BOT 331 Exam 1 Questions with Correct Answers 2024 Graded A+

BOT 331 Exam 1 Questions with Correct Answers 2024 Graded A+ There are two types of nucleic acids: DNA and RNA. There is both DNA and RNA inside the nucleus, mitochondria and plastids. Is there both DNA and RNA in the cytosol? Explain your answer No, not both. DNA remains in the nucleus. RNA copies of genes are synthesized in the nucleus, but then moved out pores into the cytosol, where ribosomes (also containing RNA) bind RNA and use the RNA to direct synthesis of proteins. In the case of plastids and mitochondria, RNA copies of the organelle's genes remain in the organelle, and are translated into protein by ribosomes in the plastid stroma or mitochondrial matrix. The conducting cells of the xylem experience negative water pressures that could cause the cell's walls to collapse, but the walls typically resist collapsing. State two properties of a conducting cell's wall that resists collapse. The walls resist collapse because the walls are very thick. Most of the thickness is secondary wall that is dense with cellulose microfibrils and the phenolic polymer lignin, which is very rigid. The phenols of lignin also cross-link to microfibrils, strengthening the wall. the tension is what potentially could cause collapse and the thick, lignified walls resist the collapse. What is stress relaxation AND how does a cell cause stress relaxation? Stress relaxation is when microfibrils slide relative to each other, which relieves the tension that is otherwise pulling on microfibrils. Tension in the wall is due to the cell's turgor pressure. A cell causes relaxation by breaking the bonds between hemicellulose and cellulose, which allows the fibers to slide. A cell breaks the bonds by pumping protons into the wall (acidification), which activates a protein called Expansin. Expansin catalyzes breaking of the hemicelluose cross-links.