세포학...레포트^^*

4-1. Prokaryotes and Eukaryotes. indicate whether each of the following statements is true (T) or false (F). If false, reword the statement to make it true. (a) Eukaryotic cells are in most cases larger than prokaryotic cells. (b) Some cells are large enough to be seen with the unaided eye. (c) Prokaryotic cells posses none of the following features:mitochondria, membrane-bounded nucleus, plasma membrane, microtubules. (d) The surface area/volume ratio is generally greater for a prokaryotic cell than for a eukaryotic cell. (e) The ribosomes found in the mitochondria of your muscle cells are more like those of the bacteria in your intestine than they are like the ribosomes in the cytosol of your muscle cells. (f) Because prokaryotic cells have neither mitochondria nor chloroplasts, they cannot carry out either ATP synthesis or photosynthesis. 4-3. Cellular Specialization. each of the cell types listed here is a good example of a cell that is specialized for a specific function. Match each cell type in list A with the appropriate function from list B, and explain why you matched each as you did. List A List B (a) Pancreatic cell Cell division (b) Cell from flight muscle Absorption (c) Palisade cell from leaf Motility (d) Cell of intestinal lining Photosynthesis (e) Nerve cell Secretion (f) Bacterial cell Transmission of electrical impulses 4-5. Matching. For each of the structures in list A, choose the single term from list B that matches best, and explain your choice. List A (a) Plant cell wall (f) Rough ER (b) Cyanobacterium (g) Smooth ER (c) Lysosome (h) Plasma membrane (d) Nuclear envelope (i) Virus (e) Nucleolus (j) Viroid List B Bacteriophage Pores Hydrolases Ribosome synthesis RNA Glycoprotein Cellulose Eukaryote Photorespiration Svedberg Lipid synthesis Glyoxysomes Muscle cells Granum Peptidoglycan Interphase Prokaryote Secretory proteins 4-10. Protein Synthesis and Secretion. Although we will not encounter protein synthesis and secretion in detail until later chapters, you already have enough information about these processes to place in order the seven events that are now listed randomly. Order events 1-7 so that they represent the correct sequence of events corresponding to steps a-g, tracing a typical secretory protein from the initial transcription (readout) of the relevant genetic information in the nucleous to the eventual secretion of the protein from the cell by exocytosis. Transcription━>(a)━>(b)━>(c)━>(d)━>(e)━>(f)━>(g)━>Secretion (1) The protein is partially glycosylated within the lumen of the ER. (2) The secretory vesicle arrives at and fuses with the plasma membrane. (3) The RNA transcript is transported from the nucleus to the cytoplasm. (4) The final sugar groups are added to the protein in the Golgicomplex. (5) As the protein is synthesized, it passes across the ER membrane into the lumen of a cisterna. (6) The enzyme is packaged into a secretory vesicle and released from the Golgi complex. (7) The RNA message associates with a ribosome and begins synthesis of the desired protein on the surface of the rough ER. 4-12. The Smallest Bacteria. The "smallest bacteria" mentioned on p.78 and in Problem 4-2 are called mycoplasma. Most mycoplasma are only about 0.3㎛ in diameter, which makes them the smallest known free-living organisms. To appreciate how small these cells are, answer the following.(The volume of a sphere and a cylinder are given by 4πr³/3 and πr²h,respectively.) (a) What is the internal volume of a mycoplasma cell in milliliters? How does this compare with the internal volume of Escherichia coli,a common intestinal bacterium, which is a cylinder with a diameter if 1㎛ and a length of 2㎛? (b) How many ribosomes can a mycoplasma cell accommodate of ribosomes can occupy no more than 20% of the internal volume of the cell? How does this compare with the thousands of ribosomes present in an E.coli cell? (c) Assuming that the concentration of glucose in a typical mycoplasma cell is 1.0 mM, how many molecules of glucose are present in the cell? (d) Most compounds are present in cells at much lower concentrations than glucose, The concentrations than glucose. The concentration of a substance called NAD(for nicotinamide adenine dinucleotide) in a bacterial cell is typically about 2mM. How many molecules of NAD are present in a mycoplasma cell? (e) A typical mycoplasma cell has as its genetic information a single DNA molecule with a molecular weight of about 2 * 10 and a circumference of about 100nm. What fraction of the weight of a mycoplasma cell does its DNA molecule represent? (Assume the density of a mycoplasma cell to be 1.1 g/cm³) What, if any, problem might the length of the DNA molecule pose for the cell? (f) Based on your calculations, what do you think might be the factor(s) that set the lower limit on the size of a cell?