What do zinc fingers bind to?

What do zinc fingers bind to?

The zinc-finger domain is one of the most frequently utilized DNA-binding motif found in eukaryotic transcriptional factors. The binding of a zinc-finger domain to its target site juxtaposes three base pairs on DNA to a few amino acids in the α-helix structure.

What does the transcription factor do?

Transcription factors are proteins involved in the process of converting, or transcribing, DNA into RNA. Transcription factors include a wide number of proteins, excluding RNA polymerase, that initiate and regulate the transcription of genes.

What is the transcription initiation complex?

Together, the transcription factors and RNA polymerase form a complex called the transcription initiation complex. This complex initiates transcription, and the RNA polymerase begins mRNA synthesis by matching complementary bases to the original DNA strand.

What does it mean to say a DNA sequence is highly conserved?

Conservation indicates that a sequence has been maintained by natural selection. A highly conserved sequence is one that has remained relatively unchanged far back up the phylogenetic tree, and hence far back in geological time.

What is a major disadvantage to a bacterial cell of having an operon?

What is a major disadvantage to a bacterial cell of having an operon? If there is a mutation in a regulatory region, none of the proteins will be synthesized. RNA polymerase. They give the cell tight control over transcription.

What is the difference between a Regulon and an operon?

An operon is one or more genes transcribed into a single RNA molecule and under the control of a single regulatory site, while a regulon is more than one operon that is under control of a single regulatory protein.

What are the two types of operons?

Operons are of two types, inducible and repressible.

What is a bacterial operon?

Bacterial Operons Are Coregulated Gene Clusters In addition to being physically close in the genome, these genes are regulated such that they are all turned on or off together. Grouping related genes under a common control mechanism allows bacteria to rapidly adapt to changes in the environment.

What turns the lac operon off?

An operon is a group of genes that are regulated together. When lactose is not present, the DNA-binding protein called ► lac repressor binds to a region called the operator, which switches the lac operon off. When lactose binds to the repressor, it causes the repressor to fall off the operator, turning ► the operon on.

What is lac Z?

The gene product of lacZ is β-galactosidase which cleaves lactose, a disaccharide, into glucose and galactose. lacY encodes Beta-galactoside permease, a membrane protein which becomes embedded in the cytoplasmic membrane to enable the cellular transport of lactose into the cell.

What is a repressor?

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 the repressor code?

The lacZYA operon houses genes encoding proteins needed for lactose breakdown. 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.

What does the presence of lactose do to the repressor?

If both glucose and lactose are both present, lactose binds to the repressor and prevents it from binding to the operator region. The block of lac gene transcription is thus lifted, and a small amount of mRNA is produced.

Do repressors bind to enhancers?

Transcriptional repressors can bind to promoter or enhancer regions and block transcription. Like the transcriptional activators, repressors respond to external stimuli to prevent the binding of activating transcription factors.

How do enhancers and silencers work?

Enhancers function as a “turn on” switch in gene expression and will activate the promoter region of a particular gene while silencers act as the “turn off” switch. Though these two regulatory elements work against each other, both sequence types affect the promoter region in very similar ways.

What happens if a promoter is deleted?

The contribution of a region of the promoter can be observed by the level of transcription. If a mutation or deletion changes the level of transcription, then it is known that that region of the promoter may be a binding site or other regulatory element.

What is the difference between an enhancer and a promoter?

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.

What are enhancers and silencers?

Enhancers have the ability to greatly increase the expression of genes in their vicinity. More recently, elements have been identified that decrease transcription of neighboring genes, and these elements have been called silencers. This enhancer is located in the intron of the gene.

Is enhancer a promoter?

Enhancers do not act on the promoter region itself, but are bound by activator proteins. These activator proteins interact with the mediator complex, which recruits polymerase II and the general transcription factors which then begin transcribing the genes.

Do bacteria have enhancers?

Once thought to be unique to eukaryotes, enhancer-like elements have been discovered in a wide variety of bacteria. The regulatory proteins that bind to these bacterial enhancers must contact RNA polymerase to activate transcription. Paradigms for each of these methods are found in bacterial systems.

Are enhancers and silencers transcription factors?

Transcription factors are proteins that help turn specific genes “on” or “off” by binding to nearby DNA. Transcription factors that are activators boost a gene’s transcription. Groups of transcription factor binding sites called enhancers and silencers can turn a gene on/off in specific parts of the body.

Do enhancers encode DNA binding proteins?

Enhancers are classically defined as cis-acting DNA sequences that can increase the transcription of genes. First, enhancers are scattered across the 98% of the human genome that does not encode proteins, resulting in a large search space (billions of base pairs of DNA).

What are enhancers in gene regulation?

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.

What is the difference between exons and introns?

Introns and exons are nucleotide sequences within a gene. Introns are removed by RNA splicing as RNA matures, meaning that they are not expressed in the final messenger RNA (mRNA) product, while exons go on to be covalently bonded to one another in order to create mature mRNA.

Is an activator a transcription factor?

A transcriptional activator is a protein (transcription factor) that increases transcription of a gene or set of genes. Most activators are DNA-binding proteins that bind to enhancers or promoter-proximal elements. The DNA site bound by the activator is referred to as an “activator-binding site”.

What are epigenetic modifications?

Epigenetic modifications are heritable chemical or physical changes in chromatin. There are two types of epigenetic modifications – DNA methylation and histone modifications (16).