1. How often do mutations occur during DNA replication? How does the cell repair
ID: 48949 • Letter: 1
Question
1. How often do mutations occur during DNA replication? How does the cell repair these mutations? How do mutagens and carcinogens affect these processes and lead to the development of cancer?
2. BRCA1 and BRCA2 are genes that are normally involved in what cellular function? How do mutations in these genes predispose an individual to develop cancer?
3. Cancer is a genetic disease. Is cancer inherited? What is the difference between mutations that arise in somatic tissues versus germline tissues?
4. What is the difference between an oncogene and a tumor suppressor gene? How do they function normally? What happens when they are mutated?
5. What kind of mutation has occurred in the DNA of people with cystic fibrosis? How does the mutation affect the function of lung cells? Why would individuals that are heterozygous for CF have an advantage over normal individuals?
6. How are mutations inherited? How does the process meiosis differ from mitosis? What mechanisms during meiosis ensure that the genetic material passed on to offspring will be diverse?
7. What is the difference between dominant and recessive alleles? If the mutation that causes a disease is recessive how will it be inherited? Conversely if the mutation is dominant how will it be inherited?
Explanation / Answer
According to chegg rules we can answer only the first four questions.
1. Mutations can be spontaenous or can occur during the process of replication of DNA. A mistake occurs in replication once every 100,000,000 times. During replication, if mutation occurs, the replication process is stopped temporarily and cell cycle checkpoints are activated. Mutagens and carcinogens affect the proteins which play a role in the checkpoints. An example is p53 which is responsible for induction of apoptosis. IF this protein is mutated all the cells will be destroyed.
2. BRCA1 and BRCA2 are tumor suppressor genes. The protein produced from these genes plays a role in the repair of DNA. IF the DNA cannot be repaired, the mutated cells are destroyed. These genes are normally expressed in the breast. IF these genes which are responsible for DNA repair are themselves mutated, then DNA repair cannot be done and mutations will keep accumulating in cells. This may lead to cancer.
3. Yes, some types of cancer can be inherited. If mutations occur in somatic tissues they are not transferred to the next generation. The person who has the mutation suffers. But if the mutation occurs in the germline tissue, it is transferred to the next generation. This kind of transfer can cause cancer to run in families for generations.
4. An onogene has the ability to cause tumors or cancers. An oncogene is present as a proto-oncogene in the body. A proto oncogene usually takes part in signal transduction. They code for proteins which help in cellular growth. When a proto oncogene is activated it becomes an oncogene with the ability of rapid division as seen in cancer cells.
A tumor suppressor cell usually plays a role in DNA repair. They are called tumor suppressor cells because they prevent the accumulation of mutations which can cause cancer. When these are mutated, the DNA repair mechanisms do not work and cancer can occur.
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