Eukaryotic cells function

• Nucleus -

  Double membrane (nuclear envelope)

  Contains pores (molecules can enter + leave)

  Contains linear DNA associated with histone proteins (chromatin)

  Contains nucleolus - dense body + site of ribosome production
• 80s Ribosomes -

  Site of protein synthesis

  Found free in cytoplasm OR

  Attached to ER
• Rough ER:

  A system of membrane-bound, flattened sacs.

  Ribosomes are attached to the surface.

  Folds and processes proteins made on ribosomes
• Smooth ER -

  A system of membrane-bound sacs

  No attached ribosomes

  Produces lipids + steroids
• Mitochondria -

  The inner of its two membranes is folded to form projections, cristae.

  Site of later stages of aerobic respiration.
• Centrioles -

  Hollow cylinders made of a ring of nine microtubules.

  Involved in formation of spindle fibres in cell division

  + transport in cytoplasm
• Lysosomes -

  Vesicles with digestive enzymes

  Bound by a single membrane.

  Involved in the breakdown of unwanted structures

  Destroys whole cells, if they need to be replaced/during development

  Acrosome = specialised lysosome
• Golgi apparatus -

  Stacks of membrane-bound, flattened sacs

  Formed by fusion of vesicles from ER

  Modifies + packages proteins
• Which organelles are double-membraned?

  • Nucleus
  • Mitochondria
• Which organelles are single-membraned?

  • rER & sER
  • Golgi apparatus
  • Lysosome