Chapter 2: Problem 13

With increasing maternal age, the chances of observing trisomies increase significantly. Increasing paternal age is associated with de novo point mutations. Why?

Short Answer

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In summary, increasing maternal age is associated with a higher chance of observing trisomies because the decline in egg quality and quantity can cause chromosomal separation errors during cell division. Meanwhile, increasing paternal age is associated with de novo point mutations, as a higher number of cell divisions in spermatogenesis leads to a greater likelihood of DNA replication errors in sperm cells.

Step by step solution

Understand the concepts of trisomies and de novo point mutations

Trisomies are a type of chromosomal abnormality where there are three copies of a particular chromosome instead of the usual two. This can cause various disorders and complications. De novo point mutations, on the other hand, are genetic mutations that are not inherited from the parents but rather occur spontaneously in the individual.

Discuss the role of maternal age in trisomies

As women age, the quality and quantity of their eggs decline. This decline can cause errors in the separation of chromosomes during cell division, leading to an increased risk of abnormal embryos with trisomies. One well-known example is Down syndrome, which is caused by an extra copy of chromosome 21 and is more common in pregnancies of women over age 35.

Explain the effect of paternal age on de novo point mutations

In contrast to women, men constantly produce new sperm cells throughout their lives. However, the process of sperm production, known as spermatogenesis, involves many cell divisions. As men age, the number of these divisions increases, which in turn raises the risk of errors during DNA replication. These errors can result in de novo point mutations in the sperm, which can then be passed on to the offspring.

Summarize the reasons for the observed effects with increasing parental age

Increasing maternal age is associated with an increased risk of trisomies due to the decline in the quality and quantity of eggs, which can lead to errors in chromosome separation during cell division. On the other hand, increasing paternal age is associated with de novo point mutations because the number of cell divisions in spermatogenesis rises, resulting in a higher probability of errors during DNA replication in sperm cells.

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With increasing maternal age, the chances of observing trisomies increase significantly. Increasing paternal age is associated with de novo point mutations. Why?

Short Answer

Step by step solution

Understand the concepts of trisomies and de novo point mutations

Discuss the role of maternal age in trisomies

Explain the effect of paternal age on de novo point mutations

Summarize the reasons for the observed effects with increasing parental age

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