Ch. 19 - Control of Gene Expression in Eukaryotes

Freeman - Biological Science 7th Edition

Freeman7th EditionBiological ScienceISBN: 9783584863285Not the one you use?Change textbook

Freeman 7th Edition

Ch. 19 - Control of Gene Expression in Eukaryotes

Problem 11

Chapter 19, 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 undera. transcriptional control.b. translational control.c. post-translational control.d. negative control.

Verified step by step guidance

Identify the level at which the regulator is acting in the gene expression process. The problem states that the regulator controls the production of mRNA.

Understand the different types of gene expression control: Transcriptional control involves the process of transcribing DNA to mRNA, translational control involves the process of translating mRNA into protein, and post-translational control involves modifications after the protein has been made.

Analyze the statement that the regulator controls the production of mRNA. This indicates that the control is exerted at the stage of transcription, where mRNA is being synthesized from DNA.

Recall that transcriptional control is the regulation of the rate at which genes are transcribed to produce mRNA. It is the first level of gene expression control and determines which genes are expressed and when.

Conclude that since the regulator affects the production of mRNA, the control is at the transcriptional level, not at the translation or post-translation stages.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.

Video duration:

54s

Was this helpful?

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, indicating that these genes are controlled at the transcriptional level.

Gene Expression Regulation

Gene expression regulation encompasses the various mechanisms that cells use to increase or decrease the production of specific gene products, such as proteins. This regulation can occur at multiple stages, including transcription, translation, and post-translation. Understanding how the squid's light-producing genes are regulated helps explain how it can adapt its luminescence to avoid predation.

Luminescent Bacteria Symbiosis

The symbiotic relationship between the Hawaiian bobtail squid and Vibrio fischeri bacteria is a prime example of mutualism, where both organisms benefit. The bacteria provide bioluminescence, which the squid uses for camouflage, while the squid offers a nutrient-rich environment for the bacteria. This interaction highlights the importance of microbial partnerships in ecological adaptations and survival strategies.

Recommended video:

Guided course

02:34

Symbiosis

Related Practice

Textbook Question

Predict how a mutation that caused continuous production of active p53 would affect the cell.

836

views

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

786

views

Textbook Question

Imagine repeating the experiment on epigenetic inheritance that is shown in Figure 19.6. You measure the amount of radioactive uridine (U) incorporated into Hnf4a mRNA in counts per minute (cpm) to determine the level of Hnf4a gene transcription in rats born to mothers fed either a normal diet or a low-protein diet. The results are 11,478 cpm for the normal diet and 7368 cpm for the low-protein diet. For this problem, your task is to prepare a graph similar to the one at the bottom of Figure 19.6 that shows the normalized results for the low-protein diet relative to the normal diet. Normalizing values means that the value obtained from one condition is expressed as 1.0 (the norm; the normal diet in this case) and the values obtained from any other conditions (low-protein diet in this case) are expressed as decimal values relative to the norm.

1133

views