Can a single transcription factor regulate many genes?

Many genes are controlled by several different transcription factors, with a specific combination needed to turn the gene on; this is particularly true in eukaryotes and is sometimes called combinatorial regulation.

How are transcription factors involved in the regulation of gene expression?

Transcription factors are proteins involved in the process of converting, or transcribing, DNA into RNA. Other transcription factors bind to regulatory sequences, such as enhancer sequences, and can either stimulate or repress transcription of the related gene.

How can transcription factors themselves be regulated?

Many transcription factors use one or the other of two opposing mechanisms to regulate transcription: histone acetyltransferase (HAT) activity – acetylates histone proteins, which weakens the association of DNA with histones, which make the DNA more accessible to transcription, thereby up-regulating transcription.

Can transcription factors regulate genes in eukaryotes?

Gene expression in eukaryotic cells is regulated by repressors as well as by transcriptional activators. In some cases, eukaryotic repressors simply interfere with the binding of other transcription factors to DNA (Figure 6.30A).

How do transcription factors recognize specific DNA sequences?

Transcription factors recognize and bind to specific DNA sequences called promotor or enhancer sequences. Other transcription factors called activators target enhancer sequences that initiate the bending of the DNA to allow interaction with the proteins bound to the promoter region. …

How is it possible for a single gene to encode more than one polypeptide?

How is it possible for a single gene to encode more than one polypeptide? Exons in mRNA can be spliced together in different combinations. In translation, tRNA molecules bring amino acids to the ribosome.

How do transcription factors recognize their binding site on the DNA?

What are the roles of transcription factors?

Transcription factors are vital molecules in the control of gene expression, directly controling when, where and the degree to which genes are expressed. They bind to specific sequences of DNA and control the transcription of DNA into mRNA.

How does regulation of transcription in eukaryotes differ from regulation of transcription in prokaryotes?

Therefore, in prokaryotic cells, the control of gene expression is mostly at the transcriptional level. Eukaryotic gene expression is regulated during transcription and RNA processing, which take place in the nucleus, and during protein translation, which takes place in the cytoplasm.

How do transcription factors affect gene expression?

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. Repressors decrease transcription. Groups of transcription factor binding sites called enhancers and silencers can turn a gene on/off in specific parts of the body.

What determines how much a gene is transcribed?

Various factors control how much a gene is transcribed. For instance, how tightly the DNA of the gene is wound around its supporting proteins to form chromatin can affect a gene’s availability for transcription. Proteins called transcription factors, however, play a particularly central role in regulating transcription.

Where are the binding sites for transcription factors located?

The binding sites for transcription factors are often close to a gene’s promoter. However, they can also be found in other parts of the DNA, sometimes very far away from the promoter, and still affect transcription of the gene. The flexibility of DNA is what allows transcription factors at distant binding sites to do their job.

How do transcription factors work as nuclear messengers?

Transcription factors may also be directly activated by ligands such as glucocorticoids and vitamins A and D. Transcription factors may therefore convert transient environmental signals at the cell surface into long-term changes in gene transcription, thus acting as “nuclear messengers.”

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