The generalised cell

• Cytoplasm

  • Jelly like material inside a cell
  • Fills up all the space between the nucleus and the cell membrane
  • Made up of cytosol and organelles
• Cytosol

  • The liquid part of the cytoplasm
  • 75%-90% water
  • Mixture of salts and carbohydrates dissolved in it
  • Proteins and fats do not dissolve
  • Metabolic reactions occur here
  • Control the flow of chemicals in and out of the cell
• Cell membrane

  • Also known as the plasma membrane
  • Separates the cells contents from the environment outside
  • It is able to control what enters and leaves the cell
• Cytoskeleton

  • An internal scaffolding of protein fibres with in the cytoplasm
• Inclusions

  Chemical substance of granules in cytoplasm
• Nucleus

  • Cells usually contain a single nucleus
  • Liver cells have two or more
  • Red blood cells have none
  • Surrounded by a nuclear membrane (double membrane)
  • Nuclear pores allow RNA to enter and exit the nucleus
  • DNA is stored in here
• • Nucleolus
  • It’s a small part of the nucleus involved in protein synthesis
• Endoplasmic reticulum

  2 types:

  1. rough - has ribosomes, involved in protein synthesis
  2. smooth - has no ribosomes, involved in enzyme synthesis

  • A vast network of membrane channels
  • They allow a surface for chemical reactions
  • It provides a calal for connecting the cells interior and exterior
• • Ribosomes
  • Small spherical structures involved in protein synthesis
• Mitochondria

  • Known as the powerhouse of the cell as they are the site of cellular respiration
  • They are capable of cell replication as they contain their own set of DNA
• Golgi apparatus/body

  • A series of flattened membranes stacked one upon the other
  • It modifies proteins and packages them to be secreted from the cell
  • Proteins are produced at the ribosomes that pass through the ER to the Golgi
  • Small sacs of liquid that have proteins inside are formed at the edge of the Golgi
  • These sacs are surrounded by a membrane and are called vesicles
• Lysosomes

  • Storage vessels for powerful digestive enzymes
  • They fuse with vesicles containing substances for phagocytosis
• • Centrioles
  • A pair of bar-like cylinders that produce spindle fibres upon which chromosomes travel to opposite poles of a dividing cell during cell divison