Cell Theory: A Comprehensive Guide (PDF)

Matthias Jacob Schleiden – is a German botanist whom said that the basic cell is the basic units of plants Theodore Schwann – is a German physician whom said that it was the basic unit of animal cells. Concluded both animal and plants are composed of cells Cells have independent l...

Matthias Jacob Schleiden – is a German botanist whom said that the basic cell is the basic units of plants Theodore Schwann – is a German physician whom said that it was the basic unit of animal cells. Concluded both animal and plants are composed of cells Cells have independent lives Robert Hooke – Coined the name cellula which means small rooms Rudolf Virchow – 1855 Omni cellula e cellula means that all cells arise from pre existing cells CELL THEORY 1. All organisms are made up of 1 or more cells 2. Cells is the smallest unit of life * Smallest cell = 0.0001 micrometer in bacteria * Largest cell = 170mm x 120, Ostrich egg 3. all cells arise by division of pre-existing cells 2 basic types of cells * Eukaryotic cell – Group of organisms that has nucleus. Animal cells and is surrounded by a nuclear membrane * Prokaryotic cell – has no nuclear membrane and does not have nucleus mainly bacteria, blue algae, and etc. 3 MAJOR COMPONENTS 1. Cell membrane – separates the cell from the external environment. It is made up of 2 layers of phospholipid layers. It also has many proteins embedded Functions Selective permeability Endocytosis - Phagocytosis – cell eating - Pinocytosis – cell drinking - Receptor – mediated endocytosis Exocytosis – removal of substances from cell  Compartmentalization Storage transport and secretion 2. Nucleus – control center and controls cellular activities by regulating RNA synthesis Composed of Chromatin – Major component composed of coiled strands of DNA which is bound to proteins called histones Euchromatin – loosely packer and it is light stained and is active genetic material Heterochromatin – Tightly packed and is dark stained and is unused genetic materials an example of heterochromatin is Barr body which is an inactivated x Chromosome in the nuclei of the female cells Nucleolus – Deep staining in the basophilic areas, is composed of granules and chromatin and it is the region where-in intensive ribosomal RNA synthesis undergoes Nucleoplasm – Semi fluid colloidal solution that chromatin and the materials and the nucleolus are suspended Nuclear Envelope / Nuclear membrane – is a double membrane, protein gate keeper, and it varies in size 3. Cytoplasm – gel like substance enclosed within the cell membrane. Composed of 70 – 90 percent water 3 groups of structure Organelles - Membrane bound - Major organelles are like mitochondria, ribosomes, golgi body and etc. - Little organs Cytoplasmic inclusions – structures that are more transient than organelles and less actively involved in cell metabolism - Includes secretory inclusions ( enzyme, acids, and proteins ) nutritive inclusions ( glycogen and lipids ) and pigment granules Cytoskeleton – keeps cell in shape  MEMBRANE BOUND ORGANELLES Endoplasmic reticulum - network of flattened sacs and branding tubules and is involved in protein synthesis, packaging, and processing of various cell substances Types of ER 1. Rough ER – Granular and has ribosomes. Function is protein synthesis 2. Smooth ER – no ribosomes attached and is involved in lipid synthesis and is a network of tubular membrane structures Mitochondria - site of chemical reaction that transfer energy form organic compounds to ATP - Power house of the cell - Largest cytoplasmic organelle Golgi apparatus / complex - Network of flattened membranous vesicles - Participates particularly in secretion - Polysaccharide synthesis Lysosome - Main site of intracellular digestion - Contains hydrolytic enzymes - Killing of pathogenic organisms, degradation of waste products Peroxisomes - Also called as the microbodies - Breaks down fatty acids - Breakdown of purines to urea - Breakdown of toxic compounds Secretary vesicles - Transport and delivery of their contents - Exocytosis and endocytosis NON MEBRANE BOUND ORGANELLES Ribosomes - Some free some attached - Made up of proteins and RNA  - Site of protein synthesis Cytoskeleton - Mesh of filamentous elements - Microtubules, microfilaments, and intermediate filaments - Keeps cell in shape - Composed of globular protein actin - Enables cell to change shape and move Microtubules - Makes up the cilia and the flagella - Long hollow tubules made up of tubuline proteins Intermediate Filaments – Fibrous proteins join to from rope like structures provide internal support Cilia and flagella - Assist I movement of the cell - Hair like organelles that extend to the surface of the cell - Cilia is short and many in number - Flagella Not numerous but long Junctions - Connecting points joining either cells or other cells Centrosomes - Contain the centrioles involved in mitosis