Pinocytosis or 'cell drinking' is one of three forms of endocytosis, a cellular process that is used to take up smaller particles in cell by splitting in small particles , and forms vesicles which then merge with lysosomes to hydrolyze (hydrolytic enyzmes) to break down the particles. It requires ATP. Also known by the uptake of materials into cells by means of invagination of the plasma membrane by dissolving the material. Endocytosis is a process whereby cells absorb material (molecules or other cells) outside their cell membranes. ... Cells in culture, stained for keratin (red) and DNA (green) The cell is the structural and functional unit of all living organisms, sometimes called the building blocks of life. ... In cell biology, a vesicle is a relatively small and enclosed compartment, separated from the cytosol by at least one lipid bilayer. ... Lysosomes are organelles that contain digestive enzymes (acid hydrolases) to digest macromolecules. ... Adenosine triphosphate (ATP) is the nucleotide known in biochemistry as the molecular currency of intracellular energy transfer; that is, ATP is able to store and transport chemical energy within cells. ... Invagination is one of the morphogenetic processes by which an embryo takes form, and is the initial step of gastrulation, the massive reorganization of the embryo from a simple spherical ball of cells, the blastula, into a multi-layered organism, with a differentiated endoderm, mesoderm, and ectoderm. ... Drawing of a cell membrane A component of every biological cell, the cell membrane (or plasma membrane) is a thin and structured bilayer of phospholipid and protein molecules that envelopes the cell. ...