Parts of a Cell


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This describes the parts and functions of a cell.

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Parts of a Cell

  1. 1. Three Major Parts of the Cell:1. Plasma Membrane2. Cytoplasm3. Nucleus
  2. 2. • Siomai-like• Structure: Double layer of phospholipid molecules • Proteins are embedded in it. • Two Kinds of Protein: Integral and Peripheral Proteins • Phosphate Head: Polar and Hydrophilic • Lipid Tail: Nonpolar and Hydrophobic
  3. 3.  Structure: Fluid mosaic model  “Fluid” – configuration of the phospholipid molecules  “Mosaic” – presence of proteins Lipid and other molecules move about in themembrane. The plasma membrane is not smooth.
  4. 4.  Functions:1. Selectively permeable2. Protects the cell3. Separates the cell from its environment4. Gives shape to the cell “Plasma” – living Paramecium – pellicle
  5. 5.  First structural part to be observed Structure: Spherical in shape and located at the center of the cell It has three parts: 1. Nucleoplasm 2. Nucleolus 3. Nuclear Envelope / Nuclear Membrane
  6. 6. 1. Nucleoplasm - protein-rich protoplasm where nucleolus and chromatinsare suspended - Chromatins become chromosomes when the cell is dividing.2. Nucleolus - Darker area, for synthesis and storage of RNA3. Nuclear Membrane / Nuclear Envelope - Double membrane separating the nucleus from cytoplasm - Prokaryotic Cell and Eukaryotic Cell - Not a solid barrier (has nuclear pores)
  7. 7.  Prokaryotes - cells with no distinct nucleus Ex. Bacteria Eukaryotes - cells with distinct nucleus Ex. Animal Cell
  8. 8. • Control Center of the Cell• Contains most of the cell’s genetic material (DNA)
  9. 9.  Two Types:1. Cytoplasm – protoplasm lying around the nucleus2. Karyoplasm / Nucleoplasm – protoplasm lying inside the nucleus* The structure enclosed within the cell membrane and outside the nucleus is the cytoplasm.
  10. 10. • Material between the cell membrane and the nucleus• Appears: 1. Clear 2. Viscous 3. ColloidalFound in are different structures: 1. Endomembrane System 2. Organelles 3. Supramolecular Complex
  11. 11. Endoplasmic Reticulum (ER) Structure: Network of membranes; tiny canals formed by two parallel membranes Two distinct regions: 1. Rough ER 2. Smooth ER
  12. 12. 1. Rough ER Appears rough because of the presence of ribosomes Many types of specialized cells secrete proteins produced by the RER (Ex: White Blood Cell in a human). Proteins destined for secretion are synthesized by ribosomes attached to RER (Ex: Glycoproteins).
  13. 13. 2. Smooth ER Its enzymes synthesize fats, phospholipids, steroids, and other lipids. Carbohydrate Metabolism – done by SER in the liver Its enzymes detoxify drugs and other poisons.
  14. 14. Serves as a channel for products produced in the cell
  15. 15. Golgi Apparatus• Discovered by Camilo Golgi (nerve cell of an owl)• Flattened membranous sac
  16. 16. Functions: • Works together with the ER. • Serves as the Package Counter of the CellAfter processing and packaging of substances in the golgi apparatus, a clean up is needed. Cleaning is done by the lysosome.
  17. 17. - Various structures like miniature organs that perform specific functions
  18. 18. 1. Lysosomes Not commonly found in plant cells Membrane-bound organelles Contain hydrolytic enzymes These enzymes hydrolyze the cell when the lysosomial membrane is damaged.  What does hydrolytic enzyme do? 1. Breakdown of macromolecules (proteins, lipids, carbohydrates) 2. Destroys bacteria and other microorganisms 3. Destroys old cells (Programmed cell destruction)  “Suicide Bag of Cell”
  19. 19. Organelles 2. Mitochondrion  May be single or few in some cells, but most often a cell has hundreds or thousands of mitochondria.  Structure:  Rod-shaped organelles  Size ranges from being small to bigger sauge-like structure.  Has 2 membranes: 1. Outer membrane – smooth and separates mitochondria from the cytoplasm 2. Inner membrane – with an enfolding called Cristae (where important reactions in the mitochondria take place)
  20. 20. Mitochondria Generates energy (Power House of the Cell)
  21. 21. 3. Cytoskeleton Network of fibers floating through the cytoplasm Functions: a. Gives mechanical support to the cell b. Transport for some proteins and organelles c. Associated with motility
  22. 22. 3. Cytoskeleton Has 3 components:a. Microtubules – for movement (Ex: Cilia and Flagella)- contain Tubulinb. Microfilament – for muscle contraction- contains Actinc. Intermediate Filaments – reinforce the shape of the cell
  23. 23. 4. Vacuoles Mostly found in plant cells Fluid-filled sacs surrounded by a membrane Mature plant cells have a single large vacuole.  Plant Stem – cell sap
  24. 24. 5. Plastids Found in most plant cells Contain color pigments Two Kinds:  Chromoplast – colored plastids Ex: Chloroplast – contains chlorophyll  Leucoplast – colorless plastids; for storage of food substances
  25. 25. Ribosomes Tiny dot-like structures scattered throughout the cytoplasm Site where proteins are assembled “Protein Factories of the Cell”
  26. 26. Functions:1. Protects the cell from mechanical injury2. Gives rigidity to plant cell Cell wall is porous. Composed mainly of cellulose Also contains lignin