1. what is a ubiquitin tag? What role do these tags play in gene regulation? 2.
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Question
1. what is a ubiquitin tag? What role do these tags play in gene regulation?
2. What is RNA interference? Give an example of the two types of RNA involved.
3. list 3 mechanisms of post-transcriptional regulations.
4. Describe how histones interact with the TATA box to regulate gene expression.
5. What are two mechanisms utilized by cells to repress transcription?
6. List two ways cells activate transcription.
7. What are general transcription factors and combinatorial gene regulation?
a. How does this relate to the 'Proteins outnumber genes' dilemma? Provide an example.
b. How does this relate to coordinated activation of 'sets of genes' in specific cell type?
Explanation / Answer
1)what is a ubiquitin tag? What role do these tags play in gene regulation?
Ubiquitin is a small protein and occurs in eukaryotic organisms, this can bind to the substrate protein and can change its function.
Through the process of ubiquitination (where ubiquitin goes and binds to the chromatin structure), ubiquitin can alter the gene expression. The presence of ubiquitin will make the gene inactive.
2.What is RNA interference? Give an example of the two types of RNA involved.
RNA interference (RNAi) is a biological process, though this we can inhibit the gene expression by destroying the specific mRNA molecule synthesizing the protein using the complementary RNA molcecule against the mRNA.
Here two types of RNA molecules can be seen
a)miRNA (micro RNA)
b)siRNA(small interfering RNA)
3. list 3 mechanisms of post-transcriptional regulations.
a)Capping: An additional GTP molecule is added to 5’ end of the primary RNA transcript, which protects them from degradation and ribosomal binding.
b)Splicing: Here the noncoding regions called introns will be removed using spliceosome complex and coding regions called exons will be brought tougher.
c) Polyadenylation: A stretch of adenine bases will be added at the 3; end and it will protect the mRNA and increases its half life.
4. Describe how histones interact with the TATA box to regulate gene expression.
TATA box found in promoter region and it acts as a binding site for either transcription factors or histone. When the gene is associated with histone, the gene transcription will not occur, but whenever it dissociates from this region, the transcription factor will bind and transcribe the gene.
5)What are two mechanisms utilized by cells to repress transcription?
a)Blocks the binding of RNA polymerase to DNA.
b) Through histone deacetylase (which deacetylase the histone), the interaction between the DNA and histone will be made stronger and thereby block the transcription.
6. List two ways cells activate transcription.
a)Through histone acetylase of histone proteins, which dissociates the histone from DNA, we can allow the RNA polymerase to carry out the transcription.
b)The presence of coactivators enhances the chances of DNA transcription
7. What are general transcription factors and combinatorial gene regulation?
General transcription factors are the protein which binds to specific site on DNA and enhance the transcription.(synthesis of RNA from DNA)
combinatorial gene regulation allows a organism to have innumerable expression pattern with the available limited number of transcription factors.
a)How does this relate to the 'Proteins outnumber genes' dilemma? Provide an example.
The number of genes present can code for a huge number of mRNAs with different combinations. For example, human genome has 20,325 genes , but it can encode 100000 mRNAs and which can specify more than a million proteins.
b)How does this relate to coordinated activation of 'sets of genes' in specific cell type?
Each cell type will have specific set of receptors, so these activated receptor will influence the transcription of specific gene needed for that specific cell type, unwanted genes will never be transcribed.
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