| A | B |
|---|
| plasma membrane | A barrier that surrounds the cell and functions in controlling what goes in and out of the cells and in the passage of chemical messages to and from the cell. |
| phospholipid bilayer | A double layer of phospholipid with hydrophillic phosphate heads and hydrophobic lipid tails. |
| glycoprotein | A protein with carbohydrates attached. Functions in the regulation of the movement of substances across the cell membrane and in cell to cell communication and recognition. (Part of marker protein) |
| transport proteins | Proteins in the cell membrane that regulate the movement of water soluble molecules. |
| channel proteins | Forms pores or channels that allow small water soluble molecules to pass through the plasma membrane. |
| carrier proteins | Have binding sites that can grab onto specific molecules on one side of the membrane. The protein changes shape and moves the molecules across the cell membrane. |
| receptor proteins | Triggers cellular responses when specific molecules in the extracellular fluid binds to them. |
| recognition proteins | Many are glycoproteins, serve as identification tags and cell surface attachment sites. (also called marker proteins) |
| concentration gradient | A difference in concentration between one region and another region. |
| passive transport | Substance move down a concentration gradient from [high] to [low] without the use of energy. |
| active transport | Movement of substance via transport proteins against a concentration gradient from [low] to [high] with the use of energy. |
| diffusion | The net movement of molecules down a concentration gradient from [high] to [low]. Can be a solid, liquid, or gas. |
| simple diffusion | The easy passage of substances across the phospholipid bilayer. |
| facilitated diffusion | Molecules can only diffuse across the cell membrane with the aid of channel or carrier proteins. |
| osmosis | Movement of water from regions of [high] to regions of [low] across a membrane. |
| isotonic | The concentration of solutes and water in the same outside and inside the cell. |
| hypertonic | The concentration of solutes in the environment is higher than inside the cell, thus the concentration of water is lower in the environment than inside the cell. Water moves out of the cell and the cell shrinks. |
| hypotonic | The concentration of solutes in the environment is lower than inside the cell, thus the concentration of water is higher in the environment than inside the cell. Water moves into the cell and the cell expands. |
| turgor pressure | The pressure of water in the central vacuole pushes the fluid portion of the cytoplasm up against the cell wall. |
| contractile vacuoles | Organelles in microorganisms that regulate water in the cell by removing excess water. |
| endocytosis | The plasma membrane engulfs fluid droplets or particles from outside the cell and pinches of a membranous sac called a vesicle inside the cell. |
| phagocytosis | The engulfing of large particles, including whole microorganisms by endocytosis. |
| pinocytosis | The engulfing of small particles or liquids by endocytosis. |
| exocytosis | The removal of waste, or secretory materials by a process that is the reverse of endocytosis. |
| homeostasis | A biological balance between a cell or an organism and its environment. |
