Question

Define the "two-hit hypothesis" for retinoblastoma. Drag the terms on the left to the appropriate blanks on the right to complete the sentences. Not all terms will be used. ResetHelp both copies sporadic retinoblastoma only one copy hereditary retinoblastoma of one gene must be mutated in order for retinoblastoma to develop. This hypothesis was based on the finding that always affected both eyes, whereas only affected one eye.

Answer 1

Retinoblastoma is caused by a series of mutations in the Rb gene of retinoblastoma. Sporadic retinoblastoma is characterized by the appearance of a tumor in only one eye. People with this type of mutation are born with normal copies of the Rb1 gene, but because of the mutation, both copies of the gene mutate. These types of mutations are not inherited, they are produced by occasional circumstances after birth occurs. If the mutation is hereditary, a mutant copy is inherited from the parent. A second mutation is needed, which may happen later for retinoblastoma to occur.

Step-by-step explanation:

Answer 2

This hypothesis was based on the finding that hereditary retinoblastoma always affected both eyes, whereas sporadic retinoblastoma only affected one eye. Both copies must be mutated in order for retinoblastoma to develop in hereditary retinoblastoma and sporadic retinoblastoma.

Step-by-step explanation:

The two hit hypothesis states that both genes must be mutated to have retinoblastoma, these two hits can happen in 2 ways:

1. Hereditary retinoblastoma: a person inherits one mutated gene, and later in life, the other copy of the gene is also mutated, causing retinoblastoma.
2. Sporadic retinoblastoma: a person is born with two healthy copies of the gene, but at some stage in life, one of these copies is affected, and later on the other, causing retinoblastoma.