Question: What Is A Repressor In Biology?

A repressor is a protein that turns off the expression of one or more genes. The repressor protein works by binding to the gene’s promoter region, preventing the production of messenger RNA (mRNA).

What is a repressor in an operon?

repressor: any protein that binds to DNA and thus regulates the expression of genes by decreasing the rate of transcription. operon: a unit of genetic material that functions in a coordinated manner by means of an operator, a promoter, and structural genes that are transcribed together.

What is a repressor quizlet?

repressor. A protein that inhibits gene transcription. In prokaryotes, repressors bind to the DNA in or near the promoter. In eukaryotes, repressors may bind o control elements within enhancers, to activators, or to other proteins in a way that blocks activators from binding to DNA.

What are repressors and activators?

Activators (and sometimes inducers) instigate positive regulation, and repressors instigate negative regulation. When a repressor binds to an operon, the transcription process is slowed or halted.

What is a repressible operon in biology?

A repressible operon is one that is usually on but which can be repressed in the presence of a repressor molecule. The repressor binds to the operator in such a way that the movement or binding of RNA polymerase is blocked and transcription cannot proceed.

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Where is the repressor?

transcription. …“operators” where specialized proteins called repressors bind to the DNA just upstream of the start point of transcription and prevent access to the DNA by RNA polymerase. These repressor proteins thus prevent transcription of the gene by physically blocking the action of the RNA polymerase.

What is the repressor code?

The lacI gene codes for a protein called “the repressor” or “the lac repressor”, which functions to repressor of the lac operon. The gene lacI is situated immediately upstream of lacZYA but is transcribed from a lacI promoter.

Where is the repressor encoded quizlet?

a regulatory protein that, when not bound to the operator of an operon, greatly reduces transcription. a regulatory protein that greatly decreases operon transcription by binding to the operator. Where is the repressor encoded? in a regulatory gene, which is separate from the operon.

What is an operon in biology quizlet?

operon. a group of genes working together to make specific protein — composed of a promoter, regulator, operator, and structural genes. promoter. the site on the operon where RNA polymerase binds to start transcription. regulator.

What is an operon AP Bio quizlet?

operon. the operator, the promoter, and a coordinately regulated gene cluster whose products function in a common pathway. RNA polymerase. attaches to the DNA at the promoter and transcribes the operon’s genes.

What are enhancers DNA?

Enhancer sequences are regulatory DNA sequences that, when bound by specific proteins called transcription factors, enhance the transcription of an associated gene. Because DNA is folded and coiled in the nucleus, the enhancer may actually be located near the transcription start site in the folded state.

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What are promoters and enhancers?

An enhancer is a sequence of DNA that functions to enhance transcription. A promoter is a sequence of DNA that initiates the process of transcription. A promoter has to be close to the gene that is being transcribed while an enhancer does not need to be close to the gene of interest.

Is promoter a DNA?

​Promoter. A promoter is a sequence of DNA needed to turn a gene on or off. The process of transcription is initiated at the promoter. Usually found near the beginning of a gene, the promoter has a binding site for the enzyme used to make a messenger RNA (mRNA) molecule.

What is a inducible operon?

An inducible operon is one whose expression increases quantitatively in response to an enhancer, an inducer, or a positive regulator.

What is a DNA plasmid?

A plasmid is a small, circular, double-stranded DNA molecule that is distinct from a cell’s chromosomal DNA. Plasmids naturally exist in bacterial cells, and they also occur in some eukaryotes. Often, the genes carried in plasmids provide bacteria with genetic advantages, such as antibiotic resistance.

What is the operon hypothesis?

Operon Hypothesis – Enzyme Induction In bacteria, genes that code for proteins required for the same metabolic or biosynthetic pathway are often clustered in groups called operons The lac operon in E. The operator gene binds the repressor protein, which determines whether the structural gene is switched on or off.

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