usually are transportproteins(aquaporins facilitate the movement ofwater) No energy is used
Process of Facilitated Transport Protein binds with molecule Shape of protein changes Molecule moves across membrane
Active Transport Molecular movement Requires energy (against gradient) Example is sodium-potassium pump
Endocytosis Movement of large material◦ Particles◦ Organisms◦ Large molecules Movement is into the cellsTypes of Endocytosis◦ Bulk-phase (nonspecific)◦ Receptor-mediated (specific)
Process of Endocytosis Plasma membrane surrounds material Edges of membrane meet together Membranes fuse to form vesicle
Exocytosis Reverse of endocytosis Cell discharges material
References Grey’s textbook of human anatomy40th edition Guyton and Hall textbook of medicalphysiology 12th edition Ganong’s textbook of medical physiology 21stedition Human physiology volume-1,Dr. C.CChatterjee Text book of human histology, Inderbir singh http://www.biologymad.com/resources http://biology.about.com/od/molecularbiology http://rarediseases.about.com/od/rarediseasesz/a/030505.htm