Lec.3

• Nucleus : it contains the majority of the cell's genetic material

  it has spherical , oval or irrgeuler shape

  Located in the central regoins of cells
• Nucleus composed of the following

  1. nuclear envelope
  2. nucleoplasm
  3. chromatin
  4. nucleolus
• Nuclear envelope : bounded by two phospholipid bilayer membranes

  the outar membrane continous with endoplasmic reticulum , the outar and inner membrane fuse toghter to form gaps AKA nucler proes the space bettwen them filled with fluid

  the inner membrane is firmly attached to clumps of heterochromatin
• The nucleoplasm, karyoplasm or nuclear sap is a fluid filling the inside of the nucleus.

  Within this fluid both nucleolus (or sometimes nucleoli) and the chromatin are found
• Nucleolus:

  Nucleolus appears as a small dense body immersed in the nucleoplasm

  consist of rna and protien

  ribosomes synthisis protien
• Chromatin : the nucler matireal which is made up of DNA and large protiens moleculs (histones) this is basophilic in staining
• Chromatin has 2 types :

  1. euhormatin or noncondense chromatin : it is loosly packed thus lightly basophilic and metabolically active with regard to RNA syntheis
  2. heterochromatin or condense chromatin it is tightly packed thus its intensively basophilic and irs realtivly inactive metabolically and consist of chromosoms
• Cytoplasm : it is the space bettwen cell membrane and nucles it is composd of water , salt and protiens in eukaryotic cells and all organlles in eukaryotic cell such as the nucleus locted in the cytoplasm it has a highly organized structer
• Endoplasmic reticulum : it is a network of double membrane tubuler canals running throughout the cytoplasm a bounded ribosomes membrane refferd as smooth endoplasmic reticulum its function syntheis of lipids and varity of carbohydes , a heavily studded ribosomes membrane refferd as rough endoplasmic reticulum it can do the syntheis of protiens the diffrent products transport th the ER also it gives support to the cell dangerous chimicsls destroied by enzyms
• Golgi apparatus : it is a small irregular structure as flattend stacks of flattend membranes that is sitated near the middle of the cell this complex known as deliviry system as its collects , packges, distirbuts moleculs ,Transport vesicles bring the concerned material from the endoplasmic reticulum to Golgi

  apparatus. The formed material inside this apparatus are transported outside this

  apparatus through secretory vesicles. The number of these bodies in the cell depends

  on the activity of that cell. Golgi apparatus also forms lysosome bodies (lysosomes
• Ribosomes : are small assmbliies of protien 35% and ribosomal RNA 65% the rRNA is manfrctured by the DNA in nucleolus , it consist of large and subunit , some ribosomes are scattered , singly or clusters in the cytoplasm , they are concerd in syntheis of protiens
• Mitochondria


  Typically tubular or sausage-like organelles, bounded by two membranes. The outer one is smooth and the inner one is folded into numerous cristae. It is divided into two compartments: a matrix lying inside the inner membrane and an outer compartment or inner membrane space lying between the two membranes
• Matrix


  Compartment lying inside the inner membrane
• Outer compartment or inner membrane space


  Compartment lying between the two membranes
• Cristae


  Folded inner membrane
• ATP

  High energy compound
• Power house of the cell

  Mitochondria produce ATP
• Breakdown of organic compounds

  ATP is produced
• Mitochondria

  • Oxgyen and proteins are stored in ATP
• Liver and muscles

  • Use tons of mitochondria due to their high energy demands
• Centrioles : cylindrical structures that is composed of groupings of microtubles that are arranged as three in the circle of nine (3+9 pattren ) they occur in pair near the nucler membrane

  • they play an important rule in cell division , formation of cilia and flagella
• Lysosomes : enclosed membrane organells that is capeable of breaking down all the biological polymars such as protiens, nuclic acids, lipid and carbohydrate

  • its function as a digistive system of the cell serving both to degrade matiral in proccers called heterphagy
  • digest old celluer organlles in proccers called autophagy
• Peroxisomes: caaled microbodies they are similer to lysosomes in structer but they are smaller its name reffed to hydrogin peroxide that is producted by ny of

  oxidative enzymes

  • H2O2 is dangerous to cell
  • catalas enzyms breakdown hydrogin peroxide and turn it to harmless water and oxgen
  • peroxisomes are known as detoxifiers