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Answer

In __________ organisms, the primary function of a gene in a cell is to participate in regulating the body as a whole and not to responding to the cell's immediate environment.

multicellular

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The maintenance of a constant environment in a cell is called ___________.

homeostasis

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. A bacterial cell takes advantage of changing __________ conditions through control of gene expression.

environmental

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. In multicellular organisms, gene _________ is critical for directing development and maintaining homeostasis.

regulation

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Eukaryotic cell mRNA transcripts tend to be very ______ and can remain in the cell for hours.

stable

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Transcriptional control-proteins increase the rate of transcription by binding to

enhancer sequences within the DNA.

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All regulatory proteins have common DNA binding motifs, which are particular bends in their protein chains that permit them to interlock with the

major groove of the DNA helix.

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9. Vertebrate cells apparently possess a protein that by binding to clusters of 5-methylcytosine ensures that the bound gene will stay in the "off" position. This control on the role of gene regulation is a result of

methylation.

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10. Regulatory proteins shut off transcription by binding to a site immediately in front of the promoter and often even overlapping the promotor. This site is referred to as the

operator site.

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11. Histones are tightly packed into ______, which are located within the DNA

nucleosomes

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12. Which of the following is the hallmark of multicellular organisms

homeostasis

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13. Enhancers are the binding sites for the

specific transcription factors.

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14. The most common form of control of gene expression in both the prokaryotic and eukaryotic organisms is

transcriptional control.

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15. A nucleosome contains ____ histones within its core

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16. The basic tool of genetic regulation is the ability of certain proteins to bind to specific

regulatory DNA sequences.

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17. DNA methylation, adding a methyl group to DNA nucleotides, in vertebrates ensures that

once a gene is turned off, it will remain off.

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18. Which of the following is not true about control of gene expression?

In bacteria it allows them to replicate without control.

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19. RNA polymerase binds to a site on DNA called the

promoter.

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20. Small RNAs, once thought to be of no importance in gene expression contain

between 21 to 28 nucleotides.

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21. Although the specific mechanism of RNA interference has not been fully defined, it involves

double stranded RNA interference with mRNA.

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22. Proteins that bind to regulatory sequences have shapes that fit into the

major groove of DNA.

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23. The DNA-binding proteins of almost all regulatory proteins employ one of a small set of shapes that enable them to fit into the major groove of DNA. These shapes are called

structural motifs.

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24. All of the following are examples of shapes in regulatory proteins which are used to bind to DNA except the

TATA box.

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25. In gene regulation, negative control is exerted by a(n)

repressor.

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26. In gene regulation, a gene is "turned on" by a(n)

activator.

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27. A bacterial gene regulatory system is likely to have all of the following except

one or more introns.

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28. Small RNAs can regulate gene expression. One type, called micro RNA (miRNA), acts by binding directly to

mRNA to prevent translation.

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29. The lac regulatory system is important to bacteria because the sugar lactose

is only rarely available; producing enzymes all the time is costly.

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30. A well-understood transcriptional activator of E. coli, which initiates the transcription of genes in nonglucose environments, is called

catabolite activator protein (CAP).

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31. In eukaryotes, specific transcription factors have two distinct domains:

a DNA-binding domain and an activation domain.

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32. Which of the following must happen for transcription to be initiated?

RNA polymerase must have access to the DNA double helix and also must be capable of binding to the gene's promoter.

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33. Certain proteins can bind to specific DNA regulatory sequences by

entering the major groove of the DNA and reading the nucleotide base pairs.

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34. Regulatory proteins can identify specific sequences on the DNA double helix without unwinding the helix. This is accomplished by

inserting DNA-binding motifs into the major groove of the double helix where the edges of the nitrogen bases protrude.

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35. When E. coli cells produce the amino acid tryptophan, a cluster of five genes is transcribed together. This cluster of genes is referred to as the

trp operon.

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36. The proteins necessary for the use of lactose in E. coli are collectively called the

lac operon.

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37. Eukaryotic organisms

have their transcription occurring in the nucleus and translation in the cytoplasm.

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38. The CAP molecule can attach to the CAP binding site only when the

CAP molecule is bound to cAMP.

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39. Which of the following statements regarding primary transcripts in eukaryotes is correct?

The primary transcript is a faithful copy of the entire gene including exons and introns.

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40. One of the DNA-binding motifs that contains a nearly identical sequence of 60 amino acids in many eukaryotic organisms is known as the

homeodomain.

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41. The most common DNA-binding motif is the

helix-turn-helix.

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42. A protein that regulates transcription by binding to the operator.

repressor

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43. A protein that initiates the transcription of genes which allow the use of non-glucose molecules.

CAP

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44. A cluster of functionally-related genes encoded into a mRNA molecule; a mode of prokaryotic gene regulating unit.

operon

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45. A site of negative genetic regulation; binding by repressor blocks transcription.

operator

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46. A site at the 5' end of a gene to which RNA polymerase attaches to initiate transcription.

promoter

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47. You are performing a mutagenesis screen to isolate mutations in Drosophila. While looking through a batch of mutagenized flies, you find a fly in which its antenna had been transformed to a pair of extra legs. You surmise that this fly must have a mut

homeodomain

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48. The enzyme β-galactosidase acts on lactose to form galactose. In turn, the presence of galactose leads to expression of the enzymes responsible for the metabolism of galactose. In this case, lactose is serving a carbon source and as a(n)

inducer.

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49. The lactose analog isopropyl-β-D-thio-galactoside (IPTG) is often used to regulate gene expression systems in bacteria. IPTG does not act as a substrate for β-galactosidase, but can bind to, and inactivate, repressor. In this case, IPTG serves as a(n)

inducer.

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50. The main form of glucose repression of the lac operon is

inducer exclusion.

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51. Which of the following statements regarding control of the lac operon and lactose utilization in bacteria is false?

Bacteria preferentially utilize lactose as a carbon source.

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52. Mutations in the -35 region of the trp operon would

interfere with RNA polymerase binding to the promotor.

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53. You are studying the regulation of a prokaryotic operon. Experimental results suggest that the operon is governed by negative control. Based on this information, you conclude that

the operon is OFF in the absence of its regulatory protein.

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54. In eukaryotes, the binding of TFIID is followed by the binding of a number of other general transcription factors. Which of the following lists the correct order of binding of these factors?

TFIIE, TFIIF, TFIIA, TFIIB, TFIIH

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55. Your research project involves the characterization of a recently identified transcription factor. As part of your project, you want to determine if this transcription factor binds directly to any of the general transcription factors. Unfortunately, h

Since transcription domains can be separated, try to express and purify only the activation domain.

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56. You are working to identify enhancer regions of a particular gene. You should look

primarily upstream of the promoter; distance from the promoter does not matter.

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57. The progesterone receptor (PR) is a steroid hormone receptor and transcription factor. The protein SRC-1, which does not bind DNA by itself, can bind to PR and increase expression of genes regulated by PR. Based on this information, SRC-1 is a(n)

coactivator.

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58. The TFIID complex is formed by

TATA-binding protein TBP and TAFs.

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59. Which of the following statements regarding the eukaryotic transcription initiation complex is false?

Basal factors remain associated with RNA pol II after positioning RNA pol II at the start site.

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60. The p300/CBP (CREB-binding protein) coactivator proteins are histone acetyltransferases that help regulate the transcription of many genes. Based on this information, these proteins are involved in

chromatin remodeling.

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61. DNA methylation is the only known natural modification of DNA. It affects

cytosine bases.

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62. If you were able to look very closely at a portion of DNA and find methylated histones, you would

be looking at a region of inactive chromatin.

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63. Elucidation of the histone code might

allow us to turn specific genes on or off.

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64. You are studying the function of a recently identified gene in C. elegans. You have been performing genetic screens for several months in an attempt to isolate loss-of-function mutations in this gene, but unfortunately you have been unsuccessful. Your

Use RNA interference to prevent mRNA translation.

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65. The enzyme dicer chops dsRNA molecules into small pieces of

miRNA and siRNA.

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66. The gene encoding apolipoprotein B exists in two isoforms, APOB100 and APOB48. These two forms are produced as a result of

RNA editing.

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67. Production of the iron-storing protein ferritin is regulated by aconitase, which binds to a 30-nucleotide sequence at the beginning of the ferritin mRNA and interferes with ribosome binding. Aconitase is a

translation repressor protein.

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68. Which of the following statements regarding the ubiquitin-proteosome pathway is false?

Ubiquitination of a targeted protein requires only one molecule of ATP.

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69. What is the difference between a gene that is derepressed and one that is induced?

A gene that is derepressed is turned on because a repressor molecule is absent. By comparison, a gene that is induced is turned on because an inducer molecule is present.

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