Question | Answer |
term that describes the plasma membrane because it allows some substances to pass through while keeping others out | selectivey permeable |
the plasma membrane is an important structure for maintaining a steady state in the internal environment or | homeostasis |
What are the two major components of the plasma membrane | phospholipids and proteins |
Describe the phospholipids of a plasma membrane | a phospholipid is similar to a triglyceride except one fatty acid is replaced by a phosphate group.. making a polar head that interacts with water |
why does the phospholipid head interact with water | water is polar and the phospholipid head is polar and they like each other |
How are the phospholipids arranged in the plasma membrane | there are two layers called a phospholipid bilayer... they are arranged tail to tail ( the heads fact the exterior environment and the interior environment ( the environments are watery) |
What part of the phospholipid bilayer is farthest away from the water molecules | the nonpolar tails ( the interior portion) trys to stay away from water in the environments |
describe the barrier made by the phospholipid bilayer | the barrier is polar at its surfaces and nonpolar in the middle. Water soluble substances will not move easily through the plasma membrane... they are stopped by nonpolar middle |
There are many ? moving with and among the phospholipids | proteins |
an important protein in the plasma membrane that spans the entire membrane and makes tunnels allowing certain substances to enter and leave the cell.. | transport proteins |
where is the cholesterol of the plasma membrane located? Give a reason for this location | it is found among the phosopholipids .. the cholesterol is nonpolar and doesn't like water so it is away from the water in the middle of the membrane |
What is the function of the cholesterol in the plasma membrane? | helps prevent the fatty-acid tails of the phospholipid bilayer from sticking together.. which makes the membrane more fluid and not rigid |
Name 4 substances that is found in the plasma membrane | phospholipids, proteins, cholesterol, and carbohydrates (attached to proteins and stick out from the plasma membrane |
describe the carbohydrates in the plasma membrane | they are hooked to the proteins and stick out from the surface to the outer environment. They define the cell's characteristics and help cell's identify chemical signals |
describe the fluid mosaic model for the cell membrane | this refers to the plasma membrane and states that the phospholipids create a "sea" in which other molecules float.. and the various molecules make a pattern or mosaic on the surface.. |