BIOLOGY 151 Lecture Notes - Lecture 3: Phosphorylation, Electrochemical Gradient, Osmosis

• School: UMASS-Amherst
• Department: Biology
• Course: BIOLOGY 151
• Professor: Kari Loomis

Document Summary

It"s how glucose ions and a multitude of other things enter cells. Hydrophilic phosphate heads face the outside and hydrophobic tails face the. Molecules move down their concentration gradient interior. This is the distribution of particles across a membrane that ranges from high to low concentration. Molecules from high to low naturally in order to reach equilibrium. Requires energy to move from low to high. Nonpolar molecules pass through the membrane easily. Molecules with a low permeability include: na+, glucose, and urea. These molecules are either too charged or too big to pass through the membrane. Molecules that pass through easier: h2o and co2. H2o is small and polar and co2 (passes easiest) is small and nonpolar. Proteins that transports certain molecules through the cell membrane and into the cytoplasm or extracellular fluid. The molecule attaches to the protein, the protein changes shape, and the molecule is moved across. Return to original shape after transporting the molecule.