The Cell Theory (usually credited to Schleiden, Schwann, and Virchow) has three major statements:
- All living organisms are composed of one of more cells. (Multicellular have a lot of cells, e.g. human beings; while unicellular organisms such as bacteria have a single cell)
- The cell is the basic unit of structure, function, and organization of living things. (It is the fundamental unit of life; much like a building block)
- All cells come from pre-existing cells. (Cells cannot just come out of nowhere. Cells are "off-springs" of other cells before them - born through cell division).
Parts of the Cell (present on both Animal and Plant cell unless otherwise specified):
- Nucleus - control center of the cell, holds the DNA
- Nucleolus - center of the cell, found inside the nucleus, produces ribosomal RNA (used for protein synthesis)
- Cell Membrane - semi-permeable membrane, controls what goes in and out of the cell
- Rough Endoplasmic Reticulum (ER) - contains ribosomes, for protein synthesis
- Smooth ER - no ribosomes, for lipid synthesis
- Cytoskeleton - framework of the cell, support and structure
- Golgi apparatus - packages protein (preparation for transport to destination)
- Cytoplasm - gel-like substance inside the cell, place for most cell processes
- Mitochondria - the power house of the cell, generate the cell's energy in the form of ATP.
- Lysosome (Animals) - 'suicide bag', degrades waste and other unnecessary substances in the cell
- Plastid (Plants) - carries out photosynthesis, storage of starch and fats
- Central Vacuole (Plants) - compartments for storage of waste or food
- Cell Wall (Plants) - rigid layer of cells outside the cell membrane, for structure and support of plants
- Centriole/Centromere (Animals) - participates in cell division of animal cells.