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Unit 14, Bio156


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The term gene expression refers to the:
process by which genetic information flows from genes to proteins
The cells that make up the various tissues of an animal are so different because:
only certain genes in each cell type are expressed
The lac operon is found:
in E. coli
The lac operon:
both A and B are correct
A. prevents lactose-utilizing enzymes from being expressed when lactose is absent from the environment
B. coordinates the production of lactose-utilizing enzymes when lactose is present in the environment
RNA polymerase binds to which of the following?
the promoter
In the lac operon, a regulatory gene outside of the operon is always producing ___, which (in the absence of lactose) binds to the ___.
a repressor, operator
The lac operon is ___ when the repressor is bound to lactose.
Specialization in the structure and function of cells that occurs during the development of a multicellular organism is called:
cellular differentiation
The basis of cellular differentiation is:
selective gene expression
The production of an organism that is genetically identical to another organism is called:
The result of cloning is an offspring who is always genetically identical to the organism that supplied:
the nucleus
Cells from a differentiated part of a plant can be removed, placed into nutrient medium, and the cells may grow into a complete plant. This shows that:
differentiation does not involve irreversible changes in DNA
Which of the following types of cells has the greatest potential for differentiation?
embryonic stem cells
If the DNA in a human cell was stretched out straight, how long would it be?
3 meters long
In the eukaryotic nucleus, the unit that consists of DNA wound around a core of eight histone proteins is called a:
Dense packing of DNA in chromosomes:
prevents gene expression
X-chromosome inactivation
can lead to a tortoiseshell pattern in cats
In eukaryotic cells, enhancers and activators regulate:
In eukaryotic cells, transcription factors can bind to:
all of the above
A. enhancers
B. the promoter
C. RNA polymerase
Regions of noncoding DNA within a gene are called:
The coding regions of a gene (the portions that are expressed as polypeptide sequences) are called:
RNA splicing involves the:
removal of introns from the molecule
Which of the following is an explanation of why a single gene may code for more than one polypeptide?
alternative RNA splicing
After a polypeptide is produced, it may need further processing before it becomes an active protein. This activation of the protein in a eukaryotic cell:
occurs in the cytoplasm
Which of the following is a eukaryotic mechanism that regulates the amount of the active protein in a cell?
all of the above
A. breakdown of mRNA
B. regulation of translation initiation
C. activation of the protein
D. breakdown of the protein
In egg development or early embryonic development of animals, proteins are carried back and forth between cells to help guide development. This is called:
cell-to-cell signaling
A master control gene that regulates many other genes, and determines the identity of a body structure of a developing organism is called:
a homeotic gene
A signal molecule from one cell will bind to:
a receptor protein in the membrane of the target cell
A signal molecule from one cell can activate transcription factors in a target cell by:
triggering a signal-transduction pathway
Developmental similarities observed in most vertebrates are probably due to:
nucleotide sequences called homeoboxes that have changed very little over time
Homeoboxes of very similar sequences are found in:
virtually all eukaryotic organisms
Homeoboxes function as control mechanisms by:
switching homeotic genes on and off
Why can organisms be so different, yet still have very similar homeoboxes?
Homeoboxes simply function as switches to turn homeotic genes on and off. Homeotic genes can still vary considerable among different organisms.
A gene that causes cancer is called a:
A normal gene with the potential to become an oncogene is called a:
The normal role of most proto-oncogenes is to:
regulate the cell cycle
The role of a tumor-suppressor gene it to:
inhibit cell division and uncontrolled cell growth
A mutant tumor-suppressor gene:
produces a defective protein unable to function in a pathway that normally inhibits cell division
Many cancers, such as colon cancer, can take a long time to develop because:
it does not arise until several mutations have accumulated
Why is cancer always a "genetic disease?"
it is always the consequence of changes in DNA
Why are most breast cancer cases considered to be "nonhereditary?"
most breast cancers are due to somatic cell mutations, not inherited mutations
The carcinogen known to cause the most cases of cancer is:

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