science
...ic unit of mass. Celsius scale - (C) metric temperature scale on which water freezes at 0° and boils at 100°. 5-1 The Cell Theory 1. cell - the basic unit of structure and function in living things. 2. cell theory - the understanding that all living things are composed of cells and that all cells come from preexisting cells. 5-2 Cell Structure 3. cell membrane - cell structure that regulates the passage of materials between the cell and its environment; aids in the protection and support of the cell. 4. cell wall - cell structure that surrounds the cell membrane for protection and support in plants, algae, and some bacteria. 5. nucleus - the organelle that controls the cells activities and contains DNA. 6. eukaryote - organism made up of cells that have a nucleus. 7. prokaryote - single-celled organism whose cell does not have a nucleus. 8. nuclear envelope - membrane that surrounds the nucleus of a cell. 9. nucleolus - cell structure that contains RNA and proteins. 10. chromosome - threadlike structure in a cell that contains the genetic information that is passe on from one generation of cells to the next. 11. cytoplasm - area between the nucleus and cell membrane of a cell. 5-3 Cytoplasmic Organelles 12. organelle - cell structure that performs a specialized function within the cell. 13. mitochondrion - organelle that changes chemical energy stored in food into compounds that can be used by the cell. 14. chloroplast - organelle that converts sunlight into chemical energy in plants. 15. ribosome - organelle in which proteins are made. 16. endoplasmic reticulum - complex network that transports materials throughout the inside of a cell. 17. Golgi apparatus - organelle that modifies, collects, packages, and distributes molecules made at one location of the cell and used at another. 18. lysosome - organelle that contains chemicals and enzymes necessary for digesting certain materials in the cell. 19. vacuole - organelle that stores materials such as water, salts, proteins, and carbohydrates. 20. plastid - plant cell organelle involved in the storage of food and pigments. 21. cytoskeleton - framework of the cell composed of a variety of filaments and fibers that support cell structure and drive cell movement. 5-4 Movement of Materials ...