endocytosis

• • Some molecules are way too large to be taken into a cell by carrier proteins, e.g. proteins, lipids and some carbohydrates.
  • Instead a cell can surround a substance with a section of its plasma membrane.
  • The membrane then pinches off to form a vesicle inside the cell containing the ingested substance
  • the substance has been taken in by endocytosis
• Some cells also take in much larger objects by endocytosis - for example, some white blood cells use endocytosis to take in things like microorganisms and dead cells so that they can destroy them.
• Like active transport, this process uses ATP for energy.