The diffusion of Na+ is driven by their concentration gradient and by the attraction of cations to the negative side of the membrane. This Study Guide was developed by Volusia County teachers to help our students prepare for the Florida Biology End-Of-Course Exam. Water will move towards the outside of the cell. When you have completed the practice exam, a green submit button will appear. What does it mean that biological membranes are selectively permeable? Explain what is meant when we say a molecule is amphipathic. When you have completed the practice exam, a green submit button will appear.
In cotransport, a membrane protein couples the transport of two solutes. Exam Instructions: Choose your answers to the questions and click 'Next' to see the next set of questions. Chapter 7: Membrane Structure and Function. Grendel reasoned that cell membranes must be a phospholipid bilayer two molecules thick. The two layers may differ in lipid composition. Identify the letter of the choice that best completes the statement or answers the question. It is the diffusion of water through a selectively permeable membrane.
What four main classes do the large molecules of all living things fall into? As the plant cell loses water, its volume shrinks. Unlike lipids, carbohydrates, proteins, and nucleic acids are macromolecular chain-like molecules called polymers. Membrane models have evolved to fit new data. The receptor proteins are clustered in regions of the membrane called coated pits, which are lined on their cytoplasmic side by a layer of coat proteins. Membranes have distinctive inside and outside faces. Membrane carbohydrates are important for cell-cell recognition. Glycolipids are also produced in the Golgi apparatus.
Membranes are mosaics of structure and function. The large molecules of all living things fall into just four main classes. Some substances can pass across them and others cannot. Be sure to include which edition of the textbook you are using! If we see enough demand, we'll do whatever we can to get those notes up on the site for you! Water will move towards the outside of the cell. As temperatures cool, membranes switch from a fluid state to a solid state as the phospholipids pack more closely. Is the following sentence true or false? Net movement of water continues until the solutions are isotonic. Why does active transport require energy? This plasmolysis is usually lethal.
These channels open or close depending on the presence or absence of a chemical or physical stimulus. The cell becomes flaccid limp , and the plant may wilt. Water will move towards the inside of the cell. Chapter 7, Cell Structure and Function continued Osmosis pages 186—187 8. Which describes the inside of the cell and the direction of water? Plants use the mechanism of sucrose-proton cotransport to load sucrose into specialized cells in the veins of leaves for distribution to nonphotosynthetic organs such as roots. Specific proteins facilitate passive transport of water and selected solutes.
The inside of a cell contains more solutes than the outside of the cell. Water will move towards the inside of the cell. In the 1960s, the Davson-Danielli model of membrane structure was. Cell survival depends on balancing water uptake and loss. Membranes differ in thickness, appearance when stained, and percentage of proteins.
A phospholipid can travel the length of a typical bacterial cell in 1 second. Water will not move in either direction. Osmosis is the passive transport of water. . Eventually, the plasma membrane pulls away from the wall. Substances that move through the membrane do so at different rates. Holt McDougal Biology i Cell Structure and Function Study Guide B Cell Structure and Function.
Each protein in the membrane has a directional orientation in the membrane. If the membrane has microscopic pores that are large enough, dye molecules will cross the barrier randomly. Some ion pumps generate voltage across membranes. Click it to see your results. Click it to see your results. Membranes rich in unsaturated fatty acids are more fluid that those dominated by saturated fatty acids because the kinks in the unsaturated fatty acid tails at the locations of the double bonds prevent tight packing.
All included solutes are taken into the cell in this nonspecific process. Nicolson presented a revised model that proposed that the membrane proteins are dispersed and individually inserted into the phospholipid bilayer. Danielli proposed a sandwich model in which the phospholipid bilayer lies between two layers of globular proteins. The inside of the cell is negative compared to the outside. . .