Textbook Question
Predict how a mutation that caused continuous production of active p53 would affect the cell.
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Ch. 19 - Control of Gene Expression in Eukaryotes
Chapter 18, Problem 11
The Hawaiian bobtail squid (Euprymna scolopes) is able to glow from luminescent Vibrio fischeri bacteria held in its light organs. As it swims at night near the ocean surface, it adjusts the amount of light visible to predators below to match the light from the stars and moon. Predators have difficulty seeing the illuminated squid against the night sky. The bacteria glow in response to a molecule that regulates expression of genes involved in light-producing chemical reactions. The regulator controls production of the genes' mRNA. Therefore, the light-producing genes are under a. transcriptional control. b. translational control. c. post-translational control. d. negative control.
Verified step by step guidance1
Identify the key process described: The regulator molecule affects the expression of genes by controlling the production of mRNA.
Understand the types of gene control: Transcriptional control involves the process of transcribing DNA to mRNA, translational control involves the process of translating mRNA into proteins, and post-translational control involves modifications after protein synthesis.
Analyze the role of the regulator molecule: Since the regulator controls the production of mRNA, it is directly involved in the transcription process.
Match the process to the correct type of control: Because the regulator is affecting the production of mRNA, it is involved in transcriptional control.
Select the correct answer: The light-producing genes are under transcriptional control, so the correct answer is a. transcriptional control.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Transcriptional Control
Transcriptional control refers to the regulation of gene expression at the transcription stage, where DNA is transcribed into mRNA. This process is crucial for determining which genes are expressed in a cell at any given time. In the context of the Hawaiian bobtail squid, the regulator molecule influences the production of mRNA for light-producing genes, thereby controlling the amount of luminescence produced by the bacteria.
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03:57
Specific Transcription Factors
mRNA and Gene Expression
mRNA, or messenger RNA, is a type of RNA that conveys genetic information from DNA to the ribosome, where proteins are synthesized. The amount and timing of mRNA production are critical for gene expression, as they dictate how much of a particular protein is made. In the squid's case, the regulation of mRNA levels directly impacts the luminescent capabilities of the Vibrio fischeri bacteria, allowing the squid to adapt its glow.
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06:40Introduction to Regulation of Gene Expression
Light Production in Bioluminescence
Bioluminescence is the production and emission of light by living organisms, often through biochemical reactions involving luciferin and luciferase enzymes. In the Hawaiian bobtail squid, the luminescent bacteria utilize specific genes that encode these enzymes, enabling them to produce light. The regulation of these genes is essential for the squid's survival strategy, as it helps to camouflage the squid from predators by matching the ambient light conditions.
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Related Practice
Textbook Question
In the follow-up work to the experiment shown in Figure 19.6, the researchers used a technique that allowed them to see if two DNA sequences are in close physical proximity (association). They applied this method to examine how often an enhancer and the core promoter of the Hnf4a regulatory gene were near each other. A logical prediction is that compared with rats born to mothers fed a healthy diet, the Hnf4a gene in rats born to mothers fed a protein-poor diet would a. show no difference in how often the promoter and enhancer associated. b. never show any promoter–enhancer association. c. show a lower frequency of promoter–enhancer association. d. show a higher frequency of promoter–enhancer association.
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Textbook Question
One hypothesis for differences between humans and chimpanzees involves differences in gene regulation. A study using RNA-seq showed that the overall patterns of gene expression were similar in the liver and blood of the two species, but the expression patterns were strikingly different in the brain. How do these results relate to the hypothesis?
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