Explain how the presence of glucose represses the gal structural genes?
Bacterial genes are often found in operons. Genes in an operon are transcribed as a group and have a single promoter.
Each operon contains regulatory DNA sequences, which act as binding sites for regulatory proteins that promote or inhibit transcription.
Regulatory proteins often bind to small molecules, which can make the protein active or inactive by changing its ability to bind DNA.
Some operons are inducible, meaning that they can be turned on by the presence of a particular small molecule. Others are repressible, meaning that they are on by default but can be turned off by a small molecule.
We tend to think of bacteria as simple. But even the simplest bacterium has a complex task when it comes to gene regulation! The bacteria in your gut or between your teeth have genomes that contain thousands of different genes. Most of these genes encode proteins, each with its own role in a process such as fuel metabolism, maintenance of cell structure, and defense against viruses. Some of these proteins are needed routinely, while others are needed only under certain circumstances. Thus, cells don't express all the genes in their genome all the time. You can think of the genome as being like a cookbook with many different recipes in it. The cell will only use the recipes (express the genes) that fit its current needs.
How is gene expression regulated?
There are various forms of gene regulation, that is, mechanisms for controlling which genes get expressed and at what levels. However, a lot of gene regulation occurs at the level of transcription. 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. Let's take a closer look at how genes are regulated in bacteria.
In bacteria, genes are often found in operons:- In bacteria, related genes are often found in a cluster on the chromosome, where they are transcribed from one promoter (RNA polymerase binding site) as a single unit. Such a cluster of genes under control of a single promoter is known as an operon. Operons are common in bacteria, but they are rare in eukaryotes such as humans. Any genes play specialized roles and are expressed only under certain conditions, as described above. However, there are also genes whose products are constantly needed by the cell to maintain essential functions. These housekeeping genes are constantly expressed under normal growth conditions ("constitutively active"). Housekeeping genes have promoters and other regulatory DNA sequences that ensure constant expression.
Explain how the presence of glucose represses the gal structural genes?
Explain each step of the diagram (ie. presence of
glucose causes an inhibition of... etc.)
-GLUCOSE GLUCOSE INACTIVATION MIG1 GALA mRNA INDUCTION PATHWAY GALEGAL GALACTOSE 50 X POSITIVE FEEDBACK GAL GAL10 GAL7 GAL2 mRNA 100 X GAL3 Fig. 5. Model for glucose repression of the GAL genes. The numbers shown refer to the effect of glucose at various levels of regulation Thus, GALA is repressed S-fold by MIG1 in the presence of glucose. The MIG/GALA signal is amplified by a...
How would you explain the presence of bacterial genes being present on the genome of their eukaryotic host, as observed in mealybugs? horizontal gene transfer random frameshift mutation intragenomic recombination recent common ancestry
help please
How can eukaryotic structural genes involved in shared metabolic functions be coordinately (at the same time) expressed? by transcription factors that recognize shared consensus sequence in promoters. by several transcription factors that are coded by similar regulatory genes. by the presence of structures analogous to bacterial operons By sharing enhancers
For the lac genotypes shown, predict whether the
structural genes (Z) are constitutive, permanently
repressed, or inducible in the presence of lactose
For the lac genotypes shown, predict whether the structural genes (Z) are constitutive, permanently repressed, or inducible in the presence of lactose
how would you explain the presence of bacterial genes being
present on the genome of
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The presence of glucose in the environment typically causes catabolite repression. Explain why this confers an advantage to a bacterium
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Lac Operon IPOZY v3 In the genotype presented (genomic plus plasmid genes), which of the following statements is consistent with the expression phenotype? genome: I+P+ O- Z+ Y- plasmid: I+ P- O+ Z- Y+ constitutive expression of β-gal and permease induced in the presence of lactose constitutive expression of β-gal only constitutive expression of β-gal and permease β-gal and permease induced in the presence of lactose constitutive expression of permease and β-gal induced in the presence of lactose
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