Mastering biology ch 11
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
In eukaryotic cells, signal transduction pathways involve __________.
a series of relay molecules, of which the last activates a transcription factor
_____ 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
In the presence of a regulatory protein the lac operon is _____.
not transcribed
Enzyme complexes that break down protein are called _____.
proteasomes
Protein-phosphorylating enzymes' role in the regulation of gene expression involves _____.
protein activation
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
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
Which of these indicates an enhancer region?
A
Which of these directly bind(s) to the promoter?
C and D
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 these is a regulatory gene?
D
The operon model of the regulation of gene expression in bacteria was proposed by _____.
Jacob and Monod
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.
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?
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
_____ is a carcinogen that promotes colon cancer.
fat
Which of these is NOT a carcinogen?
fat testosterone cigarette smoke UV light all of the above are carcinogens
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
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
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
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
