Cells

• • considered as the cell's command center

  nucleus
• contain the genes: the unit of hereditary material

  nucleus
• associated with very important macromolecules

  • nucleic acids
  • DNA of the genes
  • RNA of the nucleoli
• system of tubules and flattened sacs continuous with the nuclear membrane providing the cell with its internal support

  endoplasmic reticulum
• endoplasmic reticulum associated with ribosomes on the cytoplasmic side of the membrane and size according to the quantity of protein which cell "exports"

  Rough ER
• endoplasmic reticulum without ribosomes and synthesizes proteins for cell's own use

  Smooth ER
• considered the cell's protein factories

  ribosomes
• made up of two unequal subunits, each containing RNA

  ribosomes
• sites for the synthesis of protein

  ribosomes
• largest cytoplasmic organelles and considered the cell's power plants

  mitochondria
• provided with a smooth outer membrane and folded inner membrane, the folds are called cristae


  mitochondria
• considered as a self-regulating organelle, since it synthesizes its own proteins and is self-duplicatingdue to the presence of mitochondrial DNA and RNA

  mitochondria
• controls concentration of water, calcium, an othe ions in the cytoplasm; breakdown and recycling of sugars, fatty acids, and amino acids

  mitochondria
• flat, membranous sacs, and vacuoles considered as packages of cell's proteins

  golgi apparatus
• responsible for concentrating and wrapping certain enzymes into separate organelles which remain inside the cell

  golgi apparatus
• considered as the scavengers of the cell

  lysosomes
• referred to as bags of enzymes, suicide bags, or graveyard of the cell

  lysosomes
• principal site of intracellular digestion

  lysosomes
• not membrane-bound; for transport of materials, cell movement, and cell support

  microtubules and microfilaments
• considered as the cell's delicate but tough "guardian"

  cell membrane
• composed of lipids, proteins, and oligosaccharides

  cell membrane
• regulates the translocation of materials

  cell membrane
• Cell Macromolecules of the ff are:

  • Nucleus: nucleic acids, proteins, lipids
  • ER: lipids, proteins
  • ribosomes: RNA, proteins
  • mitochondria: proteins, lipids, CHO, nucleic acids
  • golgi apparatus: proteins, lipids, CHO
  • lysosomes: proteins
  • cell membrane: lipids, proteins, CHO
• the cell (protoplasm)is a combination of true and a colloidal solution since some of its components are insoluble while others are soluble in its water medium
• The following are colloidal properties of the cell

  • filterability
  • negligible osmotic pressure
  • tyndall phenomenon
  • brownian movement
  • electrical charges
  • surface tension
  • osmosis
  • diffusion
  • dialysis
• water is an essential substance for plant and animal groeth
• water is essential to life and is in solvent water that the chemical reactions of biological processses evolved
• Molecular composition of cell

  • water accounts for about 70-75% of the weight of the cell
  • organic compounds accounts for 25-30% of the cell weight
  • they are nucleic acids, proteins, polysaccharides (carbohydrates) and lipids
  • inorganic compounds account for the rest of the cell weight
• prokaryotes (eubacteria and archaebacteria) are the most abundant organisms on earth
• a prokaryotic cell does not contain a membrane-bound nucleus
• each prokaryotic cell is surrounded by a plasma membrane
• the cell has no subcellular organelles, only infoldings of the plasma membrane called mesosomes
• the DNA is of prokaryotic cell is condensed within the cytosol to form the nucleiod
• some prokaryotes have tail-like flagella
• diffusion is the movement of a substance from an area of its higher concentration to an area of its lower concentration
• simple diffusion is the type of diffusion of dissolved sollutes through the plasma membrane
• facilitated diffusion is the type of diffusion that requires a protein carrier
• osmosis is the diffusion of water point across a selectively permeable membrane
• eukaryotic cell characteristics:

  • DNA is found in the nucleus of the cell
  • contains membrane-bound organelles which include mitochondria, endoplasmic reticulum, and golgi apparatus
  • cell division involves mitosis
• prokaryotic cell characteristics:

  • DNA is not enclosed within the membrane
  • lack membrane-enclosed organelles
  • usually divide by binary fission