Regulation of Gene Expression Quiz

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Questions and Answers

What role does transposase play in the genome?

It mediates the movement of transposable elements. (correct)

It synthesizes RNA from DNA.

It promotes the replication of DNA.

It functions as a transcription factor.

Which element is primarily responsible for the initiation of transcription?

Silencer elements.

TATA box. (correct)

Enhancer elements.

Response elements.

What distinguishes cis-acting elements from trans-acting factors?

Cis-acting elements are present on the same gene they regulate. (correct)

Cis-acting elements interact with transcription factors.

Cis-acting elements can regulate other genes.

Cis-acting elements are produced by the gene being transcribed.

Which of the following is NOT a type of signaling molecule that binds to response elements?

Calcium ions. Signup and view all the answers

How do enhancers exert their regulatory effects on transcription?

They can function even if separated from the promoter. Signup and view all the answers

How do steroid hormones primarily affect gene expression?

By directly binding to steroid response elements in DNA. Signup and view all the answers

Which of the following correctly describes the role of CREB protein?

It activates genes by binding to responsive element sequences on DNA. Signup and view all the answers

What is a common pharmacological mechanism used to treat inflammatory disorders with steroid drugs?

Suppressing transcription of inflammatory mediators. Signup and view all the answers

In the treatment of diabetes mellitus, how does insulin affect gene expression?

By affecting the activity of tyrosine kinase receptors and downstream signaling. Signup and view all the answers

How do calcineurin inhibitors like cyclosporine work to suppress immune activity?

By inhibiting calcineurin, a phosphatase that activates transcription factors. Signup and view all the answers

What is the primary outcome of alternative splicing and polyadenylation of mRNA?

It allows multiple proteins to be produced from a single gene. Signup and view all the answers

What mechanism is described by a change in a single nucleotide in mRNA leading to altered protein size?

RNA editing Signup and view all the answers

Which factor is NOT mentioned as influencing the stability of mRNA?

Gene promoter sequences Signup and view all the answers

What role do microRNAs play in post-transcriptional regulation?

They can cause mRNA degradation and translational repression. Signup and view all the answers

At what level do most eukaryotic translational controls exert their effects?

During the initiation of protein synthesis Signup and view all the answers

What function do lysosomal enzymes primarily serve in cellular health?

Digesting phagocytosed microorganisms and cellular debris Signup and view all the answers

Which of the following statements about eukaryotic initiation factor 2 (eIF2) is accurate?

The action of eIF2 can be inhibited through phosphorylation. Signup and view all the answers

How are lysosomal enzymes produced and activated within the cell?

They are synthesized in the rough endoplasmic reticulum, processed in the Golgi complex, and then released in vesicles. Signup and view all the answers

What role do proteasomes play in post-translational regulation of proteins?

They degrade proteins that are damaged or no longer needed by the cell. Signup and view all the answers

What is a common clinical application of protease inhibitors?

They are employed in the treatment of infections like HIV and Hepatitis C. Signup and view all the answers

Study Notes

Regulation of Gene Expression

Gene expression is the control over the amount of protein being expressed from DNA via transcription and translation.
Constitutive gene expression is constant expression of genes like housekeeping genes needed for cell viability.
Regulated gene expression involves changes in protein levels in response to molecular signals.
- Inducible genes increase protein concentration under specific conditions.
- Repressible genes decrease protein concentration in response to a signal.

Regulation of Gene Expression Levels

Gene regulation can occur at the chromatin level:
- Chromatin remodeling involves the modification of histone proteins, which affects DNA accessibility and subsequently protein expression. Acetylation, phosphorylation of histones increase the negative charge decreasing the strength of DNA interaction with histone decreasing the strength of their association with negatively charged DNA relaxing the nucleosome.
Gene regulation can occur at the DNA level:
- Gene copy number: Increased copies (amplification) lead to increased protein production. (Example: DHFR for thymidine production). Gene deletion leads to reduced production. (Example: RBC maturation and globin chains)
- DNA rearrangement: Various segments rearrange to form different products. (Example: immunoglobulins).

Regulation of Gene Expression: Transcription

Basal expression elements: These elements (e.g., TATA box, CAAT box, GC box) are sequences in DNA that provide locations and frequency for RNA polymerase II initiation.
Regulated expression elements (cis-acting elements): These sequences are on the same gene, and can regulate transcription even when far from the promoter.
- Enhancers: Increase transcription rate.
- Silencers: Decrease transcription rate.

Regulation of Gene Expression: Transcription Complex

Activator proteins: Bind to DNA at enhancer sequences increasing transcription rates.
Repressors: Inhibit binding of transcription factors, decreasing transcription rates.

Regulation of Gene Expression: Post-transcriptional Regulation

Alternative splicing and polyadenylation: Different protein forms from one gene can be produced by selecting different splicing sites.
RNA editing: Single nucleotide changes alter the resultant mRNA. (For instance, different Apoproteins in liver and intestinal cells).
mRNA stability: mRNA stability alters protein quantities. Developmental, environmental, nutrient levels, stress, hormones, and cytokines can affect stability.
Translation regulation: Control over the initiation of protein synthesis.
Post-translational regulation: Proteins can be degraded or modified post synthesis affecting levels.

Clinical Implications of Gene Regulation

Drugs can affect gene expression by inducing DNA methylation or histone modification.
Gene expression dysregulation associated with factors such as cancer, inflammatory diseases, and several myopathies .

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Description

Test your knowledge on the regulation of gene expression, focusing on concepts like constitutive and regulated gene expression, as well as chromatin remodeling. This quiz explores the mechanisms that control protein levels and the role of various molecular signals. Dive into the details of how genes are expressed in different conditions.