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Cell Biology for Under-graduates - Dr HK Garg
- 1. An Overview ofCell Biology
- 2. What is aCell ? Cell is the smallest unit of a living organism which is responsible for all structural, biochemical and physio- logical functions of the organism. An Overview of Cell Biology
- 3. Early History ofCell An Overview of Cell Biology Year Scientist Contribution 1590 Z. Janssen F. Janssen Compound Microscope 1665 Robert Hooke Coined the term ‘Cell’ 1674 Anton Van Leeuwenhoek Studied Sperms, Blood Corpuscles & Protozoans 1839 Purkinje Named ‘Protoplasm’ 1831 Robert Brown Discovered ‘Nucleus’ 1839 Schleiden & Theodor Schwann Formulated Cell Theory Anton Van Leeuwenhoek
- 4. Techniques used tostudy a Cell Microscopy : Principle A beam of light or electrons is passed on the object. The beam, reflected by the object, forms an image on eyes, photographic plate or television screen. An Overview of Cell Biology
- 5. Techniques used tostudy a Cell Microscopy : Resolution The power to separate any two closely situated points after magnifying them, is called resolution power. Resolution (d) depends upon wavelength (λ) of light and numerical aperture (NA) of the objective lens. Therefore, d = λ / 2NA An Overview of Cell Biology
- 6. Techniques used tostudy a Cell Microscopy : Magnifying Power The power of a microscope to enlarge the image of an object as much as possible is called its magnifying power. The magnifying power (X) of light microscope = power of its objective lens X power of its ocular lens. An Overview of Cell Biology
- 7. Techniques used tostudy a Cell Microscopy : Compound Microscope Electron Microscope An Overview of Cell Biology Image formation by a Light Microscope
- 8. Electron Microscopy An Overviewof Cell Biology Transmission Electron Microscope Scanning Electron Microscope
- 9. Cell Theory An Overviewof Cell Biology The body of all living organisms is made up of one or more cells. All vital activities of an organism are performed by cells. New cells are formed by the division of pre-existing cells. Cells carry hereditary units.
- 10. Types of Cell Prokaryotic(pro: primitive or before, karyon : nucleus) example : PPLO (Pleuro pneumonia like organism), Bacterium, Blue-green algae. Eukaryotic (eu : good, karyon : nucleus) example : all plants, animals and micro-organisms. An Overview of Cell Biology
- 11. Prokaryotic Cell An Overviewof Cell Biology • Nucleus incipient or absent. • No nucleolus and nuclear envelop. • Nuclear material not arranged in the form of chromatin, rather scattered in the cytoplasm. • Membranous structure missing.
- 12. Eukaryotic Cell • Eukaryoticcells are more complex than Prokaryotic ones. • Nucleus enveloped by a distinct sheath - nuclear membrane. • Nucleolus present. • Cytoplasmic membrane organelles like Endoplasmic reticulum, Golgi bodies, Lysosomes, Mitochondria, etc. are also found. An Overview of Cell Biology
- 13. Comparison between thetwo : Prokaryotic Cell and Eukaryotic Cell An Overview of Cell Biology Structures Prokaryotic Cells Eukaryotic Cells 1. Cell wall Present Present in plant cells; absent in animal cells 2. Plasma membrane Present Present 3. Endoplasmic reticulum Absent Present 4. Golgi bodies Absent Present 5. Mitochondria Absent Present 6. Lysosomes Absent Present
- 14. Comparison between thetwo : Prokaryotic Cell and Eukaryotic Cell An Overview of Cell Biology Structures Prokaryotic Cells Eukaryotic Cells 7. Ribosomes Present - 70S Present - 80S 8. Cytoskeleton Absent Present 9. Centriole Absent Present (absent in higher plants) 10. Cilia & Flagella Simple structure of protein - flagellin Complex 9+2 structure of tubulin 11. Vesicles Present Present 12. Vacuoles Absent Present
- 15. Comparison between thetwo : a Prokaryotic Cell and a Eukaryotic Cell An Overview of Cell Biology Structures Prokaryotic Cells Eukaryotic Cells 13. Nucleus Absent Present 14. Nuclear membrane Absent Present 15. Nucleolus with mitotic apparatus Absent Present 16. Genetic material Circular or linear; Double stranded DNA; genes are not interrupted by introns Linear double stranded DNA; genes frequently interrupted by introns sequences 17. Chromatin with histone Present Absent
- 16. Animal Cell An Overviewof Cell Biology
- 17. Plant Cell An Overviewof Cell Biology
- 18. Functions of DifferentCell Organelles An Overview of Cell Biology Organelles Functions 1. Plasma membrane • To maintain the external shape of the cell. • To protect the protoplasm & its constituents. • To control the entry and exit of the material across the membrane. 2. Endoplasmic reticulum • To exchange materials between external environment and cell organelles. • ER tubules provide additional surface for metabolic activities • To synthesize steroid material. 3. Mitochondria • To produce energy by the oxidation of food material. • To provide energy for vital activities thus acts as power house of the cell.
- 19. Functions of DifferentCell Organelles An Overview of Cell Biology Organelles Functions 4. Golgi bodies • To collect enzymes & proteins. • To finish, package & dispatch a variety of compounds. • To form acrosome in sperms. 5. Ribosomes • To synthesize protein. 6. Lysosomes • To store enzymes for digestion of various fragments of cell, their proteins and carbohydrates. • To engulf bacteria and other toxic products entering into the cell.
- 20. Functions of DifferentCell Organelles An Overview of Cell Biology Organelles Functions 7. Nuclear membrane • To maintain shape of the nucleus. • To regulate the entry & exit of the material in the nucleus. 8. Nucleolus • To store RNA and to synthesize protein by it. 9. Nuclear material or chromatic network • To carry hereditary characters and pass them from one generation to another. • To regulate all vital activities of the cell.
- 21. Cell Reproduction Amitosis An Overviewof Cell Biology Amitosis
- 22. Cell Reproduction Mitosis • Interphase: G1, S, G2 • Prophase • Metaphase • Anaphase • Telophase • Cytokinesis An Overview of Cell Biology
- 23. Cell Reproduction Meiosis • FirstMeiotic or Heterotypic • Prophase - Leptotene Zygotene Pachytene Diplotene Diakinesis • Metaphase • Anaphase • Telophase • Cytokinesis An Overview of Cell Biology
- 24. Cell Reproduction Meiosis • SecondMeiotic or Homotypic • Prophase • Metaphase • Anaphase • Telophase • Cytokinesis An Overview of Cell Biology
- 25. Significance of Meiosis •Four haploid cells are formed • During fertilization, one male and one female gamete fuses to form a diploid zygote. This is how the chromosome number of a species remains the same generation after generation. • During the first meiotic division, crossing over between the homologous chromosomes allow chromatid exchange by which new hereditary combinations are developed. An Overview of Cell Biology
- 26. Cell Death Necrosis Apoptosis During thedevelopment of multicellular eukaryotic organisms (embryo-genesis, metamorphosis and tissue turn over), unwanted cells are eliminated through the process of programmed cell-death or apoptosis. An Overview of Cell Biology
- 27. Cell Death Apoptosis involvesthe activation of a pathway that leads to suicide of the cell by characteristic process in which • the cell becomes more compact; • blebbing occurs at the membranes; • the chromatin becomes condensed; and • the DNA is fragmented. Ultimately, the dead cell become fragmented into membrane bound pieces and are engulfed by surrounding cells. An Overview of Cell Biology
- 28. Cell Death Apoptosis isimportant in • tissue development; • immune defense; and • In the detection of cancerous cells; An Overview of Cell Biology
- 29. Course Content Unit -1 •History of Cell Biology • Cell Theory, Prokaryotic & Eukaryotic Cells • Microscopy : Principle & Applications, Electron Microscopy • Structure & Transport across the plasma membrane • Extra Nuclear Organization of Cell An Overview of Cell Biology
- 30. Course Content Unit -2 • Nuclear Organization of Cell • Nucleo-cytoplasmic Interactions • Cell Division : Amitosis, Mitosis & Meiosis • Cell Death : Necrosis & Apoptosis An Overview of Cell Biology