Non-Coding Regulatory RNAs and Gene Regulation

30 flashcards covering key concepts about non-coding regulatory RNAs and gene regulation as discussed in lectures.

What is dosage compensation?

It ensures that female cells and male cells express the same amount of proteins encoded by X chromosome genes.

How do mammal females achieve dosage compensation?

By inactivating one of the two X chromosomes.

What would happen if both X chromosomes were expressed in females?

It would create a large imbalance of proteins, leading to instability in protein complexes.

What is the significance of X-inactivation in calico cats?

It results from random X chromosome inactivation in females that are heterozygous for black and brown alleles.

What role does Xist long non-coding RNA play in X-inactivation?

Xist mRNA coats the X chromosome and triggers its silencing.

How is dosage compensation achieved in Drosophila?

Through the MSL complex, which includes the roX RNA.

What are small regulatory RNAs in eukaryotes?

They include small interference RNAs (siRNAs), micro RNAs (miRNAs), and Piwi RNAs (piRNAs).

What is a riboswitch?

A segment of RNA that can change its structure in response to a ligand, affecting gene expression.

What does the SAM-sensing riboswitch regulate?

Genes involved in methionine or cysteine biosynthesis.

What is the function of piwiRNAs?

They protect the germ line against transposable element activity.

How does the CRISPR system provide immunity to bacteria?

By integrating foreign DNA fragments into the CRISPR locus for recognition during future infections.

What is the role of Cas genes in the CRISPR system?

They provide an adaptive immune system to bacteria.

What are proto-spacer adjacent motifs (PAM)?

Conserved sequences that help Cas enzymes recognize target DNA for cleavage.

What are the two goals of CRISPR technology?

Induce mutations and introduce donor DNA for homologous repair.

What is the implication of splicing defects in hereditary diseases?

13.4% of hereditary disease alleles are classified as splicing mutations.

What are the three classes of RNA splicing?

Nuclear pre-mRNA, group II introns, and group I introns.

What constitutes a spliceosome?

A macromolecular machine consisting of snRNAs and proteins.

What are exonic splicing enhancers (ESEs)?

They are sequences that help recruit splicing machinery for proper splicing.

What is alternative splicing?

A process where a single gene can produce multiple mRNA variants by including or excluding certain exons.

How does the Sxl gene determine sex in Drosophila?

It acts as a master regulator in the pathway, influencing splicing patterns.

What mechanisms prevent errors during splice-site selection?

Coupling splicing with transcription and using SR proteins.

What are the implications of exon shuffling in eukaryotic genes?

It allows evolutionary diversity by mixing domains encoded by exons.

What does RNA editing involve?

It involves changing the identity of an RNA base after transcription.

What is the function of ADAR?

Adenosine deaminase acting on RNA, involved in RNA editing.

What happens to cytosine deaminated during RNA editing?

It produces uracil, allowing for specific pairing with adenine.

What is the typical function of enhancers in regulation?

They induce splicing by aiding the binding of splicing machinery.

What is the impact of silencer proteins on splicing?

They repress splicing by preventing the splicing machinery from binding.

What is the consequence of nonsense mediated decay (NMD)?

It flags RNA for degradation when unexpected stop codons are present.

What is mutually exclusive splicing?

It refers to exons that cannot be included together in an mRNA transcript.

What are the splicing mechanisms for group II introns?

They undergo the same transesterification reactions as pre-mRNA splicing.

What is a key feature of alternative splicing in human genes?

At least ~15% of mutations affecting genetic diseases are linked to splicing defects.

What is the significance of the titin gene?

It has the largest number of exons in human genes, highlighting complexity in splicing.

What is the expected effect of intron retention during splicing?

It can lead to the production of nonfunctional proteins.

What is the role of branched lariat structures in splicing?

They are intermediates formed during the splicing process, resulting from two transesterification reactions.