BIO 325 Exam 3 Practice QuestionsAn operon is a cluster of functionally-related genes that are controlled by a shared operator. Operons consist of multiple genes grouped together with a promoter ciclo boldenona y winstrol an operator. Operons are present in prokaryotes bacteria usulaly archaeabut are absent in eukaryotes. In some situations multiple operons are controlled by the same regulatory protein; in these cases the operons form a regulon. Operons are regions of DNA that contain clusters of related genes. They are made up of a promoter region, an operator, and multiple related genes. The operator can be located either within involve promoter or anabolic pathways involved in the synthesis of essential molecules are usually regulated by the promoter and the genes.
Gene Regulation Flashcards | Quizlet
What would be the phenotype of a mutation that altered lac repressor function? A common DNA structural feature involved in gene regulatory systems is. How do negative regulators such as the lac repressor prevent RNA polymerase from initiating transcription? How do positive regulators stimulate initiation of transcription by RNA polymerase? Catabolic pathways that break down complex substances into more usable units are usually regulated by the.
Anabolic pathways involved in the synthesis of essential molecules are usually regulated by. Which statement is true regarding global gene regulation in bacteria. Alternative sigma factors recognizing different promoters carry out global gene regulation. How is glucose involved in the catabolite repression of the lactose operon? A common amino acid motif found in many of the polypeptides that function as repressors is.
How does tryptophan, the end product of the trp operon, function in the regulation of the operon? It binds to the repressor and only then can this complex bind to DNA preventing transcription of the operon. What term describes a second level of regulation of the trp operon that occurs in TrpR- mutants suggesting that it is repressor independent? How are complex processes such as sporulation, synthesis of flagella, and nitrogen fixation that require the transcription of multiple sets of genes regulated in bacteria?
Cascades of sigma factors synthesized in a temporal order, allow the turning on of successive sets of genes. As a general principle of gene regulation through operons, regulatory genes encode. In the trp operon, attenuation occurs through the recognition of two Trp codons in the leader sequence. What would happen if these two codons were mutated to stop codons?
This operon will be insensitive to attenuation by tryptophan, The structural genes will be transcribed in the presence or absence of tryptophan, The tryptophan biosynthetic enzymes will be synthesized.
All of these results will take place. Initiation of transcription by RNA polymerase involved the binding of which of the following subunits to the core enzyme? The transition from transcriptional initiation to elongation. Proteins that undergo reversible changes in conformation when bound to another molecule are.
A single DNA unit that enables the simultaneous regulation of more than one gene in response to environmental changes is. Alterations to DNA sites such as promoters and operators can act. Which of the following choices is NOT a correct description of a reporter gene? The sigma factor that mediates a global heat shock response in E.
In the regulation of the trp operon, tryptophan acts as. Posttranscriptional controls of gene expression in bacteria often serve to fine-tune the amount of protein needed. Because there is no nuclear membrane in prokaryotes, transcription and translation from a single gene can be taking place at the same. Negative regulation of gene expression usually takes place through enhancement of RNA polymerase activity. Positive regulators actually physically bind to RNA polymerase and enhance the enzyme's ability to initiate transcription.
The concept that proteins bind to DNA and regulate transcription holds true for both positive as well as negative regulation of gene expression. Attenuation of gene expression is unique to prokaryotes, because it requires translation of a leader sequence at the same time transcription is taking place.
A chaperone protein is used to aid in the transport of other proteins across cellular membranes. An underlying principle of prokaryotic gene regulation is that it occurs through the binding of regulatory proteins to specific DNA sequences.
There is only one site on the operator to which the lac repressor binds. In the trp operon, the protein repressor alone cannot bind to the operator to be a negative regulator. The mechanisms of gene regulation discovered in E. In prokaryotes, the gene regulation primarily occurs by either blocking or enhancing transcription.
The occurrence of constitutive mutations of all three of the lactose utilizing enzymes indicates that their synthesis is regulated together, probably by another gene.
In the operon model of gene regulation, transcription is shut off by the binding of the repressor to the promoter. Both inducers and corepressors lead to allosteric alterations in the repressor molecule. The presence of a diffusible gene product protein is a requirement for regulatory genes to act in trans. A distinguishing feature of control of gene expression in prokaryotes is that transcription and translation occur completely independently of each other.
Attenuation of the trp operon requires the presence of tryptophanyl-tRNAtrp. In a repressible operon, the repressor alone can bind to the operator and shut down transcription.