How Bacteria control their gene expression?

Bacteria have specific regulatory molecules that control whether a particular gene will be transcribed into mRNA. Often, these molecules act by binding to DNA near the gene and helping or blocking the transcription enzyme, RNA polymerase.

What are the controls of gene expression?

Gene expression is primarily controlled at the level of transcription, largely as a result of binding of proteins to specific sites on DNA. The regulator gene codes for synthesis of a repressor molecule that binds to the operator and blocks RNA polymerase from transcribing the structural genes.

How do you control and regulate gene expression?

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. Further regulation may occur through post-translational modifications of proteins.

What controls gene expression on and off?

Each cell expresses, or turns on, only a fraction of its genes at any given time. The rest of the genes are repressed, or turned off. The process of turning genes on and off is known as gene regulation. Signals from the environment or from other cells activate proteins called transcription factors.

What is positive control of gene expression?

In the case of positive control, the genes are expressed only when an active regulator protein, e.g. an activator, is present. Thus the operon will be turned off when the positive regulatory protein is absent or inactivated.

What are two ways of controlling gene expression in bacteria?

The most direct way to control the expression of a gene is to regulate its rate of transcription; that is, the rate at which RNA polymerase transcribes the gene into molecules of messenger RNA (mRNA).

What are three factors that affect gene expression?

Various factors, including genetic makeup, exposure to harmful substances, other environmental influences, and age, can affect expressivity. Both penetrance and expressivity can vary: People with the gene may or may not have the trait and, in people with the trait, how the trait is expressed can vary.

What is an example of gene expression?

Some simple examples of where gene expression is important are: Control of insulin expression so it gives a signal for blood glucose regulation. X chromosome inactivation in female mammals to prevent an “overdose” of the genes it contains. Cyclin expression levels control progression through the eukaryotic cell cycle.

What are two ways in which eukaryotic cells regulate gene expression?

Eukaryotic Repressors Gene expression in eukaryotic cells is regulated by repressors as well as by transcriptional activators. Like their prokaryotic counterparts, eukaryotic repressors bind to specific DNA sequences and inhibit transcription.

Why is control of gene expression important?

Genes encode proteins and proteins dictate cell function. Therefore, the thousands of genes expressed in a particular cell determine what that cell can do. Thus, control of these processes plays a critical role in determining what proteins are present in a cell and in what amounts.

What factors affect gene expression?

Environmental factors such as diet, temperature, oxygen levels, humidity, light cycles, and the presence of mutagens can all impact which of an animal’s genes are expressed, which ultimately affects the animal’s phenotype.

What is the difference between positive and negative control of gene expression?

In the case of negative control, the genes in the operon are expressed unless they are switched off by a repressor protein. In the case of positive control, the genes are expressed only when an active regulator protein, e.g. an activator, is present.

How is gene expression controlled in an eukaryotic cell?

Eukaryotic cells have similar mechanisms for control of gene expression, but they are more complex. Consider, for example, that prokaryotic cells of a given species are all the same, but most eukaryotes are multicellular organisms with many cell types, so control of gene expression is much more complicated.

How is the control of electron flow extrapolated to gene expression?

In recent years, photosynthetic control has also been extrapolated to the regulation of gene expression because mechanisms that are identical or similar to those that serve to regulate electron flow through the PET chain also coordinate the regulated expression of genes encoding photosynthetic proteins.

How is gene expression in the chloroplasts controlled?

Gene expression within the chloroplasts and nucleus is controlled through the activation of a network of kinases that are involved in chloroplast to nucleus retrograde signalling pathways.

How does the process of translation affect gene expression?

The process of translation offers additional opportunities for regulation by many proteins. For example, the translation of hemoglobin mRNA is inhibited unless iron-containing heme is present in the cell. There are also opportunities for “post-translational” controls of gene expression in eukaryotes.