a. Progeria is caused by a gene that is responsible for the production of lamina A. This protein is usually in charge of providing structural support for the nuclear membrane that houses genes at the center of every cell. Those who have progeria also have defective lamina A, along with cells that deteriorate at rapid rates.
b. The Hayflick limit is the amount of times all human cells can reproduce until they re completely exhausted. The limit on cellular reproduction in humans is 52-60 times. This limit is caused by the loss of telemores, a genetic buffer at the ends of chromosomes. Telemores provides blank slots that can replace the bits of DNA that are gradually reduced as a cell divides. But a cell only has a limited amount of telemores, which directly limits the amount of cellular replication.
c. Cancer cells and stem cells are often dubbed as “immortal cells” because they have the ability to form at unprecedented rates. Both types of cells use telemerase to fix their telemeres in a lengthened state at the ends of chromosomes so that cell production can continue.
d. In mammals, the larger the natural size of a species is, the longer the average member of the species lives. This is partially due to larger animals having a superior ability in repairing DNA.
e. Risky childbirth is something that humans must endure due to evolutionary advantages. As humans evolved to have larger brains, it was necessary to have larger skulls for protection.This made childbirth risky, for human offspring with larger heads have to ease their way through a small birth canal, which can result into many complications. Furthermore, bipedalism requires females to have larger pelvis that is “twisted” in the middle, and widens at the point of the birth canal’s beginning.
29. Explain the author’s iPod and aging analogy.
The iPod analogy is used to describe the aging of organisms that are evolved to have shorter lives. If a particular species has a low life-expectancy and DNA errors, it pointless to solve those errors because it will not live to experience the effects. This is the same as not buying an extended warranty on an iPod that you only plan to keep for a week.
30. Identify the 5 lines of cancer defense.
1. There are specific genes responsible for tumor supression.
2. Certain genes call for specialized cancer hunters that are programmed to seek and destroy cells.
3. Some genes are responsible for repairing the genes that fight cancer.
4. Apostosis “convinces” dangerous cells to kill themselves.
5. The Hayflick limit supresses the number of times a cell can reproduce to the maximum of about 60 times.
31. What are the two accomplishments of biogenic obsolescence?
The first is clearing out older models for new ones, which means that there is more rrom for change, or evolution. Second, aging protects the group from contracting harmful parasites that can be passed on to future generations. A species can upgrade itself through sex and reproduction.
32. Compare and contrast the Savanna and aquatic ape hypotheses.
The savanna and aquatic ape hypotheses are two rivalry explanations that attempt to answer certain evolutionary changes in humans. In a general sense, the savanna hypothesis holds that our apelike ancestors migrated to the great grassy plains from forests because of climate change. Bipedalism was a result of having the ability to easily scan an area for food resources. Brave males who needed to hunt for their meals lost a lot of their hair so that they could cool down, because they tended to overheat. In comparison, the aquatic ape hypothesis attempted to explain an evolutionary cycle without centering around males. It suggested that humans spent time in both the water and land. Because standing upright allowed humans to venture into deeper water, bipedalism evolved. A prominent nose with nostrils on the bottom-side allowed humans to dive. Extra fat along the skin in humans provides warmth and keeps them afloat in water. Both hypotheses acknowledge the influence of water in the evolutionary traits of humans. The main difference is the hyped analysis surrounding males and the amount of water exposure and dependence throughout the pre-human lives.
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