b.A larger surface to volume ratio allows for faster cell growth, as seen in the growth rate of bacteria cells compared to human cells. Because human cells have a higher volume, they also need more nutrients to be transported through the plasma membrane. The membrane can only supply these nutrients at a limited speed, lowering the potential growth speed and raising the doubling time.
2.) a. 45 generations (including original) would be needed to match the number of cells in an adult human (10^13).
b. Because each cell divides once a day and the the total number of cells doubles each day, it would take 44 days to produce 10^13 cells.
c. It takes human much longer than 44 days to develop into adults for several reasons. The first being that some cells will die during development, increasing the amount of time needed to reach a certain total. Also, cells grown in a lab are provided with a prime amount of nutrients for growth, while cells in the body are dependent on the organism to provide the necessary nutrients. Another reason is that cells are programmed against constant division, as to avoid uncontrollable growth and ultimately to avoid cancer.
3.) The nucleus does a lot of things for eukaryotic cells. Mainly, it protects the cell's DNA from damage that could be otherwise inflicted by various materials found throughout the cytoplasm. If the cell were not encased within the nucleus, not only would the DNA be at risk but other processes occuring within the cell would be at risk as well. The reason DNA is seperated from the cytoplasm in eukaryotic cells is because of its long and linear nature. This makes interference between the two highly detrimental to the cell.
4.) Proteins lacking a sorting signal will not be able to reach its proper destination, and therefore will eventually be degraded by other proteins within the cell.
5.) No, not all human cells contain the same set of organelles.