Biology
In prokaryotes, genes that encode enzymes of a metabolic pathway are usually clustered together on the chromosome in a region called an operon. A typical operon consists of regulatory sequences, like promoter, operator, terminator, and structural genes. Lac operon is an inducible operon that can be under negative control by lac repressor or positive control by CAP. In the absence of lactose, repressor binds to operator and blocks RNA polymerase from binding to promoter, thus no / low level of transcription of structural genes. In the presence of lactose, lactose will bind to repressor and change its conformation and prevent repressor from binding to operator, thus RNA polymerase can bind to promoter and transcription occurs. When both glucose and lactose are present, bacteria can selectively catabolise glucose instead of lactose. In the absence of glucose, the concentration of cAMP is high and cAMP binds to CAP and activates CAP, thus CAP binds to CAP-binding site and enhances rate of transcription. In the presence of glucose, concentration of cAMP is low and CAP not activated, thus CAP does not bind to CAP-binding site and transcription of structural genes occur as a low / basal rate.
- Q: Outline The Differences Between Prokaryotic Control Of Gene Expression With The Eukaryotic Model
In the prokaryotic model, the regulation of transcription is by the control of operons. However, in the eukaryotic model, it is via the control of transcription factors. In prokaryotes, transcription can occur simultaneously with translation as there...
- Transcription In Eukaryotic Cells
Transcription in Eukaryotic Cells What is transcription? Transcription is the process that creates RNA inside a cell. It is used to develop proteins inside the cytoplasm of a cell although the actual transcription happens in the nucleus and mitochondria....
- Initiation In Bacteria Needs 30s Subunits And Accessory Factors
KEY TERMS:A ribosome-binding site is a sequence on bacterial mRNA that includes an initiation codon that is bound by a 30S subunit in the initiation phase of protein synthesis. An initiation complex in bacterial protein synthesis contains a small ribosome...
- The Life Cycle Of Bacterial Messenger Rna
KEY TERMS:Nascent RNA is a ribonucleotide chain that is still being synthesized, so that its 3 end is paired with DNA where RNA polymerase is elongating. Monocistronic mRNA codes for one protein. Polycistronic mRNA includes coding regions representing...
- 4. Molecular Basis Of Inheritance
Click here for PDFNucleic acids (DNA & RNA) are the building blocks of genetic material.DNA is the genetic material in most of the organisms. RNA is the genetic material in some viruses. RNA mostly functions as messengers. STRUCTURE OF POLYNUCLEOTIDE...
Biology
Q: Explain how protein synthesis can be controlled at a transcriptional level in prokaryotes
In prokaryotes, genes that encode enzymes of a metabolic pathway are usually clustered together on the chromosome in a region called an operon. A typical operon consists of regulatory sequences, like promoter, operator, terminator, and structural genes. Lac operon is an inducible operon that can be under negative control by lac repressor or positive control by CAP. In the absence of lactose, repressor binds to operator and blocks RNA polymerase from binding to promoter, thus no / low level of transcription of structural genes. In the presence of lactose, lactose will bind to repressor and change its conformation and prevent repressor from binding to operator, thus RNA polymerase can bind to promoter and transcription occurs. When both glucose and lactose are present, bacteria can selectively catabolise glucose instead of lactose. In the absence of glucose, the concentration of cAMP is high and cAMP binds to CAP and activates CAP, thus CAP binds to CAP-binding site and enhances rate of transcription. In the presence of glucose, concentration of cAMP is low and CAP not activated, thus CAP does not bind to CAP-binding site and transcription of structural genes occur as a low / basal rate.
- Q: Outline The Differences Between Prokaryotic Control Of Gene Expression With The Eukaryotic Model
In the prokaryotic model, the regulation of transcription is by the control of operons. However, in the eukaryotic model, it is via the control of transcription factors. In prokaryotes, transcription can occur simultaneously with translation as there...
- Transcription In Eukaryotic Cells
Transcription in Eukaryotic Cells What is transcription? Transcription is the process that creates RNA inside a cell. It is used to develop proteins inside the cytoplasm of a cell although the actual transcription happens in the nucleus and mitochondria....
- Initiation In Bacteria Needs 30s Subunits And Accessory Factors
KEY TERMS:A ribosome-binding site is a sequence on bacterial mRNA that includes an initiation codon that is bound by a 30S subunit in the initiation phase of protein synthesis. An initiation complex in bacterial protein synthesis contains a small ribosome...
- The Life Cycle Of Bacterial Messenger Rna
KEY TERMS:Nascent RNA is a ribonucleotide chain that is still being synthesized, so that its 3 end is paired with DNA where RNA polymerase is elongating. Monocistronic mRNA codes for one protein. Polycistronic mRNA includes coding regions representing...
- 4. Molecular Basis Of Inheritance
Click here for PDFNucleic acids (DNA & RNA) are the building blocks of genetic material.DNA is the genetic material in most of the organisms. RNA is the genetic material in some viruses. RNA mostly functions as messengers. STRUCTURE OF POLYNUCLEOTIDE...