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.
Want to see more full solutions like this?
Chapter 13 Solutions
Genetic Analysis: An Integrated Approach (3rd Edition)
- Define the following terms: a. chemotaxis b. lac operon c. 80S ribosome d. mRNA secondary structure e. mRNA scanningarrow_forwardWhich of the following is generally true about eukaryotic gene regulatory regions? a. All regulatory regions lie within 200 base pairs of the promoter. b. Promoters are typically under control of a single regulatory sequence. c. Promoters are usually blocked through the action of repressors d. Enhancer sequences can be located thousands of base pairs upstream or downstream from the promoter.arrow_forwardPut the following processes in order of their occurrence during expression of a eukaryotic gene: a. mRNA processing c. transcription b. translation d. RNA leaves nucleusarrow_forward
- 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_forwardThrough alternative splicing, eukaryotes (a) reinforce gene inactivation (b) prevent transcription of heterochromatin (c) produce related but different proteins in different tissues (d) amplify genes to meet the requirement of high levels of a gene product (e) bind transcription factors to enhancers to activate transcriptionarrow_forwardIn the given below characteristics which are typical of a eukaryotic gene that can be transcribed? 1. The core promoter is wrapped around a nucleosome. 2. The core promoter is found in a nucleosome-free region. 3. The terminator is wrapped around a nucleosome. 4. None of the above characteristics is typical of such a gene.arrow_forward
- Molecules in higher eukaryotes that are directly involved in gene silencing include all of the following except a. miRNA b. argonaute c. microprocessor d. glycosylasearrow_forwardE. coli are grown on a medium containing lactose. Once glucose is added to the medium, the bacteria stop fermenting lactose. Which of the following BEST explains the observed effect? A. Cellular levels of cAMP are lowB.Glucose is bound to the promoter C. Repressor protein is bound to the operator D. Repressor protein is bound to the promoterarrow_forwardIn considering the 7 levels of gene regulation, which of the following mechanisms acts at first level? a. repressor binding to sequence blocking the promoter b. miRNA silencing c. differential processing of RNA d. protein modification e. answer may vary depending if this occurs in a prokaryote or a eukaryotearrow_forward
- Give one example of a prokaryotic system of gene expression that is more complicated (duringtranscription at the promoter) than its corresponding eukaryotic system of gene expression.A. prokaryotes require general transcription factors to initiate transcriptionB. prokaryotes typically have activator and repressor DNA sequences thousands of nucleotides awayC. prokaryotes have three classes of RNA polymerasesD. prokaryotes always have their DNA tightly packed into higher-level structures than nucleosomesE. prokaryotes usually have polycistronic mRNAarrow_forwardDefine the following terms:a. cistronb. operonc. miRNAd. siRNAe. snoRNAarrow_forwardMatch each of the following eukaryotic gene regulatory mechanisms or component to it's best description. v histone modification that causes chromatin to loosen A. enhancer increasing gene access B. acetyl group different mRNA transcripts are produced from the same starting DNA due to how exons and introns are interpreted C. methyl group v histone or DNA modification that causes chromatin to condense D. alternative RNA splicing decreasing gene access v eukaryotic control element where repressor or activator proteins can bind which can repress or promote transcriptionarrow_forward
- Biology (MindTap Course List)BiologyISBN:9781337392938Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. BergPublisher:Cengage Learning