| 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 heads and hydrophobic 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. |
| transport proteins | Proteins in the cell membrane that regulate the movement of water soluble molecules. |
| channel proteins | Forms pores or channels that allow samll 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. |
| desmosomes | Hold adjacent cells together by using proteins and carbohydrates as glue. |
| tight junctions | Leakproof. Spaces between the cells that line tubes or sacs are sealed with strands of proteins. |
| gap junctions | Commononly found in animals. Pores or channels that connect the insides of adjacent cells. |
| plasmodesmata | Found in all plant cells. Cytoplasmic strands, surrounded by plasma membrane that pass through openings in walls of adjacent plant cell. Forms a continuous bridge between neighboring cells. |
| 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. |
| differentially permeable | Allows some molecules to pass through or permeate, but prevent other molecules from passing. |
| 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]. |
| 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. |
| 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. |
| turgor pressure | The pressure of water in the central vacuole pushes the fluid portion of the cytoplasm up against the cell wall. |
| plasmolysis | The shrinking or wilting of the central vacuole due to low turgor pressure. |
| cytolysis | The bursting of a cell due to extremely high turgor pressure. |
| 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. |
| receptor mediated endocytosis | Substances accumulate in a depression of the plasma membrane called coated pits. the coated pits deepens into a u-shaped pocket that pinches off into the cytoplasm as a coated vesicle. |
| 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. |
