Concept explainers
Bacterial genomes frequently contain groups of genes organized into operons. What is the biological advantage of operons to bacteria? Identify the regulatory components you would expect to find in an operon. How are the expressed genes of an operon usually arranged?
To review:
The genome of bacteria contains operons that consist of a group of genes. Describe the advantage of these operons to bacteria. Explain the expected regulatory components present in an operon. Also illustrate the arrangement of expressed genes of an operon?
Introduction:
The first operon was discovered in E. coli - “lac operon”- by a group of scientists- Francois Jacob, Andre Michel Lwoff and Jacques Monod in
Explanation of Solution
The gene expression in prokaryotes is completely dependent on the availability of the nutrients in a cell. To save energy and upsurge efficiency, bacteria have operons. The stretch of DNA that regulates the activity of structural genes and a group of genes is referred to as operons. They are regulated by positive and negative gene regulation. A single operon will give expressions of many gene products that save the energy of bacteria and increase the efficiency by gaining large amount of functional proteins. As bacteria have coupled transcription and translation, as soon as the group of genes on an operon is transcribed, they are converted to proteins. The genes are located one after another which allows protein synthesis to be controlled under a single promoter. To control the expression, the operon is switched on or off, according to the need of a cell.
The operon has regulatory components- Promoter, repressor, and activators/inducer.
The expressed genes are arranged after the regulatory region of the gene in a fashion one after another.
Operons in bacteria are described and the subsequent facts related to it are explained.
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Chapter 14 Solutions
Mastering Genetics with Pearson eText -- Standalone Access Card -- for Genetic Analysis: An Integrated Approach (2nd Edition)
- A mutation that inactivates the repressor gene of the lac operon results in (a) the continuous transcription of the structural genes (b) no transcription of the structural genes (c) the binding of the repressor to the operator (d) no production of RNA polymerase (e) no difference in the rate of transcriptionarrow_forwardThe transcription of many bacterial genes relies on functional groups called operons, such as the tryptophan operon. What is an operon?arrow_forwardWhat does the lac operon consist of? How is the operator switch turned on and off in the expression of genes in this operon? Explain.arrow_forward
- If the two trp codons in the leader sequence were mutated to stop codons, what effect would it have on gene expression of that operon.arrow_forwardWhat would happen if the operator sequence of the lac operon contained a mutation that prevented the repressor protein from binding the operator? (Explain what would happen both in the presence and absence of lactose)arrow_forwardIn most experiments using the lac operon, researchers use the synthetic inducer IPTG to turn on operon expression, instead of lactose or allolactose. What do you think is the advantage of using IPTG?arrow_forward
- A bacterial cell is mutated and cannot create the repressor protein associated with the Lac operon. How will this affect the functioning of the Lac operon?arrow_forwardA mutation occurs in the 5′ UTR of the trp operon that reduces the ability of region 2 to pair with region 3. What will the effect of this mutation be when the tryptophan level is high? When the tryptophan level is low?arrow_forwardWhat is an operon? Describe the functions of regulators, promoters,and operators.arrow_forward
- If you add a co-eepressor to a repressor protein and that allows it to bind the operator is this a inducible, constitutive or repressible operon?arrow_forwardWhat are the major differences between an operon and a regulon?arrow_forwardHow does catabolite repression work on gal operon?How could you decide if one particular operon is under same catabolite repression as that for lac and gal operons.arrow_forward
- Biology (MindTap Course List)BiologyISBN:9781337392938Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. BergPublisher:Cengage Learning