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154 lecture 1 cell
 

154 lecture 1 cell

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histology 154 cell

histology 154 cell
lecture 1
dr mathew

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    154 lecture 1 cell 154 lecture 1 cell Presentation Transcript

    • CELLCELL STRUCTURESTRUCTURE AND FUNCTIONAND FUNCTION
    • CellCell
    • PLASMA MEMBRANEPLASMA MEMBRANE
    • PLASMA MEMBRANEPLASMA MEMBRANE It is necessary that for the proper functioning the cells and cell components should be separated from the outside environment.
    • PLASMA MEMBRANEPLASMA MEMBRANE A lipid/protein/carbohydrate complex. Provides a barrier to the cell Forms a boundary between the cell and its environment Contains transport and signaling systems Membranes bound organelles Segregation of biochemical activities within the cell
    • PLASMA MEMBRANEPLASMA MEMBRANE The lipids have hydrophilic polar heads pointing out and the hydrophobic portion forming the core.
    • PLASMA MEMBRANEPLASMA MEMBRANE Lipid bilayers are fluid. Individual phospholipids diffuse rapidly throughout the two dimensional surface of the membrane. The Fluid Mosaic Model This is known as the fluid mosaic model of biological membranes (mosaic because it includes molecules other than phospholipids, such as proteins, cholesterol, and other types of molecules).
    • PLASMA MEMBRANEPLASMA MEMBRANE
    • PLASMA MEMBRANEPLASMA MEMBRANE APPEARS TRILAMINAR UNDER THE TRANSMISSION ELECTRON MICROSCOPE TWO DENSE LINES (2.5 – 3.0 nm) A LESS DENSE INTERMEDIATE ZONE
    • PLASMA MEMBRANEPLASMA MEMBRANE
    • GLYCOCALYXGLYCOCALYX THE CARBOHYDRATE MOLECULES FORM A THIN OUTER LAYER CALLED THE GLYCOCALYX
    • PLASMA MEMBRANEPLASMA MEMBRANE Functions 1. Semi-permeable barrier 2. Regulate transport in and out of cell. 3. Communication 4. Adhesion
    • PLASMA MEMBRANEPLASMA MEMBRANE Functions 5. Barrier Functions: The lipid bilayer accounts for the basic barrier functions of the plasma membrane. Permeable to water, O2 and small hydrophobic molecules such as steroids, ethanol Impermeable to highly charged molecules and charged ions. 6. Transport in and out of the plasma membrane
    • NUCLEUSNUCLEUS
    • NUCLEUSNUCLEUS The nucleus is the controlling station ofThe nucleus is the controlling station of eukaryotic cell.eukaryotic cell. Usually the nucleus is round and is theUsually the nucleus is round and is the largest organelle in the cell.largest organelle in the cell.
    • NUCLEUSNUCLEUS It is surrounded by a membrane, calledIt is surrounded by a membrane, called the nuclear envelope, which is similar tothe nuclear envelope, which is similar to the cell membrane that encloses thethe cell membrane that encloses the entire cell.entire cell.
    • NUCLEUSNUCLEUS Nuclear membrane possess specificNuclear membrane possess specific openings called nuclear pores, that allowopenings called nuclear pores, that allow specific materials to pass in and out ofspecific materials to pass in and out of the nucleus.the nucleus.
    • NUCLEUSNUCLEUS Attached to the nuclear envelope is theAttached to the nuclear envelope is the endoplasmic reticulum.endoplasmic reticulum. The nucleus is surrounded by theThe nucleus is surrounded by the cytoplasm inside a cell.cytoplasm inside a cell.
    • NUCLEUSNUCLEUS Structurally, the nucleus isStructurally, the nucleus is composed of three main parts,composed of three main parts, the nucleolus,the nucleolus, the nuclear envelope, andthe nuclear envelope, and the chromatin.the chromatin.
    • The nuclear pore and envelope Insures that the interior of the nucleus is isolated from a cell's cytoplasm, allowing two different environments to be maintained. The membrane has two layers that enclose a distinct space in between and marked by large pores.
    • The nuclear pore and envelope The membrane is very selective, permitting only certain substances to enter or leave the nucleus. In addition, the space contained within the double-layered nuclear membrane is continuous at points with the endoplasmic reticulum.
    • The nuclear pore and envelope
    • TRANSMISSIONTRANSMISSION ELECTRONELECTRON MICROGRAPHMICROGRAPH OFOF NUCLEAR PORENUCLEAR PORE
    • NUCLEOLUSNUCLEOLUS Principal RNA containing structure of the nucleus. It is rich in protein is surrounded by a ring of heterochromatin which may penetrate into the main body of the nucleolar complex.
    • NUCLEOLUSNUCLEOLUS The fine structure of the nucleolus reveals the presence of a fibrillar and a granular area, each composed of ribonucleoproeins, and each is related to the biogenesis of ribosomes.
    • CHROMATINCHROMATIN Chromatin is the name that describes nuclear material that contains the genetic code. The chromatin (meaning "colored substance") contains DNA and proteins. Chromatin gives rise to chromosomes.
    • CHROMATINCHROMATIN Two types of chromatin material Heterochromatin and Euchromatin.
    • HETEROCHROMATINHETEROCHROMATIN  The darkly stained, condensed region of the chromatin is known as heterochromatin.  The heterochromatin occurs around the nucleolus and at the periphery.  It is supposed to be metabolically and genetically inert because it contains comparatively small amount of DNA and large amount of RNA.
    • EUCHROMATINEUCHROMATIN The light stained and diffused region of the chromatin is called euchromatin. The euchromatin contains compatatively large amount of DNA.
    • Nuclear poreNuclear pore Nuclear envelopeNuclear envelope EuchromatinEuchromatin HeterochromatinHeterochromatin NUCLEOLUSNUCLEOLUS Pars granulosaPars granulosa Pars fibrosaPars fibrosa NucleolusNucleolus organizing centreorganizing centre Rough endoplasmicRough endoplasmic reticulumreticulum
    • GOLGI APPARATUSGOLGI APPARATUS
    • GOLGI COMPLEXGOLGI COMPLEX Golgi complex is a disc shaped structure with central flattened, plate like compartments or cisternae, peripheral network of interconnecting tubules and peripherally occuring vesicles.
    • FUNCTIONS OF GOLGIFUNCTIONS OF GOLGI COMPLEXCOMPLEX Golgi complex is concerned with the formation and packaging of materials for export from the cell
    • ENDOPLASMICENDOPLASMIC RETICULUMRETICULUM
    • GRANULAR OR ROUGHGRANULAR OR ROUGH ENDOPLASMIC RETICULUMENDOPLASMIC RETICULUM
    • GRANULAR OR ROUGHGRANULAR OR ROUGH ENDOPLASMIC RETICULUMENDOPLASMIC RETICULUM It possesses rough walls because the ribosomes remain attached with its membranes. The granular or rough type of endoplasmic reticulum is found abundantly in those cells which are active in protein synthesis.
    • FUNCTIONS OF GRANULAR OR ROUGHFUNCTIONS OF GRANULAR OR ROUGH ENDOPLASMIC RETICULUMENDOPLASMIC RETICULUM Rough ER is involved in protein synthesis. The endoplasmic reticulum also functions as a transport system. Protein molecules move from the rough ER into the smooth ER, which then sends them enclosed within the vesicles usually to the Golgi complex.
    • AGRANULAR OR SMOOTHAGRANULAR OR SMOOTH ENDOPLASMIC RETICULUMENDOPLASMIC RETICULUM
    • FUNCTIONS OF AGRANULAR ORFUNCTIONS OF AGRANULAR OR SMOOTHSMOOTH ENDOPLASMIC RETICULUMENDOPLASMIC RETICULUM The smooth type of endoplasmic reticulum occurs mostly in those cells, which have no active participation in the synthesis of proteins. It is involved in the synthesis of LIPIDS, GLYCOGEN AND STEROIDS
    • RIBOSOMESRIBOSOMES The ribosomes are small, dense, rounded and granular particles of ribonucleoprotein. They are found either freely in the matrix of mitochondria, chloroplast and cytoplasm or found attached on the surface of the endoplasmic reticulum and nucleus.
    • RIBOSOMESRIBOSOMES Ribosomes are present in most prokaryotic and eukaryotic cells. They are the sites of protein synthesis where amino acids are assembled to produce the polypeptide chain.
    • RIBOSOMESRIBOSOMES Ribosomes are classified into two types, based on the size and the sedimentation coefficient (S). They are: 1. 70S Ribosomes and 2. 80S Ribosomes
    • LYSOSOMESLYSOSOMES
    • The lysosomes are tiny, membrane bounded, vesicular structures of the cytoplasm which perform intracellular digestion of the cell. The term lysosome means digestive body (Gr., lyso-digestive, soma-body). LYSOSOMESLYSOSOMES
    • SUICIDE BAGS OF THE CELL FUNCTIONS OFFUNCTIONS OF LYSOSOMESLYSOSOMES
    • Cytoplasm of some eukaryotic cells contains two cylindrical, rod-shaped, microtubular structures, called centrioles, near the nucleus. CENTRIOLESCENTRIOLES
    • Centrioles lack limiting membrane and DNA or RNA. It gives rise to the mitotic apparatus during mitosis or meiosis. CENTRIOLESCENTRIOLES
    • In flagellated or ciliated cells centrioles are found arranged just beneath the plasma membrane to form and bear flagella or cilia. When a centriole bears a flagellum or cilium, it is called basal body. BASAL BODIESBASAL BODIES
    • Peroxisomes are organelles that resemble lysosomes. They are present in many animal and plant cells. They contain oxidative enzymes. PEROXISOMESPEROXISOMES
    • Peroxisomes are distinguished by a crystalline structure inside a sac which also contains amorphous gray material. They are self replicating, like the mitochondria. They also enlarge and bud to produce new peroxisomes. PEROXISOMESPEROXISOMES
    • Peroxisomes protect the cells from the action of toxic substances like hydrogen peroxide, or other metabolites. PEROXISOMESPEROXISOMES
    • Morphologically they resemble peroxisomes, but the crystalloid core consists of dense rods. GLYOXISOMESGLYOXISOMES
    • They have enzymes for fatty acid metabolism and gluconeogenesis. Glyoxisomes are present in yeast and the oil rich seeds of many plants. GLYOXISOMESGLYOXISOMES
    • MITOCHONDRIAMITOCHONDRIA
    • MITOCHONDRIA  Mitochondria contain two membranes, separated by a space.  Both are the typical "unit membrane" in structure. Inside the space enclosed by the inner membrane is the matrix.
    • MITOCHONDRIA  The mitochondrial matrix contains lipids, proteins, circular DNA molecules, 70S ribosomes and certain granules which are related to the ability of mitochondria to accumulate ions.
    • MITOCHONDRIAL CRESTS OR CRISTAE The inner mitochondrial membrane increases its surface area by giving out plate-like or tubular invaginations called MITOCHONDRIAL CRESTS OR CRISTAE
    • MITOCHONDRIAL CRESTS OR CRISTAE  Mitochondria replicate much like bacterial cells.  They undergo fission. This involves a furrowing of the inner and then the outer membrane of the mitochondrion.  Then the two daughter mitochondria split.  Before the mitochondrion divides, the mitochondrial DNA replication occurs.  Sometimes new mitochondria are synthesized.
    • "POWER HOUSES" OF THE CELL.
    • CYTOSKELETON  MICROFILAMENTS: Stabilize cell shape Cell motility  MICROTUBULES: Serve as tracks along which materials are moved in the cell
    • CELL DIVISION MITOSIS AND MEIOSIS
    • CELL DIVISION  MITOSIS VS MEIOSIS  purpose produces somatic cells produces reproductive cells (body, growth)  process cell duplication reduction division (diploid -> diploid) (diploid -> haploid)  number of 1 cell division 2 cell divisions divisions  product 1 -> 2 daughter cells 1 -> 4 cells (gametes) daughter cells identical daughter cells different (to each other & mother cell)
    • CELL CYCLE  DIFFERENT PHASES OF CELL CYCLE  DNA synthesis occurs only during one phase of the cell cycle called the S (synthetic) phase.  A gap of time occurs between the synthetic phase and the cell division (Mitosis)  and another gap occurs after division and the next S phase.  Thus the cell cycle in eukaryotes may be divided into the mitotic phase (M phase), G1 phase (the first gap) the S phase and the G2 phase (the second gap).  Many cell types which are said to be in the resting stage, suspend cell cycle after mitosis and just prior to the S phase, such cells are said to be in the G0 state.
    • MICROSCOPYMICROSCOPY
    • CellCell
    • IMMUNO HISTO CHEMISTRY
    • CELL CULTURE
    • CELL DIVISION- MITOSIS  A. Interphase.  1. This phase includes gap 1, S and gap 2 periods of cell cycle.  2. Since the replication of DNA occurs in the S phase, the nucleus has twice the diploid amount of DNA.  3. As the cell prepares to divide, the chromosome condense and become visible.
    • CELL DIVISION- MITOSIS  B. Prophase.  1. Chromosomes become visible, Each chromosome consists of a pair of long parallel strands (sister chromatids), which are held together at the centromere.  2. Crossing over between the sister chromatids may occur at this stage.  3. The nuclear membrane and the nucleolus disappears.  4. The centrioles divide and the daughter centrioles migrate towards the opposite poles of the cell.
    • CELL DIVISION- MITOSIS  C. Metaphase  1. In this stage the chromosomes have reached the maximum level of contraction.  2. The spindle fibers form and chromosomes move to the equatorial plate of the cell.
    • CELL DIVISION- MITOSIS  D. Anaphase  1. In anaphase the centromere divides and the paired chromatids separate.  2. The spindle fibre contracts, bringing the daughter chromosomes to the two poles of the cell.
    • CELL DIVISION- MITOSIS  E. Telophase  1. As the daughter chromosomes reach the cell, the cytoplasm divides, and the cell plate forms.  2. The chromosomes start to unwind.  3. The nuclear membrane reforms.
    • SAMPLE PREPARATIONSAMPLE PREPARATION FOR LIGHTFOR LIGHT MICROSCOPYMICROSCOPY
    • SAMPLE PREPARATION: i) Fixation: stabilizes cellular constituents (proteins and polymeric nucleic acids) ii) dehydrate/embed: infiltrate tissue with solid material to allow for cutting -dehydrate in ethanol/xylene (removes lipids) -infiltrate with paraffin or plastic -can freeze to solidify tissue for sectioning (cryosectioning)
    • iii) Microtomy: cut tissue very thin -typically 1 - 10 micrometers thick -paraffin/plastic embedded tissue sectioned with micro tome -frozen samples sectioned with cryostat (microtome within a freezer)
    • iv) stain specimen with dyes (classical histology): paraffin is removed from section then section is re- hydrated and stained Routine stain -hematoxylin: basic dye –STAINS NUCLEUS -eosin: acid dye STAINS CYTOPLASM
    • THANK YOUTHANK YOU