Eukaryotic cell structure

• Cell surface membrane

  • regulates movement of substances in and out of the cell
  • features: phospholipid bilayer, cholesterol, glycoproteins, glycolipids, channel/peripheral/integral proteins
• Nucleus

  • contains genetic material that codes for proteins
  • surrounded by nuclear envelope with nuclear pores
  • contains the nucleolus which produces ribosomes/rRNA
  • contains the chromatin
• Mitochondria

  • the site of aerobic respiration, where ATP is produced
  • features: double membrane, the inner membrane is called the matrix which contains enzymes, and has many folds called cristae
• Chloroplasts

  • the site of photosynthesis
  • features: double membrane; thylakoids containing chlorophyll stack to form grana, which are joined together by lamellae; circular DNA and 70s ribosomes which allow protein synthesis; stroma; starch/lipid drops
• Ribosomes

  • the site of protein synthesis
  • floats freely in cytoplasm OR attached to RER
  • features: made up of proteins and RNA, 2 subunits
• Lysosomes

  • contains hydrolytic enzymes to digest invading cells and break down cellular waste
  • a type of Golgi vesicle
• Golgi apparatus

  • processes proteins and lipids, then packages them into Golgi vesicles, which are transported out of the cell via the cell membrane
  • synthesises lysosomes
  • features: a stack of flattened cisternae, vesicles
• Rough endoplasmic reticulum

  • folds and processes proteins made at the ribosomes
  • features: surface covered with ribosomes, formed by continuous folds of membrane continuous with the nuclear envelope
• Smooth endoplasmic reticulum

  • synthesises and processes lipids and carbohydrates (eg cholesterol, steroid hormones)
  • features: not studded with ribosomes
• Cell wall

  • provides structural support and shape to the cell
  • gaps allow exchange of substances with neighbouring cells
  • features: cellulose fibres, gaps known as plasmodesmata
• Cell vacuole

  • maintains turgor pressure, and isolates harmful chemicals from the rest of the cell
  • features: contains cell sap, surrounded by a thin membrane called the tonoplast