Ch. 11 - Gene Mutation, DNA Repair, and Homologous Recombination

Sanders - Genetic Analysis: An Integrated Approach 3rd Edition

Sanders3rd EditionGenetic Analysis: An Integrated ApproachISBN: 9780135564172당신이 사용하는 게 아니라요?교과서 변경

Sanders 3rd Edition

Ch. 11 - Gene Mutation, DNA Repair, and Homologous Recombination

문제 C.3a

11장, 문제 C.3a

For the retinal cancer retinoblastoma, the inheritance of one mutated copy of RB1 from one of the parents is often referred to as a mutation that produces a 'dominant predisposition to cancer.' This means that the first mutation does not produce cancer but makes it very likely that cancer will develop. Define the 'two-hit hypothesis' for retinoblastoma.

검증된 단계별 안내

The 'two-hit hypothesis' is a model proposed to explain the development of retinoblastoma and other cancers caused by tumor suppressor gene mutations. It suggests that two genetic 'hits' or mutations are required to inactivate both copies of a tumor suppressor gene, such as RB1, leading to cancer.

Step 1: Understand that individuals with a hereditary predisposition to retinoblastoma inherit one mutated copy of the RB1 gene from a parent. This is the first 'hit,' which is present in all cells of the body (germline mutation).

Step 2: The second 'hit' occurs as a somatic mutation in a retinal cell during the individual's lifetime. This mutation inactivates the remaining functional copy of the RB1 gene in that specific cell.

Step 3: When both copies of the RB1 gene are inactivated in a retinal cell, the cell loses its ability to regulate the cell cycle properly, leading to uncontrolled cell division and tumor formation.

Step 4: The 'dominant predisposition' arises because individuals with one inherited mutation (first hit) are much more likely to acquire the second mutation in a retinal cell, making the development of retinoblastoma highly probable.

비슷한 문제에 대한 검증된 영상 답변:

이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.

영상 길이:

주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Two-Hit Hypothesis

The two-hit hypothesis, proposed by Alfred Knudson, suggests that cancer develops through a two-step process involving mutations in tumor suppressor genes. In the case of retinoblastoma, the first 'hit' is a hereditary mutation in one copy of the RB1 gene, which predisposes individuals to cancer. The second 'hit' is typically a somatic mutation that occurs in the other copy of the gene, leading to the loss of function necessary for tumor suppression and resulting in cancer development.

Tumor Suppressor Genes

Tumor suppressor genes are critical for regulating cell growth and preventing uncontrolled cell division. The RB1 gene, which encodes the retinoblastoma protein, is a key tumor suppressor that helps control the cell cycle. When both copies of the RB1 gene are mutated, the regulatory function is lost, allowing cells to proliferate uncontrollably, which can lead to cancer.

Dominant Inheritance

Dominant inheritance refers to a pattern where only one mutated copy of a gene is sufficient to express a trait or predisposition to a condition. In retinoblastoma, inheriting one mutated RB1 gene from a parent results in a dominant predisposition to develop cancer, as the individual is at a higher risk of acquiring the second mutation necessary for tumor formation. This concept is crucial for understanding the genetic basis of familial retinoblastoma.

관련 실천

교과서 질문

What is the difference between a transition mutation and a transversion mutation?

1141

views

교과서 질문

Nitrous acid and 5-bromodeoxyuracil (BrdU) alter DNA by different mechanisms. What type of mutation does each compound produce?

603

views

교과서 질문

Identify two general ways chemical mutagens can alter DNA. Give examples of these two mechanisms.

655

views

교과서 질문

What are the differences between a synonymous mutation, a missense mutation, and a nonsense mutation?

916

views

교과서 질문

UV irradiation causes damage to bacterial DNA. What kind of damage is frequently caused and how does photolyase repair the damage?

788

views

교과서 질문

In March 2011 an earthquake measuring approximately 9.0 on the Richter scale struck Fukushima, Japan. Several nuclear reactors at the Fukushima Daichii Nuclear Power Plant were damaged, and nuclear core meltdown occurred. A massive release of radiation accompanied damage to the plant, and 5 years later the incidence of thyroid cancer in children exposed to the radiation was determined to be well over 100 times more frequent than expected without radiation exposure. DNA damage and mutations resulting from radiation exposure are suspected of causing this increased cancer rate. Do you think it is possible that significant increases in the incidence of other types of cancer will occur in the future among people who were exposed to the Fukushima radiation? Why?

466

views