Chapter 11

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

growth factor

A signal transduction pathway activates a transcription factor that responds by __________.

initiating mRNA synthesis

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

In the presence of a regulatory protein the lac operon is _____.

not transcribed

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

oncogene

Enzyme complexes that break down protein are called _____.

proteasomes

Protein-phosphorylating enzymes' role in the regulation of gene expression involves _____.

protein activation

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

proto-oncogene

The nuclear membrane's role in the regulation of gene expression involves _____.

regulating the transport of mRNA to the cytoplasm

Which of these is NOT a component of the lac operon?

regulatory gene only

In eukaryotic cells, signal transduction pathways involve __________.

relay proteins that initiate transcription in the nucleus

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

spinal cord injuries

A mutation in the ras gene can __________.

stimulate cell division

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

A similar protein is found in both a bacterial cell and a single-celled eukaryote. However, the prokaryote seems to produce a much higher amount of the protein. A detailed investigation of the control mechanisms of this protein in both organisms would include a comparison of which of the following?

the mechanisms of transcriptional control

Regulatory proteins bind to _____.

the operator

A fruit fly's head-to-tail axis is established by __________.

the position of mRNA in the egg cell

Which of these is a regulatory gene?

D) Purple part

What is the function of a spliceosome?

RNA processing

What controls the way in which a zygote differentiates?

Selective genes are turned on and off, depending on the fate of the cell.

Which of these indicates an enhancer region?

A

Which of these directly bind(s) to the promoter?

C and D

Which of these is NOT a carcinogen? A) UV light B) cigarette smoke C) fat D) testosterone E) all of the above are carcinogens

E) all of the above are carcinogens

_____ is a carcinogen that promotes colon cancer.

Fat

The operon model of the regulation of gene expression in bacteria was proposed by _____.

Jacob and Monod

In fruit flies, there are molecules in the egg that determine the future head and tail ends of the animal. What occurs when mRNA from the head end of an embryo is injected into the tail end of an early embryo?

Some head structures develop at the tail end; the head end develops normally.

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? View Available Hint(s)

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

For the yeast Saccharomyces cerevisiae, cells of different mating types secrete factors that bind to specific receptor proteins on the cell surface of cells of the opposite mating type. This initiates a signal transduction pathway that eventually results in __________.

cell fusion

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

complementary mRNA sequences

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? A) Cloned animals possess chromatin structure identical to that of their parent animals. B) Cloned animals are physically identical when compared to their parents. C) The sheep Dolly is the only mammal that has been successfully cloned. D) Cloned animals often develop chronic conditions that are usually only associated with old age.

True: D) Cloned animals often develop chronic conditions that are usually only associated with old age.

Which of the following would be most likely to lead to cancer? A) Failure of both a proto-oncogene that promotes cell division and a tumor-suppressor gene to produce proteins. B) Failure of a proto-oncogene that promotes cell division to produce a protein and generation of multiple copies of a tumor-suppressor gene. C) Generation of multiple copies of a proto-oncogene that promotes cell division and activation of a tumor-suppressor gene. D) generation of multiple copies of a proto-oncogene that promotes cell division and inactivation of a tumor-suppressor gene.

True: D) generation of multiple copies of a proto-oncogene that promotes cell division and inactivation of a tumor-suppressor gene.

A mutation in the operator region of the trp operon can prevent the trp repressor from binding to this operator. When these mutant cells are placed in a solution containing chicken broth, which of the following events would happen?

Tryptophan would bind to the repressor.

Anhydrotic dysplasia is a genetic disorder in humans that results in the absence of sweat glands in the skin. Some men have this defect all over their bodies, but in women it is usually expressed in a peculiar way. Women with this disorder typically have small patches of skin with sweat glands and other patches without sweat glands. This pattern of sweat-gland distribution can be explained by __________.

X chromosome inactivation

_____ bind(s) to DNA enhancer regions.

activators

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

an entire plant can grow from a differentiated cell

Dioxin is a by-product of various industrial chemical processes. It is suspected of causing cancer and birth defects in both humans and other animals. Apparently, it acts by entering cells and binding to proteins, altering the pattern of gene expression. Therefore, it is reasonable to propose that dioxin acts by mimicking _____.

the role of transcription factors

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

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

tumor-suppressor gene