Question

Question 9 1 pts Why are inherited forms of cancer autosomal dominant but not fully penetrant? Even if the mutation is inherited, a loss-of-funciton mutation ipmscting one allele is not expressed The inherited allele is dominant at the cellular level, but might not be expressed depending on genetic background Most inherited mutations are recessive at the cellular level Sporadic, but not inherited forms of cancer forms of cancer are caused by somatic mutation Question 10 1 pts Select true statements regarding clonal nature of tumnors All cells in tumor originated from the same cell O All cells in tumor have the same assortment of mutations O All mutations in a tumor cell contribute to how invasive/proliferative the cell is O A single mutation is sufficient to produce a clonal cell expansion in a tumor

Answer 1

Qstn 9:

Answer is optn A) AND B)

Explanation:   Meaning of 'cancer is autosomal dominant'----

• Autosomal- There is some mutation on one of the autosome. Thus either male or female can inherit that gene, because autosomes are not sex related.
• Dominant- Mutated gene can be passed on through either mother or father. A single allele is enough to cause the disease.
• Thus if a father has a cancer gene , he can pass it on to his son/daughter.  Its highly possible that they are not showing any symptoms of cancer, just carrying the gene. It is 50;50 chance scenario. The child will have cancer or not.

This pattern is dominant in nature but still has low penetrance.

Penetrance:  Phenomenon when a particular genotype ids inherited from parents and is also expressed as phenotype.

Incomplete / Half penetrance: Even though the genotype is inherited, it couldn't be expressed as phenotype. Example: If 2 identical twins possess genotype for rolling of tongue, yet only one can actually do it. This indicates Incomplete penetrance. Genotype is present but wont be expressed.

To answer your qstn, cancer is a dominant autosomal disease, but it shows incomplete penetrance because many factors will play a role in expression. example- lifestyle, exercise habits, gene combination and some environmental factors too. But this person can still transmit the gene to his/her Offsprings.

Question 10:

A) YES.Word 'clone' itself means identical cells with common ancestry. Thus all cells in tumour originate from same cell.

B) NO. all cells are abnormal in a tumor and it is not always the case that they have same mutations.Tumors are known for their genetic instability

C)Yes. mutations will decide the invasiveness and proliferation of the tumor

D)NO. A single mutation is not enough as we have many mechanisms to check for abberations. A series of mutations are required.

Answer is optn A) and B)