60 CHAPTER 21 APPLICATION QUESTIONS AND PROBLEMS Introduction 20/The introductio
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60 CHAPTER 21 APPLICATION QUESTIONS AND PROBLEMS Introduction 20/The introduction to this chapter describes the long-term (a effects of famine on people conceived during the Dutch Hunger Winter. a. What evidence suggests that these are epigenetic effects? b. What additional evidence would help to demonstrate that these changes are due to epigenetic changes? Section 21.1 21. How do epigenetic traits differ from traditional genetic traits, such as the differences in the color and shape of peas that Mendel studied? Section 21.2 llhu nquired to prove that a phenotype isExplanation / Answer
Ans.20
a) Epigenetics is the study of heritable changes in gene expression (active versus inactive genes) that do not involve changes to the underlying DNA sequence — a change in phenotype without a change in genotype — which in turn affects how cells read the genes. Epigenetic change is a regular and natural occurrence but can also be influenced by several factors including age, the environment/lifestyle, and disease state.
The changes that took place during famine were phenotypically displayed in the child and their grandchild. The babies who were born small stayed small all their lives, with lower obesity rates than the general population. This concludes that they were epigenetic effects
b). For forty or more years, those people had access to as much food as they wanted, and yet their bodies never got over the early period of malnutrition.
More unexpectedly, the children whose mothers had been malnourished only early in pregnancy had higher obesity rates than normal. Recent reports have shown a greater incidence of other health problems as well, including effects on certain measures of mental health. Even though those individuals had seemed perfectly healthy at birth, something had happened to their development in the womb that affected them for decades after. And it wasn’t just the fact that something had happened that mattered, it was when it happened. Events that take place in the first three months of gestation, a stage when the fetus is really very small and developing very rapidly, can affect an individual for the rest of his or her life.
Even more extraordinarily, some of these effects seem to be present in the children of this group, that is, in the grandchildren of the women who were malnourished during the first three months of their pregnancy. So something that happened in one pregnant population affected their children’s children. That raised the really puzzling question of how those effects were passed on to subsequent generations.
Starving a pregnant mouse can cause changes in the sperm of her sons that apparently warp the health of her grandchildren, according to a new study. The finding offers some of the strongest evidence yet that a mother’s environment during pregnancy can alter the expression of DNA in ways that are passed on to future generations.
21. Traditionally genetic traits conceptually, deals with genes and gene function, while “epigenetics” deals with gene regulation. More specifically, genetics, for instance, Mendel described his studies on the allelic change which has contributed to the phenotypic changes like peas size, color etc. focuses on how DNA sequences lead to changes in the cell/host, while “epigenetics” focuses on how DNA is regulated to achieve those changes.
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