Glucose, a small uncharged molecule, can pass through the cell membrane, but sodium ions do not pass through the membrane easily. what is the most accurate explanation for these findings? 1) cell membranes have carrier proteins for glucose but not for sodium.2) the cell membrane is semi-permeable.3) the membrane potential makes it difficult for sodium ions to diffuse across the membrane.4) the sodium-potassium pump keeps sodium inside the cell.

Imagine you are a student in alfred hershey and martha chase's lab in the late 1940's. you are given five test tubes with the e. coli bacteria that were infected with t2 bacteriophage that have been labeled with 32p or 35s. unfortunately, you forgot to label the tubes and are now uncertain which were 32p labeled and which were 35s labeled. you place the contents of each tube in a blender and pulse it for a few seconds to shear off the protein coats from the bacterial outer membranes. you then centrifuge the contents to seperate the protein coats and the bacterial cells. you then check for radioactivity and obtain the results shown below. which tubes contained e. coli infected with the phage labeled with 32p? select all tubes that apply.