Chapter 11

In 2013, an estimated 160,000 people in the United States will die of lung cancer. If the cancer death rate is expected to increase by 1% per decade, approximately how many people will die of lung cancer in the United States in 2033?

163,000

During an experiment assessing the development of a fly embryo, a scientist artificially turns on a homeotic gene that controls eye development in somatic cells that develop into the wings.

A mutant adult fly will develop that has eyes on its wings

A single cell, the zygote, can develop into an entirely new organism with many different specialized cells. Which of the following statements about this process is false?

Additional genetic information for the formation of specialized cells is passed on to the developing embryo via the mother.

Which of the following statements regarding stem cells is false?

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

Which of the following processes occurs when a salamander regenerates a lost limb?

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

Which of the following statements regarding DNA packing is false?

DNA packing tends to promote gene expression.

All of the following mechanisms are used to regulate protein production except

DNA replication

Enhancers are

DNA sequences to which activator proteins bind.

What is the proper order of events in the expression of a eukaryotic protein?

DNA unpacking, mRNA splicing, translation, protein folding

Transcription factors attach to

DNA.

Which of the following statements about proto-oncogenes is false?

If a proto-oncogene's gene product is produced in smaller quantities, a cell may become cancerous.

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

There is a mutation in the operator of the lac operon in a cell such that the lac repressor always stays bound to the operator. If lactose is added to the cell, what will happen?

Lactose will bind to the repressor, and lac enzymes will not be produced

Which of the following statements about microarrays is false?

Microarrays use tiny portions of double-stranded RNA fragments from a large number of genes.

Which of the following statements regarding cancer risk factors is false?

Mutagens are usually not carcinogens

A normal muscle cell produces the myosin protein, which allows muscles to contract. You discover a single muscle cell that has tRNAs that do not bind to amino acids. Will the myosin gene be expressed in this muscle cell? Why or why not?

No, because if the tRNAs do not bind amino acids, then translation cannot occur.

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 of the following statements regarding skin cells and muscle cells in your body is true?

Skin cells and muscle cells each contain information about both muscle proteins and skin color.

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

A stomach cell is producing pepsin, an enzyme that hydrolyzes proteins. Which of the following events suggests that gene expression of pepsin has been turned off in the cell?

The chromosome with the pepsin gene is tightly coiled.

Which of the following statements about fruit fly development is false?

The location of the head and tail ends of the egg is primarily determined by the location of sperm entry during fertilization.

Which of the following is likely to occur in E. coli cells that are grown in skim milk?

The trp repressor is activated, and the cells will produce lactose-utilizing enzymes

Two yeast cells, one of type a and the other type α, are in proximity to each other. The a yeast cell has a mutation in the gene for the α factor receptor protein such that the receptor does not translocate to the surface of the a cell. If both cells secrete their respective a and α factors, which of the following outcomes is most likely to occur?

The α cell will grow toward the a cell

There is a mutation in a promoter next to a gene such that RNA polymerase can never bind. What steps must occur for the gene to be transcribed?

Transcription will never take place in this specific example

There is a mutation in the operator of the trp operon in a cell such that the trp repressor is unable to bind to the operator. If tryptophan is added to the cell, what will happen?

Tryptophan will bind to the repressor, and trp enzymes will be produced

E. coli can synthesize the amino acid threonine or absorb it from the environment. In the thr operon, the repressor is active when it is bound to threonine. If an E. coli bacterium is in an environment where threonine is absent, will transcription of threonine synthesis genes take place? Why or why not?

Yes, because threonine will not be bound to the repressor, so the repressor will be inactive

In plants, most differentiated cells retain

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

Scientists are attempting to make a chicken look like a dinosaur ("dino-chicken") by using drugs or proteins to turn on certain homeotic genes during the development of a chicken embryo. If the scientists are successful in creating both male and female "dino-chickens," and then the "dino-chickens" mate together, what type of offspring would the two "dino-chickens" have?

a male or female normal chicken

The expression of the tryptophan operon is controlled by

a repressor that is active when it binds to tryptophan.

Proteins that bind to DNA and turn on operons by making it easier for RNA polymerase to bind to a promoter are called

activators.

The lac operon of E. coli is ________ when the repressor is bound to lactose.

active

Which of the following permits a single gene to code for more than one polypeptide?

alternative RNA splicing

In a prokaryote, a group of genes with related functions, along with their associated control sequences, defines

an operon.

The genes for the enzymes of glycolysis

are active in all metabolizing cells, but the genes for specialized proteins are expressed only in particular cell types.

Signal transduction pathways

are mechanisms of communication that probably evolved in ancient prokaryotes

Adult stem cells have limited therapeutic potential

because their developmental potential is limited to certain tissues

In female mammals, the inactive X chromosome in each cell

becomes a Barr body.

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.

In multicellular organisms, the coordination of cellular activities relies on

cell-to-cell signaling and signal transduction pathways

RNA interference (RNAi) can be used by

cells to prevent infections from double-stranded RNA viruses

The cloning of Dolly the sheep

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

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

disrupt normal regulation of the cell cycle.

The coding regions of a gene are called

exons.

In thinking about 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

Which of the following mammals has not yet been cloned and brought through the complete gestation cycle?

human

Small pieces of RNA that can regulate translation of mRNA are called

microRNA.

What is the correct order of structures in a chromosome from smallest to largest?

nucleotide, histone, nucleosome, tight helical fiber, supercoil, chromosome

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

oncogene.

To initiate a signal transduction pathway, a signal binds to a receptor protein usually located in the

plasma membrane

The lac operon in Escherichia coli

prevents lactose-utilizing enzymes from being expressed when lactose is absent from the environment.

The term "gene expression" refers to the

process by which genetic information flows from genes to proteins.

In terms of gene regulation, what do eukaryotes and prokaryotes have in common?

promoters that bind RNA polymerases

Both prokaryotic and eukaryotic cells use ________ to turn certain genes on or off.

proteins

RNA splicing involves the

removal of introns from the molecule

Which of the following molecules are not required to express a gene in eukaryotic cells?

repressor protein

The tortoiseshell pattern on a cat

results from X chromosome inactivation.

The basis of cellular differentiation is

selective gene expression.

A homeotic gene

serves as a master control gene that functions during embryonic development by controlling the developmental fate of groups of cells.

Cancer of the colon is caused by

several somatic cell gene mutations

A signal outside a cell triggers changes in the transcription and translation inside the cell through

signal transduction pathways

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

the production of more effective tumor-suppressor gene products

Which of the following possible uses 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.

The relationship between DNA and chromosomes is most like

thread wrapped around a spool.

Yeast are able to communicate with each other

through chemical signaling

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

tobacco

A gene operon consists of

transcribed genes, an operator, and a promoter

Which of the following mechanisms of controlling gene expression occurs outside of the nucleus?

translation

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