PT: Chapter 16- Development, Stem Cells, and Cancer

The efficiency of cloning, and the ability to generate healthy cloned animals, has been largely hampered by the difficulty of __________. (Section 16.2) A. completely reversing epigenetic alterations in donor cell nuclei such as DNA methylation and chromatin packing B. implanting the clone into the surrogate mother C. transforming donor cells with genes encoding proteins required for normal embryonic development D. physically removing the nucleus from the egg cell that will ultimately receive the donor cell nucleus E. inducing recombination in differentiated donor cells in order to restore the full genomic complement

A. completely reversing epigenetic alterations in donor cell nuclei such as DNA methylation and chromatin packing right answer feedback:It is thought that the subtle abnormalities that often affect cloned animals result from an inability to completely reverse these alterations.

All are true regarding induced pluripotent stem (iPS) cells except _____.(Section 16.2) A. iPS cells have been demonstrated to function identically to embryonic stems cells B. iPS cells are formed by added genes to the genome of differentiated skin cells C. iPS cell technology could offer the potential to regenerate nonfunctional or diseased tissues and avoid the risk of transplant rejection in the diseased patient D. the reprogramming of diseased cells in humans to form iPS cells could provide model systems for studying the origins of the disease E. iPS cell technology may provide a more morally acceptable approach to therapeutic cloning

A. iPS cells have been demonstrated to function identically to embryonic stems cells right answer feedback:Earlier studies suggested that iPS stem cells could do everything that embryonic stems cells can do but later investigations showed that differences in gene expression and cell division exist between the two cell types.

Specific cells that appear undifferentiated under the microscope but are already fated to become muscle cells are called __________. (Section 16.1) A. myoblasts B. muscle fiber C. meristematic cells D. muscle cells E. bicoids

A. myoblasts right answer feedback:Under certain conditions precursor cells undergo changes in gene expression that commit them to becoming muscle cells. Once this differentiation has occurred, the cells are called myoblasts.

Nuclear transplantation involves __________. (Section 16.2) A. removing the nucleus of an egg cell and replacing it with the nucleus of a somatic cell B. placing the nucleus from an egg cell into an enucleated somatic cell C. inserting a sperm cell into an egg cell in vitro D. the use of microarray analysis and RNA interference E. the use of reverse transcriptase to make copies of the genes that are being expressed

A. removing the nucleus of an egg cell and replacing it with the nucleus of a somatic cell right answer feedback:In this way, the egg cell becomes diploid, similarly to when it is fertilized by a sperm.

__________ can give rise to any type of cell, whereas __________ can give rise to a subset of cell types. (Section 16.2) A. Totipotent cells ... nerve cells B. Embryonic stem cells ... adult stem cells C. Adult stem cells ... embryonic stem cells D. Adult stem cells ... totipotent cells E. Heterozygous cells ... homozygous cells

B. Embryonic stem cells ... adult stem cells right answer feedback:Embryonic stem cells are essentially totipotent and can differentiate into any type of cell. Adult stem cells are partially differentiated and can further differentiate into certain types of cells.

Dolly, the sheep, was cloned from an adult cell. She had a number of health problems and died at a relatively young age. Three mules that were born in 2003 were cloned from fetal cells. If it turns out that the mules remain healthy and live normal lives, how would this outcome tie in with Gurdon's observations with tadpoles? (Section 16.2) A. Gurdon found that nuclei from older donor cells were more likely to correctly direct differentiation and give rise to healthy tadpoles. B. Gurdon found that the ability of a transplanted nucleus to direct normal development was inversely related to the age of the donor. C. Gurdon found a positive correlation between the age of the donor nuclei and the ability of the nuclei to direct differentiation. D. Gurdon found no correlation between the age of the donor cells and the ability of the transplanted nucleus to direct development. E. None of the listed responses is correct.

B. Gurdon found that the ability of a transplanted nucleus to direct normal development was inversely related to the age of the donor. right answer feedback:In animals it appears that the age of the donor may have an effect on the ability of the nucleus to properly direct gene expression during development. Cloning has not been going on long enough for us to have a large enough data set to draw solid conclusions.

Instead of developing a head and a tail, an abnormal Drosophila embryo develops two tails. This is most likely due to __________. (Section 16.1) A. apoptosis B. a mutation in a maternal effect gene C. destruction of the RNA polymerase molecules responsible for the transcription of genes that encode head-related proteins D. a failure involving post-transcriptional modification of mRNA E. a mutation in an operon

B. a mutation in a maternal effect gene right answer feedback:Some maternal effect genes provide positional information in the developing embryo. Mutations in these genes can cause abnormal development.

Most human cancers are __________. (Section 16.3) A. caused by viruses B. caused by the accumulation of somatic mutations C. inherited from both parents, like an autosomal recessive allele D. caused by radiation E. inherited from one parent, like an autosomal dominant allele

B. caused by the accumulation of somatic mutations right answer feedback:Most human cancers result from the accumulation of multiple mutations in a single somatic cell that then loses control over its rate of growth and cell division.

MyoD promotes muscle cell development by __________. (Section 16.1) A. increasing the translation of muscle-related genes B. turning on the expression of multiple muscle-related genes C. stimulating the production of muscle-specific splicing variants of certain mRNAs D. stimulating a receptor on the surface of muscle cells, thus activating a signal-transduction pathway that promotes muscle development E. enhancing apoptosis of non-muscle cells

B. turning on the expression of multiple muscle-related genes right answer feedback:MyoD is a protein that acts as a transcription factor to turn on many genes involved in muscle cell development, including the gene that codes for MyoD.

A cancer cell __________. (Section 16.3) A. requires less nutrients than a normal cell B. usually does not contain a nucleus C. does not respond to the chemical signals that control cell division D. is typically more than 10 times larger than a normal cell E. All of the choices are correct.

C. does not respond to the chemical signals that control cell division right answer feedback:Cancer is a set of diseases in which cells escape from the control mechanisms that normally limit their rate of division.

During the process of differentiation, cells __________. (Section 16.2) A. exchange DNA with other cells via the process of horizontal gene transfer B. lose genes C. express different genes in response to cell signaling D. gain and lose genes, depending on what type of cell they will become E. randomly turn on and off genes until the right combination is reached

C. express different genes in response to cell signaling right answer feedback:Although the DNA in every cell is the same, different genes are expressed in a muscle cell and a nerve cell.

Cell differentiation is first observable when __________. (Section 16.1) A. apoptosis occurs B. patterns of mitosis change in different cells C. mRNAs for tissue-specific proteins appear in a cell D. the genome of a particular cell changes E. a cell appears different under the microscope

C. mRNAs for tissue-specific proteins appear in a cell right answer feedback:Even before a cell's structure begins to change, differentiation is heralded by the appearance of these mRNAs in the cell.

The BRCA1 and BRCA2 genes are thought to be what type of genes? (Section 16.3) A. transcription factor genes B. proto-oncogenes C. tumor-suppressor genes D. viral genes E. oncogenes

C. tumor-suppressor genes right answer feedback:They are thought to be tumor-suppressor genes because the wild-type alleles protect against breast cancer.

Which accurately characterizes our current understanding of cancer development? (Section 16.3) A. Study results suggest that mutations in genes that are transcribed into ncRNA do not likely contribute to cancer development. B. Although the role of p53 in cancer development is fully understood, it is not clear how its interaction with ncRNA can lead to the onset of tumor formation. C. Mutations in a single gene cannot significantly increase susceptibility to cancer. D. In order for a cell to become fully cancerous, it typically must have at least one active oncogene and the mutation or loss of several tumor-suppressor genes. E. Nearly all cancers are caused by the multistep accumulation of mutations over the life-span of the individual.

D. In order for a cell to become fully cancerous, it typically must have at least one active oncogene and the mutation or loss of several tumor-suppressor genes. right answer feedback:Our current understanding suggests that several key changes must occur in the DNA of a cell before it can become cancerous. These changes are brought about by mutations to convert a proto-oncogene to an active oncogene and the loss of tumor-suppressing proteins such as p53.

In what way can cancer be hereditary? (Section 16.3) A. A person can inherit cancer cells from one of his/her parents. B. All of the mutations necessary for full cancer development can be inherited, giving a person a predisposition to developing cancer. C. Tumor-suppressor genes can be inherited, giving the person a predisposition to developing cancer. D. One or two of several mutations necessary for full cancer development can be inherited, giving a person a predisposition to developing cancer. E. Proto-oncogenes can be inherited, giving the person a predisposition to developing cancer.

D. One or two of several mutations necessary for full cancer development can be inherited, giving a person a predisposition to developing cancer. right answer feedback:Because most cancers involve several mutations, a person who inherits one or more of these mutations will be more susceptible to cancer, but will not necessarily develop it. Epigenetics also plays a role here.

Cells can influence each other's development by a process known as __________. (Section 16.1) A. cleavage B. apoptosis C. chimeras D. induction E. fating

D. induction right answer feedback:Induction occurs when cell signals from one cell affect the development of nearby cells.

What two genes are often mutated in colon cancer? (Section 16.3) A. ras and myoD B. p21 and p53 C. APC and myoD D. ras and p53 E. BRCA1 and BRCA2

D. ras and p53 right answer feedback:ras, an oncogene, and p53, a tumor-suppressor gene, are often found to be mutated in colon cancers.

In the human genome, oncogenes __________. (Section 16.3) A. enhance DNA repair B. slow cell division C. promote cell adhesion D. stimulate cell division E. suppress tumors

D. stimulate cell division

What gene has been called the "guardian angel of the genome?" (Section 16.3) A. the p21 gene B. the myoD gene C. the BRCA1 gene D. the p53 gene E. the ras gene

D. the p53 gene right answer feedback:The p53 gene can activate several genes involved in DNA repair, halting of the cell cycle, or initiation of apoptosis.

"Therapeutic cloning" refers to __________. (Section 16.2) A. treating patients with therapeutic proteins made using recombinant DNA technology B. cloning animals to obtain organs that could be used for transplantation into humans C. treating a genetic disease by obtaining cells from an individual with the disease, introducing genes into the cells in order to repair the genetic defect, and then reintroducing the cells back into the individual D. the use of cloned embryos as a source of stem cells to treat disease E. All of the choices are correct.

D. the use of cloned embryos as a source of stem cells to treat disease right answer feedback:It has been proposed that these cells can be used to treat diseases such as Parkinson's disease, Huntington's disease, and diabetes. However, aside from ethical and moral problems, embryonic stem cells tend to run riot and cause serious problems when used in this way.

Why is cancer more prevalent in older people? (Section 16.3) A. Cancer lies dormant for many years before causing problems. B. Cancer is caused by viruses, and older people are more susceptible to viral infections. C. Cancer involves changes in gene expression, and it takes many years for gene expression to change. D. Most cancers are inherited as a recessive allele, so it takes time for the allele to be expressed. E. Cancer involves an accumulation of mutations, and older people have had more time to accumulate mutations in their DNA.

E. Cancer involves an accumulation of mutations, and older people have had more time to accumulate mutations in their DNA. right answer feedback:Epigenetics plays a factor here. Older people have simply had more cell divisions, more exposure to environmental carcinogens, and so on. Chance dictates that they have had more opportunities for mutations to occur.

Cytoplasmic determinants __________. (Section 16.1) A. are carried to the ovum by the sperm B. are coded for by embryonic genes C. act by binding to a plasma protein receptor that then initiates a signal-transduction pathway D. are coded for by paternal genes E. are influenced by maternal substances in the egg that influence the course of early development

E. are influenced by maternal substances in the egg that influence the course of early development right answer feedback:Cytoplasmic determinants are present in egg cells before fertilization. Mutations in the mother's genes can lead to defects such as a fly embryo having two heads.