Chapter Questions
Which structure is generally present in both prokaryotic cells and eukaryotic plant cells?a. Chloroplastsb. Cell wallc. Nucleusd. Mitochondriae. Microtubules
The major factor limiting cell size is thea. concentration of water in the cytoplasm.b. need for energy.c. presence of membrane-enclosed organelles.d. ratio of surface area to volume.e. composition of the plasma membrane.
Which statement about plastids is true?a. They are found in prokaryotes.b. They are surrounded by a single membrane.c. They are the sites of cellular respiration.d. They are found only in fungi.e. They may contain various pigments or polysaccharides.
Which structure is not surrounded by one or more membranes?a. Ribosomeb. Chloroplastc. Mitochondriond. Peroxisomee. Vacuole
The cytoskeleton consists ofa. cilia, flagella, and microfilaments.b. cilia, microtubules, and microfilaments.c. internal cell walls.d. microtubules, intermediate filaments, and microfilaments.e. calcified microtubules.
Microfilamentsa. are composed of polysaccharides.b. are composed of actin.c. allow cilia and flagella to move.d. make up the spindle that aids the movement of chromosomes.e. maintain the position of the chloroplast in the cell.
If all the lysosomes within a cell suddenly ruptured, what would be the most likely result?a. The macromolecules in the cytosol would break down.b. More proteins would be made.c. The DNA in mitochondria would break down.d. The mitochondria and chloroplasts would divide.e. There would be no change in cell function.
Through how many membranes would a molecule have to pass in moving from the interior (stroma) of a chloroplast to the interior (matrix) of a mitochondrion? From the interior of a lysosome to the outside of a cell? From one ribosome to another?
Compare the extracellular matrix of the animal cell with the plant cell wall, with respect to composition of the fibrous and nonfibrous components, rigidity, and connectivity of cells.
The drug vincristine is used to treat many cancers. It apparently works by causing microtubules to depolymerize. Vincristine use has many side effects, including loss of dividing cells and nerve problems. Explain why this might be so.
The movements of newly synthesized proteins can be followed through cells using a "pulse-chase" experiment. During synthesis, proteins are tagged with a radioactive isotope (the "pulse"), and then the cells are allowed to process the proteins for varying periods of time. The locations of the radioactive proteins are then determined by isolating cell organelles and quantifying their levels of radioactivity. What results would you expect for (a) a lysosomal enzyme and (b) a protein that is released from the cell?