posted Jan 22, 2015, 1:19 PM by Jerrid Johansen
Here are the answers to the cell cycle test retake assignment.
- Page 278 #1a: Growth is limited because it is difficult to efficiently move materials in and out of the cell, and because a large cell is difficult for the DNA to control.
- #1b: As the size increases, the Surface Area to Volume Ratio decreases.
- #1c: The cell wants a lot of surface area (cell membrane) and not much volume (organelles) because it allows for an efficient flow of materials throughout the cell.
- Page 300 #1: D
- #2: A
- #4: Cell volume = the Organelles; Surface Area = Cell Membrane; Ratio of SA to Volume = Relative amount of cell membrane compared to the organelles inside the cell.
- Page 284 #2a: The cell cycle is a series of 8 steps that makes sure a cell properly grows and divides into two cells.
- #2b: Chromosomes are replicated during the S-Phase
- #3a: Prophase = Chromosomes condense; Metaphase = Chromosomes line up in the middle; Anaphase = Chromosomes pull apart; Telophase = Chromosomes move to opposite sides of the dividing cell.
- #3b: If the spindle fibers were disrupted during Metaphase, the chromosomes would not line up properly in the middle of the cell.
- Page 300 #9: C
- #10: B
- #12: The DNA condenses and changes from loose and stringy DNA, into packed and coiled Chromosomes.
- #14: Prophase, metaphase, aanaphase, metaphase
- #18: You seldom recover from spinal cord injuries because the cells divide so slowly. There is no chance for your cells to divide and replace the damaged cells.
- #19: They will remain in G1 phase
- Page 290 #2a: Cancer is a disease of the cell cycle because cancer cells go through all 8 steps, they just do so in an out-of-control way.
- #2b: They are similar because cell division will speed up in both cases. They are different in that for you knee scrape, the cell cycle will slow down once the injury has been healed. Cancer cells will stay in a faster state of growth and division.
- Page 301 #25: Cancer cells do not respond to all of the signals that closely regulate the cell cycle. They do what they want, and what they want to do is divide and divide and divide.
- #26: This happens in the p53 gene. Because of a mutation, the p53 gene becomes ineffective, and the cell with the damaged DNA is allowed to continue to grow and divide.
- Page 297 #2a: Stem cells are basically blank slates that can become multiple different cell types.
- #2b: Embryonic stem cells have the potential to become nearly any type of cell. Adult stem cells are limited in what they can become. Bone marrow stem cells can only become the different types of bloods cells. They cannot become something else.
- #3a: The benefit is that any cells that have been damaged, or have mutated in some way, can be replaced by the stem cells, which have the potential to become healthy cells.
- #3b: Scientists can now turn a normal body cell, like a skin cell, into an embryonic stem cell, which has the potential to become any other cell type. These are called Induced Pluripotent Stem Cells, or iPS cells.
- Page 302 #27: B
- #28: A
- #29: The blastocyst is a stage in the development of the embryo where pluripotent stem cells can be found
- #30: Cell differentiation is another name for specialization, and it allows multicellular organisms to develop complex tissues and organs that are capable of special functions.
- #31: iPS cells, and the ability to remove pluripotent stem cells from the embryo, without totally damaging the embryo.