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| 1 | |
An operon consists of which three components? |
| | A) | a repressor, an operator, and an enzyme |
| | B) | a repressor, a promoter, and an operator |
| | C) | a regulatory gene, a repressor, and a promoter |
| | D) | a regulatory gene, a promoter, and an operator |
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| 2 | |
Consider the lac operon. What happens when the repressor is active? Inactive? |
| | A) | it binds to the operator and turns the gene that produces lactose enzymes off; it is bound by lactose and the gene for lactose enzymes is turned on |
| | B) | it is bound by lactose and the gene for lactose enzymes is turned on; it binds to the operator and turns the gene that produces lactose enzymes off |
| | C) | it is bound by lactose enzymes and the gene for these enzymes is amplified; it is bound by lactose and the gene for lactose enzymes is turned off |
| | D) | it is bound by lactose and the gene for lactose enzymes is turned off; it is bound by lactose enzymes and the gene for these enzymes is turned on |
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| 3 | |
Several DNA-binding proteins serve to turn genes on in eukaryotes. For instance, __________ assist RNA polymerase in binding the promoter of an operon and __________ bind(s) enhancers, which can physically bend DNA to create a loop such that transcription activators can bind transcription factors. |
| | A) | enhancers; histones |
| | B) | histones; RNA polymerase |
| | C) | transcription activators; transcription factors |
| | D) | transcription factors; transcription activators |
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| 4 | |
Chromatin that is wound around a core of eight histones is called __________. Areas of highly condensed chromatin are called __________. |
| | A) | euchromatin and it is not transcribed; heterochromatin and are transcribed |
| | B) | heterochromatic and it is transcribed; euchromatin and are not transcribed |
| | C) | euchromatin and it is transcribed; heterochromatin and are not transcribed |
| | D) | heterochromatin and it is not transcribed; euchromatin and are transcribed |
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| 5 | |
What purpose does a chromatin-remodeling complex serve in transcription? |
| | A) | The chromatin-remodeling complex changes heterochromatin into euchromatin. |
| | B) | The chromatin-remodeling complex reassembles the unwound euchromatin following transcription. |
| | C) | The chromatin-remodeling complex moves the histone portion of a nucleosome so that DNA is accessible for transcription. |
| | D) | The chromatin-remodeling complex changes euchromatin into heterochromatin. |
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| 6 | |
Hox genes are master developmental regulatory genes because they code for Hox proteins which are |
| | A) | in control of the basic coordinates and segmentation of the body. |
| | B) | responsible for eye development in many different types of organisms. |
| | C) | transcription activators that bind enhancers. |
| | D) | essential DNA-binding proteins, transcription factors, that bind to and activate other regulatory genes. |
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| 7 | |
Which choice is NOT an example or result of alternative mRNA splicing, which influences gene expression? |
| | A) | All of the exons are excised from the RNA, leaving only the introns. |
| | B) | When introns are excised from the RNA, some exons are also removed. |
| | C) | Some of the introns are not removed during splicing. |
| | D) | The mRNA sequence is altered, and thus so is the corresponding protein product. |
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| 8 | |
Small RNAs regulate the amount of a gene’s product in a few ways. Which of the following is NOT one of these ways? |
| | A) | Small RNAs can become siRNAs, which join with an enzyme to form an RNA induced silencing complex that targets mRNAs for breakdown. |
| | B) | Small RNAs are the precursors to miRNAs, which can bind to an mRNA in the cytoplasm and lessen its translation. |
| | C) | Small RNAs can make some genes inaccessible for transcription by altering the compaction of euchromatin. |
| | D) | Small RNAs can become dsRNA, which is copied in place of DNA to produce unusable mRNA transcripts. |
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| 9 | |
If a mechanism for controlling gene expression is in the cytoplasm, it most likely influences which of the following processes? |
| | A) | transcription |
| | B) | translation |
| | C) | transcription and translation |
| | D) | DNA replication |
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| 10 | |
Control of gene expression in the cytoplasm, specifically translational control, occurs when processed mRNA reaches the cytoplasm and before there is a protein product. How is translation controlled? |
| | A) | This control can be exerted by miRNAs or translation repressor protein(s). |
| | B) | These mechanisms for control include the degradation of mRNA without its poly-A tail. |
| | C) | All of these choices are correct. |
| | D) | This control can be exerted by changes in the availability of mRNA for translation at the ribosome. |
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| 11 | |
How might a translation repressor protein function? |
| | A) | by binding to the mRNA so that it cannot bind a ribosome |
| | B) | by binding the enhancer to prevent looping and mRNA transcription |
| | C) | by binding the operator in an operon |
| | D) | by competing with transcription factors at the operon |
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| 12 | |
If a mechanism for controlling gene expression is in the cytoplasm, it most likely influences which of the following processes? |
| | A) | protein processing following translation |
| | B) | alternative splicing |
| | C) | the unwinding of euchromatin |
| | D) | DNA looping |
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| 13 | |
True or False: Once a protein is synthesized, it is immediately active. |
| | A) | True |
| | B) | False |
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| 14 | |
Two types of genes ordinarily keep the cell cycle functioning as it should. Which choice correctly explains the role of each these genes in this process? |
| | A) | Proto-oncogenes are turned on when cells are normal. Tumor suppressor genes are turned on when cells are cancerous and need to be killed. |
| | B) | Tumor suppressor genes promote the cell cycle and inhibit apoptosis. Proto-oncogenes inhibit the cell cycle and promote apoptosis. |
| | C) | Proto-oncogenes promote the cell cycle and inhibit apoptosis. Tumor suppressor genes inhibit the cell cycle and promote apoptosis. |
| | D) | Tumor suppressor genes are turned on when cells are normal. Proto-oncogenes are turned on when cells are cancerous and need to be killed. |
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| 15 | |
A normal stimulatory signal transduction pathway begins __________ and ends with __________. |
| | A) | at the plasma membrane; a proto-oncogene |
| | B) | at the plasma membrane; a tumor suppressor gene |
| | C) | at the nucleus; a proto-oncogene |
| | D) | at the nucleus; a tumor suppressor gene |
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| 16 | |
Which of the following lists the components of a normal signal transduction pathway that ends with a proto-oncogene? |
| | A) | a stimulatory growth factor, a plasma membrane receptor, signaling proteins, and a transcription factor |
| | B) | an inhibitory growth factor, a plasma membrane receptor, signaling proteins, and a transcription factor |
| | C) | signaling proteins external to the cell, a nuclear membrane receptor, and a stimulatory growth factor |
| | D) | signaling proteins external to the cell, a plasma membrane receptor, and a transcription factor |
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| 17 | |
A pathway that ends at the nucleus with a tumor suppressor gene is a(n) |
| | A) | cancer pathway. |
| | B) | protein processing pathway. |
| | C) | normal stimulatory signal transduction pathway. |
| | D) | normal inhibitory signal transduction pathway. |
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| 18 | |
A lack of p53 has been implicated in many human cancers. Which choice explains why? |
| | A) | A lack of p53 promotes apoptosis. |
| | B) | A lack of p53 inhibits the cell cycle. |
| | C) | A lack of p53 over-stimulates the cell cycle. |
| | D) | A lack of p53 prevents the cell cycle from being inhibited. |
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| 19 | |
In the early stages of a tumor, a single cell undergoes a mutation that causes it to divide repeatedly. For the tumor to survive, it requires __________, the development of which requires the release of growth factors that lead to __________. |
| | A) | more room; metastasis |
| | B) | a well-developed capillary network; angiogenesis |
| | C) | a well-developed capillary network; malignancy |
| | D) | motility; angiogenesis |
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| 20 | |
Initiation of new tumors far from the primary tumor is called |
| | A) | angiogenesis. |
| | B) | malignancy. |
| | C) | metastasis. |
| | D) | carcinogenesis. |
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