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Biology Cell Module

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    CHAPTER 2 : CELL STRUCTURE AND FUNCTIONS SUBTOPIC : 2.1 Prokaryotic and eukaryotic cells LEARNING OUTCOMES: a) State the three principles of cell theory.  b)   Explain the structures of prokaryotic and eukaryotic cells. c)   Illustrate and compare the structures of prokaryotic and eukaryotic cells (plant and animal cells). . COURSE FRAMEWORK EXPLANATION / ELABORATION NOTES Three principles of cell theory    All living things are composed of cells (All organisms are composed of one or more cells).    Cells are the structural and functional unit of life.    All cells come from pre-existing cells by division. Prokaryotic cells    Pro : before, early, primitive, first    Karyon : nucleus    Prokaryotic cell : Cell that has genetic material that is not enclosed by nuclear membrane.    e.g. of prokaryotic cell: bacteria Eukaryotic cells    Eu : true    Karyon : nucleus    Eukaryotic cell : Cell that has genetic material that is enclosed by nuclear membrane.    E.g. of eukaryotic cell : animal cell, plant cell Explanation about structures of eukaryotic cells    Have membrane-bounded nucleus     Nuclear envelope / membrane enclose the nucleus (separating its contents from the cytoplasm)    Genetic material is linear DNA that is associated with histone  protein    Has membrane-bounded organelles    There are two classes of organelles : 1)   Endomembrane system : organelles that communicate with one another via small vesicles or membrane channels 2)   Energy related organelles such as mitochondria, chloroplasts Comparison  between  prokaryotic and eukaryotic cells ***Refer to similarities and differences Similarities : -   Both cells are surrounded by plasma membrane -   Both cells have DNA as genetic material -   Both cells have cytoplasm, ribosome, smooth and rough ER, mitochondria, nucleus,  Nucleolus Cell Biology  Reference 1.   Cell and Molecular Biology 8  th  Edition , Gerald Karp 2.    Becker’s The World of Cell 8 th  edition 3.    Biology MC GrawHill 11 th  edition 4.    Biology The Dynamic Science 4 th  edition Russell   5.    Biological Science, 6  th  Edition , Freeman S., Quillin K., Allison 6.    Brooker - Biology 4th Edition 7.   Understanding Biology (Majors Biology), 2nd Edition    Differences  between prokaryotic and eukaryotic cells : Features / Prokaryotic cells Eukaryotic cells characteristics Cell division Binary fission with no spindle By mitosis or meiosis or both with spindle formation fiber formation Cell walls Composed of peptidoglycan Animal cell has no cell wall, plant cell has cellulose cell wall and cell wall of fungi composed of chitin Membrane-bounded Absent in prokaryotic cells Present in eukaryotic cells organelles Ribosome Has small size (70S) ribosome Has large size (80S) ribosome; Small size (70S) ribosome present in organelles Genetic materials Circular DNA lies freely in cytoplasm. Linear DNA located in double membrane- DNA not associate with histone protein. bounded nucleus. DNA associate with histone protein. Flagella Simple flagella lack of '9+2' Complex flagella with '9+2' microtubule microtubule arrangement arrangement Plasmid Present in some bacteria Absent in eukaryotic cell Cellular respiration Site of cellular respiration is mesosome Site of cellular respiration is mitochondrion  b) Explain the structures and functions of organelles Organelle :    Are structures that suspended within cytosol and perform specific functions inside cell.    Can be divided into membranous organelles and non- membranous organelles Membranous organelles Non-membranous organelles  Nucleus Ribosome Chloroplast Centriole Mitochondria Rough ER Smooth ER Golgi apparatus Lysosome Organelles Structures Functions     b) Explain the structures and functions of organelles Nucleus    Spherical or oval in shape    Double membrane nuclear envelope enclose the nucleus and separate it from cytoplasm.    Has outer membrane that is continuous with endoplasmic reticulum and also has inner membrane    Inner part of nucleus is nucleoplasm which is semifluid medium containing chromatin, nucleotides, mineral ions, enzymes and nucleolus    Surface of nuclear membrane has nuclear pore that regulate the entry and exit of molecules e.g.  protein, RNA from nucleus.     Nucleolus is small dense spherical body within nucleus that consist of RNA and  protein    Store genetic information / gene of a cell : contain chromatins / chromosomes in nucleoplasm    Control production of RNA and protein in cell    Control all activities of cell  by regulating synthesis of protein and enzymes Rough endoplasmic reticulum (ER)    Consist of network of membranous flattened sacs called cisternae    Membrane of ER separate the ER lumen @ cavity / cisternae space from the cytosol    Membrane of rough ER is continuous with the outer membrane of nucleus    There are ribosomes on outer surface of the rough ER membrane    Synthesis secretory proteins (e.g. hormone) -    polypeptides synthesized by ribosomes are transported to ER lumen -   inside ER lumen, the polypeptides are modified by enzymes (add carbohydrate chain to the protein forming glycoprotein)    Involve in intracellular transport of proteins (the glycoprotein is packaged inside transport vesicle and the vesicle is carried to Golgi body) Smooth ER    Consist of network of membranous tubules called cisternae    Membrane of ER separate the ER lumen @ cavity / cisternae space from the cytosol    Lack of ribosomes on outer surface of the smooth ER membrane    Site of lipid synthesis    Breakdown of stored glycogen to glucose in liver    Store calcium ions in sarcoplasmic reticulum of skeletal muscle    Detoxify drugs and poison in liver    Golgi apparatus  / body    Consist of a group of flattened membranous sacs called cisternae    Each cisterna has lumen    Has two sides : cis face and trans face    Cis face is usually located near the ER and receive transport vesicles from ER    Trans face bud off transport vesicles containing specific  products to be carried to other locations inside cell or to  plasma membrane for secretion    Modify, pack sorting of pro -   Cis face receive vesicles from ER -   Products of E modified during their transit from to trans face of Golgi -   Trans face pa modified  products in trans vesicles and sort the vesicle transported out of Golgi body    Form lysosome    Form polysaccharide e.g. pectin in G of plant cells w incorporated w into cell walls Lysosome    Spherical in shape    Single-membrane bounded organelle    Produced by Golgi apparatus    Contains hydrolytic enzymes    Involve in intracellular food digestion (phagocytosis)    Involve in autophagy (digestion of old @ worn out organelles)    Involve in autolysis (digestion of old @ damaged cells result in apoptosis Ribosome     Not bounded by membrane    Are complexes made of ribosomal RNA (rRNA) and  protein    Consist of two subunits : large subunit and small subunit    Can be found as free ribosomes (suspended in cytosol) and  bound ribosomes (attach to rough ER)    Site of protein synthesis -   most of the protein made by free ribosomes function within cytosol -    bound ribosomes make proteins that are inserted into membranes, for  packaging within organelle e.g. lysosome or secretory proteins Mitochondria    Rod-shaped    Double membrane- bounded organelle : -   smooth outer membrane -   highly folded inner membrane forming cristae    Cristae is highly folded to increase the surface area of inner membrane thus increasing the efficiency of energy / ATP  production    Intermembrane space is the narrow region between outer and inner membranes    Mitochondrial matrix containing enzymes, DNA and ribosomes is enclosed by the inner membrane    Site of cellular respiration / energy @ ATP production
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