SECTION CELL MEMBRANE 3.3 Study Guide KEY CONCEPT VOCABULARY The cell membrane is a barrier that separates a cell from the external environment. cell membrane selective permea bility phospholipid re ce MAIN IDEA: Cell membranes ptor fluid mosaic model are composed of two phospholipid layers. 1. Draw a phospholipid in the box below. Label the three major parts. Phosphate group; glycerol; fatty acid c o o E o O .c + =co phospholipid is charged, or polar? the charoed oh OS o hate and qlvcerol 2. Which part of a 3. Which part of a phospholipid is nonpolar? 4. What type of molecules interact with water, polar or nonpolar? 5. Where the fattv acid tails does a cell membrane come into contact with water? G. 'Why do the phospholipids surrounding the ceil fbrm a ar outside the cell bilayer? the polar heads interact with water s o) f o T õ! J A cell membrane has other types of molecules embedded in the phospholipid bilayer. List function of each type of molecule in the table below. a o O) = o U o o c o) .E o o O Molecule Function 7. Cholesterol strengthen the cell membrane 8. Proteins nelp malenals cross tne memDrane, part oï cytosKeleton 9. Carbohydrates help rdentrly cell types Unit 2 Resource Book McDougal Littell Biology Study Guide I Name Period Date STUDY GUIDE, CONTINUED 1O. In what way is a membrane fluid? The phospholipids in each laver can move from side to side past each other, 11. Draw a picture in the box below to represent selective permeability. outside inside Refer to figure 3.18 for visual awnser MAIN IDEA: Chemical signals are transmitted across the cell membrane. 12. A receptor detects a signal molecule and carries out an action in response. 13. A ligand is a molecule that acts as a signal when it binds to a receptor. 14. A ligand that can cross 15. A ligand that cannot the cell membrane can bind to an intracellular receptor > c o cross the cell membrane can send a message to a cell by binding to membrane receptor, which then Ghanges oE o shape. .ç Ë Vocabulary Gheck =co c 16. What is the fluid mosaic model? T o) f o .õ = the fluid mosaic model is a description of the arrangement of the molecules that make up a cell mem bran6E J 17. The cell membrane allows some, but not all, molecules to cross. What term describes this property? selective permeability õo) f oo @ ! o) o o (_) 10 Study Guide Unit 2 Besource Book McDougal Litlell Biology