Cytology Lecture PDF

Cytology Lecture #   Cytology Branch of Biology and medicine concerned with structure and function of the cells Organisms Unicellular Multicellular Organism organism   Level of organization The...

Cytology Lecture #   Cytology Branch of Biology and medicine concerned with structure and function of the cells Organisms Unicellular Multicellular Organism organism   Level of organization The biological levels of organization of living things arranged from the simplest to most complex are: organelle, cells, tissues, organs, systems, organisms   Chemical structure of the Cell Cell Water Inorganic materials Represent about 70% of cell weight Organic materials Act as solvent where all biochemical Ca2+,(PO4)3-,Na1+,and reaction occurs Mg2+ Carbohydrates Lipids Proteins Nucleic Acid Other mineral like Co2+,Cu2+,Cu3+,I1-,Mn2+,and Zn2+  Plasma Membrane: A thin membrane of a bout 0.005 µm (5nm) thickness. Usually surrounds every living cells and delimiting the cell from the environment around it.  Function of Plasma Membrane: 1. Act as a barrier by keeping the constituents of the cell in and unwanted substances out. 2. Gate which allow the transport of nutrients and waste products in and out of the cells  Ribosomes: Particles that synthesize proteins from amino acids Ribosomes are either free or bounded to endoplasmic reticulum “ER”  Endoplasmic Reticulum “ER”: Is a system of membranous vesicles extending through the cytoplasm. Endoplasmic Reticulum “ER” Smooth Endoplasmic Rough Endoplasmic Reticulum “SER” Reticulum ”RER”  Rough Endoplasmic Reticulum “RER”: Have ribosomes on their surface. A series of connected vesicles and flattened sacs.  Function of RER: RER usually found in the secretory cells and is responsible for the secretion that come out of the cell  Smooth Endoplasmic Reticulum “SER: Network of fine tubular membrane vesicles. Lack ribosomes  Function of SER: Lipid synthesis. Detoxification.  Golgi Apparatus (GA) : flattened, disk-shaped, membranous cisternae “ vesicles”, arranged in stack. Golgi is structurally polarized “ having two faces”: 1. Cis- Face : facing nucleus and where the transport vesicle fuses 2. Trans-face: facing the plasma membrane and where the secretory vesicle evolve.  Function of Golgi Apparatus : Maturation and activation of proteins.   Lysosomes: Bodies which bounded by a membrane. originate by budding from Golgi membranes. Lysosomes contain digestive enzyme that hydrolyze pro nucleic acids, lipids, carbohydrate.  Function of Lysosomes: Lysosomal enzymes fuses with the vacuoles containing worn- out organelles and material from inside or outside the cell to be digested.  Mitochondria: The power houses of the cells Mitochondrion has two membrane: 1. Outer membrane: smooth and have lipid and proteins. 2. Inner membrane : which has a large numbers of infoldings , or cristae. Mitochondria have a matrix “ mixture of enzymes and proteins and mitochondrial DNA.  Function of Mitochondria: The most important function of the mitochondria is to produce energy. The mitochondria also help in building certain parts of blood and hormones. Detoxify ammonia. The mitochondria also play important role in the process of apoptosis or programmed cell death.  Cytoskeleton: A fibrous network formed by different types of long protein filaments in the eukaryotic cell “ cells have a true nucleus” There are three major types of cytoskeletal filaments: 1. Microfilament “ Actin filaments” 2. Microtubules 3. Intermediate filaments  Function of Cytoskeleton: it creates a framework that organize other cell constituents and maintains the shape of the cell. Nucleus:  Nucleus: It is the control center of the cell that contain the genetic materials the transmitted to the offspring.