Biology test

Mutations in the proto-oncogene ras and the tumor-suppressor gene p53

disrupt normal regulation of the cell cycle.

_____ is a carcinogen that promotes colon cancer.

fat

Considering their role in cell division, oncogenes are like the ________ of a car, while tumor-suppressor genes are like the ________ of a car.

gas pedal; brakes

A(n) ____________is a protein that promotes cell division. In excess, such a protein may lead to cancer

growth factor

Which mammal has not yet been cloned and brought through the complete gestation cycle?

human

A normal gene that, if mutated, can lead to cancer is called a(n) __________

proto-oncogene

The carcinogen known to cause the most cases and types of cancer is

tabacco

Which process occurs when a salamander regenerates a lost limb?

Certain cells in the limb dedifferentiate, divide, and then redifferentiate to form a new limb.

Why can some plants be cloned from a single cell?

Plant cells can dedifferentiate and give rise to all of the specialized cells required to produce an entire plant.

Which is not a factor that contributes to normal cells becoming cancerous?

the production of more effective tumor-suppressor gene products

Which possible use of reproductive cloning is still considered by most to be an unresolved ethical issue?

the reproductive cloning of humans

The use of cloning to produce special embryonic stem cells is called

therapeutic cloning

A(n) ____________ is a gene that encodes proteins that inhibit cell division. Such proteins normally help prevent cells from becoming cancerous.

tumor-suppressor gene

The development of colon cancer occurs slowly, and colon cancer is more frequently seen in the elderly than the young. This is most likely because

usually six or more somatic mutations must occur to give rise to the cancer, which takes time.

A gene that causes a cell to become cancerous is called a(n) __________

oncogene

A gene that can cause cancer when present in a single copy in a cell is called a(n)

oncogene.

Which statement regarding stem cells is false?

Adult, but not embryonic, stem cells can be grown in laboratory culture.

Melanoma (skin cancer) can develop after several mutations occur in skin cells. If a woman is diagnosed with melanoma and becomes pregnant, what are the chances that her offspring will inherit melanoma?

It is unlikely that the offspring will be born with melanoma.

Which statement regarding cancer risk factors is false?

Mutagens are usually not carcinogens.

A cell is expressing the mutant form of ras, but one of the downstream relay proteins is not present because of another mutation. How will cell division be affected in this scenario?

The cell will not divide at all unless other proteins that stimulate cell division are present.

A cell has a mutation in both alleles of its p53 gene that causes the p53 protein to be three times as effective as normal. What do you predict would happen to this cell?

The cell would divide normally or possibly not at all.

What are 4 carcinogens?

UV light, cigarette smoke, testosterone, fat

In plants, most differentiated cells retain

a complete set of their genes and retain the ability to express those genes under certain circumstances

Adult stem cells have limited therapeutic potential

because their developmental potential is limited to certain tissues.

Mutations in the p53 gene can lead to cancer by

causing the production of a faulty protein that is no longer able to inhibit cell division.

The figure below shows a normal cell transduction pathway. If the receptor weren't there, the most likely outcome would be

cell division will be increased.

The cloning of Dolly the sheep

demonstrated that the nuclei from differentiated mammalian cells can retain their full genetic potential.