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Biology Chapter 5
Chapter 5 vocabulary 3
Term | Definition |
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Exocytosis | Transports macromolecules out of a cell via vesicle formation and often results in secretion. |
Transport vesicles | Membranous sac that enclose the molecules and keep them separate from cytoplasm. |
Vesicle formation | Take macromolecules that are to large to be moved by transport proteins, in and out of a cell. |
Transport proteins | Are involved in the passage of molecules and ions through the membrane. They often combine with a substance and help it move across the membrane, with an input of energy. |
Pumps | Proteins involved in active transport are often called pumps. Proteins use energy to move a substance against its concentration gradient. |
Sodium-potassium pump | Carrier protein in the plasma membrane that moves sodium ions out of and potassium ions into animal cells. Very important in nerve and muscle cells. |
Active transport | Requires metabolic energy (ATP) and moves substances across a membrane from an area of lower concentration to an area of higher concentration. In many cases, a transport protein acts as a pump that causes a substance to move against its concentration gradient. |
Bulk transport | Requires vesicle formation and metabolic energy It occurs independently of concentration gradients. |
Endocytosis | Transports macromolecules into a cell via vesicle formation. |
Receptor-mediated endoctytosis | Makes use of receptor proteins in the plasma membrane, in the coated pit. |
Pinocytosis | Occurs when vesicles form around a liquid or around very small particles. Examples: white blood cells, cells that line the kidney tubules, and the intestinal wall and plant root cells. |
Phagocytosis | If endocytosis material taken in is large, such as food particle or another cell, the process is called phagocytosis. It is common in single-celled organisms, such as amoebas. Also occurs in humans. |
Amoebas | A single-celled animal that catches food and moves about by extending finger like projections of protoplasm. Amoebas are either free-living in damp environments or parasitic. |
Protoplasm | The colorless material comprising the living part of a cell, including the cytoplasm, nucleus, and other organelles. |