cell membrane

• importance of the cell membrane?

  Regulates what enters and exits the cell. enables cells to receive hormone messages. in chloroplast it contains the substance needed for photosynthesis.
• importance of the phospholipid structure in the cell membrane?


  help form the membrane that surrounds the cell. form a layer with their heads in the water and their tails out. if they're mixed with water, they from micelles and bilayers.
• what are micelles?

  ball like structures formed when phospholipids mix with water.
• what are bilayers?


  sheet like structures formed when phospholipids mix with water.
• what is the structure of micelles and bilayers?

  hydrophilic heads face outwards to shield hydrophobic tails.
• what is the fluid mosaic model?

  currently accepted model of membrane structure
• what describes the scattered proteins?

  mosaic
• why is it called fluid?

  because the phospholipids and proteins diffuse
• the fluid mosaic features?

  some phospholipids are saturated, and some aren't. the more saturated the more fluid the membrane is. as temperature decreases it becomes less fluid. proteins are found spanning the membrane.
• what are transmembrane proteins?

  proteins that span the membrane.
• what molecules does the membrane have?

  phospholipids, cholesterol, glycolipids, proteins and glycoproteins
• what is the role of phospholipids in the membrane?

  form a bilayer, affects the fluidity, they make it difficult for polar molecules to pass through the membrane.
• what is the role of cholesterol in the membrane?

  strengthens the membrane by getting between the phospholipids and reducing fluidity and prevents phospholipid tails to pack close together in cold temperatures.
• what is a cholesterol?

  a small molecule that's absent from prokaryotes.
• what would happen if cholesterol didn't exist?

  the membrane will break
• what are the types of glycoproteins/glycolipids and proteins in the membrane?

  receptors, cell to cell recognition, transport proteins, enzymes, cytoskeleton.
• what are glycoproteins and glycolipids?

  proteins and lipids that have carbohydrate chains attached to them.
• what is the role of receptor molecules?

  binds with particular substances, when the messenger molecule binds to the signaling receptor, chemical reactions start inside the cell.
• different cells have different?

  receptors
• what is the role of cell-to-cell recognition?

  allow cells to recognize each other and it's important for ingrowth and development and for immune responses.
• what is the role of transport proteins?


  provide hydrophilic channels for ions and polar molecules to pass through the membrane.
• what are the types of transport proteins?

  Channel proteins, carrier proteins.
• each transport protein is specific to a?

  type of ion
• what is the role of enzymes?


  catalyze hydrolysis of molecules
• what is the cytoskeleton?

  the proteins inside the cell membrane that're attached to a system of proteins.
• what is the role of the cytoskeleton?

  maintains the shape of the cell.
• what are other roles of the glycoproteins/glycolipids and proteins?

  proteins play roles in the membrane of organelles.
• an example of proteins that play roles in the membrane of organelles.

  photosynthesis in the chloroplast
• what does the hydrophilic head do in phospholipid molecules?

  shields hydrophobic tails from the water