Chapter 3 Vocabulary

Chapter 3 Vocabulary 1. Nucleus- innermost and is surrounded by a thin nuclear envelope 2. Cytoplasm- surrounds the nucleus and is itself encircled by an even thinner cell membrane (also called the plasma membrane) 3. Cell membrane- more than a simple boundary surrounding the cellular contents; it is an actively functioning part of the living material, and many important metabolic reactions take place on its surfaces 4. Selectively permeable- a membrane controls which substances exit and enter 5. Cytoplasm- contents of a cell, excluding the nucleus and cell membranes 6. Endoplasmic reticulum- organelle composed of a system of connected membranous tubules and vesicles along which protein is synthesized 7. Ribosome- organelle composed of RNA and protein that is a structural support for protein synthesis 8. Golgi apparatus- an organelle that prepares cellular products for secretion 9. Mitochondrion- organelle housing enzymes that catalyze reactions of aerobic respiration 10. Lysosomes- organelle that contains digestive enzymes 11. Centrosome- cellular organelle consisting of two Centrioles 12. Cilia / Flagella- microscopic, hair-like processes on exposed surfaces of certain epithelial cells 13. Vesicles- membranous cytoplasmic sac formed by infolding of cell membrane 14. Microfilament- tiny rod of actin protein in cytoplasm that provides structural support and movement 15. Microtubule- minute, hollow rod of the protein tubulin 16. Nuclear envelope- protein lined channels called nuclear pores that allow various substances to move between the nucleus and the cytoplasm 17. Nucleolus- small structure within cell nucleus that contains RNA and proteins 18. Chromatin-DNA and complex protein that condenses to form chromosomes during mitosis 19. Diffusion- random movement of molecules from region of higher concentration toward one of lower concentration 20. Equilibrium- state of balance between two opposing forces 21. Facilitated diffusion- diffusion in which carrier molecules transport substances across membranes from a region of higher concentration to a region of lower concentration 22. Osmosis- diffusion of water through selectively permeable membrane in response to concentration gradient 23. Isotonic- describes a solution with the same concentration of dissolved particles as the solution with which it is compared 24. Hypertonic- describes a solution containing a greater concentration of dissolved particles than the solution with which it is compared 25. Hypotonic- describes a solution containing a lesser concentration of dissolved particles than the solution to which it is compared 26. Filtration- movement of material across a membrane as a result of hydrostatic pressure 27. Active transport- process that uses metabolic energy to move a substance across a cell membrane, usually against the concentration gradient

28. Endocytosis- process by which a cell membrane envelops a substance and draws it into the cell in a vesicle 29. Exocytosis- transport of substances out of a cell in vesicles 30. Pinocytosis- process by which a cell engulfs droplets from its surroundings 31. Phagocytosis- process by which a cell engulfs and digests solid substances 32. Interphase- period between two cell divisions when a cell is carrying on its normal functions and prepares for division 33. Mitosis- division of a somatic cell to form two genetically identical cells 34. Prophase- stage of mitosis when chromosomes become visible 35. Chromosomes- rod like structure that condenses from chromatin in a cell’s nucleus during mitosis 36. Metaphase- stage in mitosis when chromosomes align in the middle of the cell 37. Anaphase- stage in mitosis when duplicate chromosomes move to opposite poles of cell 38. Telophase- stage in mitosis when newly formed cells separate 39. Differentiation- cell specialization due to differential gene expression