26 Questions
What is the primary level of regulation of gene expression in prokaryotes?
Transcriptional level
What is the function of repressors in transcriptional regulation?
To inhibit gene transcription
What is the term for the removal of introns and joining of exons in mRNA?
Splicing
What is the term for the regulation of gene expression through chemical modifications to DNA or histone proteins?
Epigenetic regulation
What is the term for the addition of a 7-methylguanosine cap to the 5' end of mRNA?
Capping
What is the term for the regulation of gene expression at the level of mRNA translation into protein?
Translational regulation
What is the direct consequence of rapid transcription on splicing efficiency?
Decreased splicing efficiency
How does the organization of chromatin influence gene expression?
It regulates gene expression by altering transcription speed
What is the estimated number of proteins synthesized from the 20,000 human mRNAs?
Between 250,000 and 1 million
What is the mechanism that allows for the coordinated regulation of genes in eukaryotes?
Bidirectional promoters
What is the purpose of topologically associated domains (TADs) in gene regulation?
To regulate gene expression by supercoiling
How do transcription factories contribute to the regulation of gene expression?
By creating high concentrations of transcription factors
What is the result of alternative splicing in eukaryotes?
The production of different proteins from the same gene
What is the consequence of rapid transcription on post-transcriptional modification?
Decreased methylation of adenines
What is the reason for the difference in time taken for transcription of a 100 megabase gene in humans and yeast?
Difference in the duration of the cell cycle
What is the primary rate-limiting step in the expression of a 100 megabase gene?
Transcription
What is the function of the CTD modification in the regulation of gene expression?
To coordinate and order the processes
What is the term for the combination of RNA and proteins that are added to the RNA molecule during processing?
Messenger ribonucleoprotein
What is the term for the modifications made to the RNA molecule after transcription, including splicing and addition of proteins?
Post-transcriptional modification
What is the term for the phenomenon where the mRNA molecule is marked with information that determines its stability and translation in the cytoplasm?
RNA imprint
What is the benefit of the simultaneous occurrence of translation and transcription in procaryotes?
It helps the RNA polymerase to stimulate the elongation of transcription
What is the consequence of the interaction between ribosomes and RNA polymerase in procaryotes?
The cell interprets it as a lack of the messenger, thus stimulating the elongation of transcription
What is the difference between the coupling of transcription and translation in procaryotes and eucaryotes?
In procaryotes, it is direct, while in eucaryotes, it is mediated by the necessary export of the nucleus
What is the rate of elongation of transcription in eucaryotes?
1-2 Kb/min
What is the term for the coupling of two stages of gene regulation?
Acoplamiento
What is the consequence of the coupling of two stages of gene regulation?
The control of one stage affects the other
Study Notes
Gene Regulation
Transcriptional Regulation
- Refers to the regulation of gene expression at the transcription level
- Involves the control of transcription factor binding to specific DNA sequences
- Transcription factors can either stimulate (activators) or inhibit (repressors) gene transcription
- Examples of transcriptional regulation:
- Lac operon in E. coli: a repressor protein binds to the operator sequence, preventing transcription of the lac genes
- Inducible genes: transcription is induced in response to specific signals or stimuli
Translational Regulation
- Refers to the regulation of gene expression at the translation level
- Involves the control of mRNA translation into protein
- Mechanisms of translational regulation:
- mRNA stability and degradation
- Initiation of translation
- Elongation of translation
- MicroRNA-mediated regulation
Post-transcriptional Modification
- Refers to the chemical modifications made to mRNA after transcription
- Examples of post-transcriptional modifications:
- Capping: the addition of a 7-methylguanosine cap to the 5' end of mRNA
- Polyadenylation: the addition of a poly(A) tail to the 3' end of mRNA
- Splicing: the removal of introns and joining of exons
- Editing: the alteration of individual nucleotides in mRNA
Gene Expression in Prokaryotes
- Prokaryotes lack a true nucleus, and gene expression is primarily regulated at the transcriptional level
- Mechanisms of gene expression in prokaryotes:
- Operons: a group of genes that are transcribed together and regulated by a single promoter
- Repressors: proteins that bind to the operator sequence, preventing transcription
- Inducers: molecules that bind to repressors, allowing transcription to occur
Epigenetic Regulation
- Refers to the regulation of gene expression through chemical modifications to DNA or histone proteins
- Epigenetic modifications can be inherited through cell division
- Examples of epigenetic regulation:
- DNA methylation: the addition of a methyl group to cytosine residues in DNA
- Histone modification: the addition of various chemical groups to histone proteins
- Chromatin remodeling: the reorganization of chromatin structure to allow or block transcription
Test your understanding of gene regulation, including transcriptional regulation, translational regulation, post-transcriptional modification, gene expression in prokaryotes, and epigenetic regulation. Learn about the mechanisms that control gene expression and how they impact cellular processes.
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