Cells are the fundamental units of life, ranging from 0.0001 mm to 150 mm across. Robert Hooke discovered cells in 1665 while observing cork under microscope. Anton Van Leeuwenhoek observed cells moving under higher magnification
Chromosome is a package of DNA containing genetic material of an organism. DNA is coated with histones and nucleosomes during cell division. Chromosomes are visible only during metaphase, when aligned in cell center. Each chromosome has centromere and one or two arms
Organelle is a specialized subunit within a cell with specific function. Organelles can be membrane-bound or non-membrane-bound structures. Some structures extending outside cells are also considered organelles
Prokaryotic cells lack true nucleus and membrane-bound organelles. Found in domains Bacteria and Archaea, making up Earth's biomass. Smaller than eukaryotic cells, ranging from 0.1 to 5 micrometers. Contain DNA in nucleoid region and ribosomes
Cell membrane forms lipid bilayer separating cell contents from environment. DNA contains instructions for cell function, found in nucleus (eukaryotes) or cytoplasm (prokaryotes). Cytoplasm is viscous substance containing organelles and other cell components
Cells are basic building blocks of all living organisms. Cells contain genetic material and can multiply. Cells exist in various sizes, shapes, and types. Cells are made up of cell membrane, nucleus, and cytoplasm