BIO 1012 Chapter 11

Since the first animal was produced using a fully differentiated cell, a number of observations have been made. Which of the following statements is true in regard to reproductive cloning?

Cloned animals often develop chronic conditions that are usually only associated with old age.

Which of the following statements best describes cancer cells?

Normal controls over cell division have been altered.

A proto-oncogene is a normal gene that can change into an oncogene. Oncogenes are potentially lethal genes that can cause cancer. Why do cells continue to maintain proto-oncogenes?

Proto-oncogenes are necessary for normal control of cell division.

A scientist is investigating a new drug that blocks the action of the enzyme responsible for splicing mRNA molecules. If this drug is effective, which of the following statements will be true?

RNA would remain in the nucleus as it would be unable to move through the nuclear pores, thus blocking translation of the gene.

The Rb protein prevents mitosis by inhibiting cells from entering S phase. Human papillomavirus (HPV) is thought to inhibit the action of the Rb protein in cervical epithelial cells. What would be the effect of cervical cells being infected with HPV?

The mitotic rate would increase.

Why do you think that adult stem cells are found in bone marrow and the lining of the small intestine specifically?

These cells must be able to regenerate various types of cells throughout life.

It is possible for a cell to make proteins that last for months; for example, hemoglobin in red blood cells. However, many proteins are short-lived and may be degraded in days or even hours. Why do cells make proteins with such a short life?

This enables cells to control the amount of protein present.

Alternative RNA splicing has revealed inaccuracies in the one gene-one polypeptide hypothesis. Why?

Transcription of the same gene can lead to the production of different mRNAs and therefore different proteins.

Proto-oncogenes have the potential to become oncogenes. Which of the following is most likely to lead to cancer?

a mutation that causes the proto-oncogene to become overactive

Cloning experiments with differentiated root cells from carrots revealed that __________.

an entire plant can grow from a differentiated cell

Using nuclear transplantation, it is possible to generate __________ for therapeutic uses.

blastocysts

Most human cancers are _____.

caused by the accumulation of mutations

MicroRNA (miRNA) functions by binding to __________ and blocking translation.

complementary mRNA sequences

Which of the following would be most likely to lead to cancer?

generation of multiple copies of a proto-oncogene that promotes cell division and inactivation of a tumor-suppressor gene

Colonoscopy is the examination of the large colon. It allows for visual diagnosis of ulcers and polyps, which may lead to colon cancer. A polyp _____.

is a cluster of abnormal cells

Experiments involving _____ have demonstrated that differentiated cells contain all of the genetic information found in undifferentiated cells.

nuclear transplantation

Stem cells could be immensely important in the treatment of which of the following conditions in the near future?

spinal cord injuries

After translation is complete, the insulin polypeptide is activated by __________.

the cutting of the initial translation product to yield two shorter chains joined together by sulfur linkages

In frogs, when the nucleus of an intestinal cell of a tadpole is transferred to an egg whose nucleus has been removed (nuclear transplantation), some of the eggs will develop into normal tadpoles. This demonstrates that _____.

these cells have retained all of their genetic potential

In humans, the agent responsible for the greatest number of cancers is _____.

tobacco

Exposure to which of the following substances increases cancer risk?

ultraviolet (UV) light exposure