essay q's

What does it mean to have a genetic predisposition to cancer?

If you inherit mutations in genes like p53, Rb, or DNA repair genes, you already have some of the mutations required for cancer to develop. Since cancer requires multiple mutations, starting with inherited ones means cancer can develop sooner than it would in someone without them.

Why would mutations in cell adhesion proteins be found in many cancers?

Cells should only divide when properly attached to neighboring cells. Mutations in adhesion proteins can fool cancerous cells into behaving as though they are still attached, allowing them to detach and travel through the body to seed new tumors elsewhere. This process is called metastasis.

What do tumor suppressor genes do and what happens when they are mutated?

Tumor suppressor genes stop cell division when something is wrong such as DNA damage. When mutated, they lose this braking function, allowing cells to divide under abnormal conditions, which increases the likelihood of additional mutations accumulating.

What is the normal role of proto

oncogenes vs. tumor suppressor genes?

What does it mean that tumors are genetically heterogeneous and why does it make treatment harder?

Each cancer cell independently accumulates new mutations as the tumor grows, so different cells within the same tumor carry different mutations. A drug targeting one specific protein may kill some tumor cells but leave others with mutations in that protein completely unaffected.

Name two environmental factors that can cause cancer regardless of genetic makeup.

UV radiation can cause skin cancers because skin is directly exposed to it. Tobacco smoke can cause cancers of the lungs and mouth and throat.

Why do inherited mutations in DNA repair genes like BRCA1 and BRCA2 increase cancer risk even though they do not directly control the cell cycle?

DNA must be undamaged before it is replicated. If a person cannot repair certain types of DNA damage, cells accumulate new mutations every time they divide. Over time these additional mutations are more likely to hit genes that control the cell cycle, eventually leading to cancer.

Why can someone who did not inherit a retinoblastoma mutation still develop the disease?

Two functional copies of the Rb gene must both be lost for retinoblastoma to develop. In someone with two normal copies the chance that both are randomly mutated in the same cell is very low, so the disease rarely occurs. Someone who inherits one broken copy only needs one more mutation to lose all Rb function, making disease development much more likely and much earlier in life.

What is a consanguineous mating and why does it increase the risk of recessive disease in offspring?

A consanguineous mating is one between individuals who share a relatively recent common ancestor such as first cousins. Because they inherited DNA from the same ancestor they are more likely to both carry the same rare recessive allele. When two carriers mate there is a 25% chance their offspring will be homozygous recessive and show the disease. No new mutations are created