Cell Biology Introduction PDF

An introduction to Cell Biology Introduction It is the scientific discipline that studies cells-  Physiological properties  Structure  Organelles, interactions with their environment  Life cycle, division and death Cell  A cell is the smallest unit o...

An introduction to Cell Biology Introduction It is the scientific discipline that studies cells-  Physiological properties  Structure  Organelles, interactions with their environment  Life cycle, division and death Cell  A cell is the smallest unit of a living thing.  The cells are the basic building blocks of an organism  Cell- Tissues- Organs- Organ System  Every life is cellular History of cells 1665-Robert Hooke He looked at a thin slice of cork under his microscope. looked like a honeycomb like structure. Hooke called it as cells. He coined the term "Cell". Cellula- Small compartment. Micrographia - his famous work 1667- Anton van Leeuwenhoek First person to observe human cells and bacteria. named them as animalcules, meaning small animals. 1839-Schleiden & Theodor Schwann Proposed "Cell Theory" and described Cells as the functional and basic unit of life. 1858-Rudolf Virchow Formalized "Cell theory". He is known as the father of modern cell theory. 1924-Swedberg Centrifugation 1933 - Knoll & Ruska Discovered Electron Microscope Cell theory or Cell doctrine  The cell is the basic structural and functional unit of life.  All organisms are composed of cells.  All cells are produced by the division of preexisting cells.  Energy flow occurs within cells.  Cells contain hereditary information which is passed from cell to cell.  All cells have basically the same chemical composition. Two basic classes of cell 1. Prokaryotic cells 2. Eukaryotic cells They are distinguished by their size and the type of internal structures or organelles they contain. Classification of cell Eukaryotic cells  Cell that have unit membrane bound nuclei are called Eukaryotes.  Eu means true and karyon means nucleus.  It contains one or more paired, linear chromosomes composed of deoxyribonucleic acid (DNA) associated with histone proteins.  A nucleolus is present.  Membrane bound organelles are present. Prokaryotic Cells  The nuclear body is not bounded by a nuclear membrane.  It usually contains one circular chromosome composed of deoxyribonucleic acid (DNA) associated with histone-like proteins.  There is no nucleolus  The nuclear body is called a nucleoid  Internal membrane-bound organelles such as mitochondria, endoplasmic reticulum, Golgi apparatus, vacuoles, and lysosomes are absent.  No division of labor  Bacterial cells also contain flagellum, plasmid and capsule Difference between prokaryotic and Eukaryotic  Feature  Prokaryote  Eukaryote  Size  Small about 0.5  Up to 40 micrometers micrometers  Genetic  Circular DNA (in  DNA in form of linear  material  cytoplasm)  chromosomes ( in nucleus)    Many organelles:  Organelles  Few present, none  Double membranes e.g.:  membrane bound nucleus, mitochondria & chloroplasts  Single membrane e.g.: GA,  ER & lysosomes    Fungi: rigid, formed from  Cell walls  Rigid formed from  polysaccharide, chitin. glycoproteins (mainly  Plant: rigid, formed from murein) polysaccharides. E.g.: cellulose.  Animals no cell wall  Ribosome’s  70s  80s    