Concept explainers
Devoting a few sentences to each, describes the following structures or complexes and their effects on eukaryotic gene expression:
a. Promoter
b. Enhancer
c. Silencer
d. RISC
e. Dicer
To analyze:
The following structures and their effects on eukaryotic gene expression
Promoter
Enhancer
Silencer
RISC
Dicer
Introduction:
Gene regulation is an important feature of all living organisms. A regulatory sequence is a stretch of the DNA that can increase or decrease the expression of the genes. These genes can control the expression of one or more genes. Controlling genes can be negative or positive regulators. Negative regulators control gene regulation by inhibiting transcription or translation. These gene regulatory elements include insulators, enhancers, promoters, silencers.
Explanation of Solution
Promoter:
It is the regulatory part of the DNA that is responsible for the initiation of the gene. It can be
The eukaryotic promoter contains a TATA box that provides a binding site for TATA-binding protein. This protein helps in the formation of the RNA polymerase transcriptional complex.
Enhancer:
It is another regulatory sequence that can be bound by the activator proteins. It surges the transcription of the gene. It is the cis-acting gene. It can be existing upstream or downstream of the gene it regulates. It may be present near or very far from the genes they regulate.
Silencer:
It is a cis-acting sequence that binds to the regulatory sequence known as a repressor. By binding to the silencer, repressor prevents the binding of RNA polymerase and transcription of DNA sequence. Therefore, it does not allow the expression of the gene into proteins. Silencer sequence can be present upstream or downstream of the promoter sequence. In eukaryotes, silencer controls the gene regulation at the transcription level.
RISC:
It is also known as the RNA induced silencing complex. It is ribonucleoprotein that is involved in gene silencing. When a cell contains double-stranded RNA, the enzyme dicer cuts the double-stranded RNA into fragments. These fragments attach to the RISC which results in denaturation of double-stranded RNA into single-stranded RNA. One of the strands is a biologically active guide strand and second is the passenger strand. RISC binds to the guide strand that directs gene silencing.
Dicer:
It is an enzyme that converts double-stranded RNA to small interfering RNA. It consists of one double-stranded RNA binding site and two domains that have RNase activity. This RNase activity breaks the RNA. Dicer activates RISC that is crucial for RNA interference. Dicer also converts pre-miRNA to micro-RNA.
Transcriptional regulatory elements are nucleic acid sequences that are important in gene regulation.
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Chapter 13 Solutions
Genetic Analysis Format: Kit/package/shrinkwrap
- Which of the following is characteristic of genes and gene regulation in both bacteria and eukaryotes? (a) promoters (b) non-coding DNA within coding sequences (c) enhancers (d) operons (e) DNA located in a nucleusarrow_forwardCompare and contrast regulation of gene expression in prokaryotes vs. eukaryotes.arrow_forwardWhich sequence is most likely to be found in a promoter? a) CGGTGTATATCGTAC b) GTACAGTCATCCCGT c) AAATCTACTACGATT d) GGGTTGGGTTGGGTTarrow_forward
- Explain how a gene knockdown reagent, such as RNAi or a morpholino, could interfere with expression of a gene without affecting the rate of transcription of the target gene.arrow_forwardEukaryotic cells have multiple complex mechanisms for the regulation of gene expression, but a regulatory mechanism they rarely (if ever) use is a. operons. b. regulatory proteins. c. transcriptional factors. d. promoters.arrow_forwardWith the aid of diagrams, and using specific examples, describe how gene expression is regulated in prokaryotes.arrow_forward
- To start transcription, RNA polymerase binds to a please explain your answer a.initiator complex b.promoter sequence c.trigger factor d.Rho factor e.Shine-Dalgarno sequencearrow_forwarda) what is a promoter and give the element and their functions of E.coli promoter b) what are eukaryotic transcription factor and list the class 2 general transcription factors and state their functionsarrow_forwardWhich of the following characteristics is typical of a eukaryotic gene that can be transcribed? a. The core promoter is wrapped around a nucleosome. b. The core promoter is found in a nucleosome-free region. c. The terminator is wrapped around a nucleosome. d. None of the above characteristics is typical of such a gene.arrow_forward
- Promoters are DNA sequences a. near a transcription start site b. bound to a repressor protein c. that inhibit transcription of a gene d. that stimulate ncRNA activityarrow_forwardIf eukaryotes have monocistronic genes, why is the number of known proteins more than the number of known genes? A. Post-translational modification B. Alternative splicing C. Base substitution D. Post-transcriptional modificationarrow_forwardWhich of the following parts of the eukaryotic promoter are bound by general transcription factors? Group of answer choices A promoter proximal elements B enhancer elements C specific promoter elements D the core promoter E the distal promoterarrow_forward
- Biology (MindTap Course List)BiologyISBN:9781337392938Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. BergPublisher:Cengage Learning