Non-coding RNAs Overview

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Questions and Answers

Which of the following complexes are involved in chromatin remodeling?

Histone deacetylase inhibitors

Polycomb complexes (correct)

DNA methylation binding proteins

SWI/SNF1 complexes (correct)

What is the primary focus of Unit 2 in small RNA biology and epigenetics?

Microbial cross-talk

Characterization of histone modifications

Study of chromatin modifiers

Interpretation of DNA methylation marks (correct)

Which enzyme class is studied in connection with histone modifications?

Histone methyltransferases

Drone enzymes

Cyclin-dependent kinases

Histone deacetylases (correct)

How do small RNAs affect gene expression?

Via transcriptional gene silencing and post-transcriptional regulation Signup and view all the answers

What role do small non-coding RNAs have in biotechnology?

They are effective tools in gene silencing and gene editing Signup and view all the answers

Which factor is discussed in Unit 5 regarding the impact on epigenetics?

Environmental stressors Signup and view all the answers

Which process is NOT associated with the regulation of gene expression by small RNAs?

Functional translation of proteins Signup and view all the answers

What is the significance of small RNA pathways in biological systems?

They regulate biological processes in various organisms Signup and view all the answers

What is the Svedberg coefficient of the small subunit rRNA in prokaryotes?

16S Signup and view all the answers

Which rRNA molecule is likely to have the largest size in eukaryotic ribosomes?

28S Signup and view all the answers

What is the primary function of ribosomal RNA in protein synthesis?

Translating mRNA into amino acids Signup and view all the answers

Which site in the ribosome is known as the peptidyl site?

P site Signup and view all the answers

How does the rRNA sequence contribute to studies of evolutionary relationships?

It shows high conservation in core catalytic sites. Signup and view all the answers

What does the 16S rRNA serve as in molecular studies?

Taxonomic genomic marker for bacteria and archaea Signup and view all the answers

In which location do eukaryotes contain additional rRNA besides the ribosomes?

Mitochondria and chloroplasts Signup and view all the answers

Which of the following is NOT a feature of ribosomal RNA?

Acts as a template for protein synthesis Signup and view all the answers

What is a primary reason for the design of novel antibiotics?

Research showing antibiotic-binding sites on the ribosomal subunit. Signup and view all the answers

How do point mutations contribute to antibiotic resistance in bacteria?

They alter binding sites on ribosomal RNA. Signup and view all the answers

Which type of RNA is implicated in inflammation and cardiac disease as a result of mechanical stress?

Micro RNA (miRNA) Signup and view all the answers

What sequence is encoded by the 45S gene identified in murine pre-ribosomal RNA?

18S, 5.8S, and 28S rRNA sequences. Signup and view all the answers

Which bacterial genus exhibits resistance to Spectinomycin due to mutations in rRNA?

Streptomyces Signup and view all the answers

What is the primary role of ribosomal RNAs (rRNAs) in cells?

To serve as a binding site for ribosomal proteins Signup and view all the answers

Which type of non-coding RNAs is characterized by their abundance and ubiquity in expression?

Housekeeping non-coding RNAs Signup and view all the answers

What size range do housekeeping non-coding RNAs typically fall into?

50 to 500 nucleotides Signup and view all the answers

What is the main function of transfer RNA (tRNA) in the ribosome?

To bring amino acids to the ribosome for protein synthesis Signup and view all the answers

What key process do ribosomes facilitate in cells?

Translation of mRNA into proteins Signup and view all the answers

How were ribosomal RNAs (rRNAs) initially discovered?

During cell fractionation experiments Signup and view all the answers

What characteristic feature distinguishes housekeeping non-coding RNAs from other types of non-coding RNAs?

They are essential for survival and cell viability. Signup and view all the answers

Which process is NOT associated with non-coding RNAs?

Direct translation into proteins Signup and view all the answers

What primarily allows examination of genetic diversity in microbial communities?

16S rRNA analysis Signup and view all the answers

What significant feature do the 16S and 23S rRNAs share?

They show a high degree of sequence identity. Signup and view all the answers

What causes differences in ribosomal RNA sequences among species?

Mutation in encoding genes Signup and view all the answers

Why is ribosomal RNA function highly conserved across species?

It is essential for cellular functions. Signup and view all the answers

How can rRNA sequences assist in understanding evolutionary relationships?

By distinguishing organisms at the species level Signup and view all the answers

What distinguishes the molecular structure of ribosomes between different organisms?

Subtle sequence differences due to mutations Signup and view all the answers

What role does rRNA play in preparing antibacterial treatments?

It serves as a target for small molecules. Signup and view all the answers

Which statements about the evolutionary changes in ribosomal RNA are correct?

They accumulate slowly without significantly altering structure. Signup and view all the answers

Study Notes

Non-coding RNAs

ncRNAs are functional RNA molecules transcribed from DNA that are not translated into proteins.

Housekeeping Non-coding RNAs

Housekeeping ncRNAs are ubiquitously expressed and regulate basic cellular functions.
They include rRNAs, tRNAs, snRNAs, snoRNAs, and TERC.
They are typically small, ranging from 50 to 500 nucleotides long (except rRNAs).
They are constitutively expressed in all cell types.
They are essential for cell viability.

Ribosomal RNAs (rRNAs)

rRNAs are the most abundant class of RNA in most cells, making up approximately 80% of the cellular transcriptome.
Ribosomes are ribonucleoprotein complexes responsible for protein synthesis in all life forms.
rRNAs are the essential binding site for ribosomal proteins and contribute to the binding of extra-ribosomal factors and ribosome-associated proteins.
rRNAs were discovered through cell fractionation and are identified by their sedimentation rate (Svedberg coefficient).

Ribosomal Subunits

Prokaryotes have a 30S small subunit with a 16S rRNA (~1500 nt) and a 50S large subunit with 23S rRNA (~2900 nt) and 5S rRNA (~120 nt).
Eukaryotes have a 40S small subunit with 18S rRNA (~2 kb) and a 60S large subunit with 28S rRNA (~5 kb), 5.8S rRNA (~200 nt), and 5S rRNA (~200 nt).
Eukaryotic cells also contain rRNA in mitochondria and chloroplasts.

Importance of rRNAs

Protein Translation: rRNAs bind to mRNA and tRNA ensuring accurate translation of codons into amino acid sequences.
Evolutionary and Diversity Studies: rRNAs are highly conserved, making them excellent tools for studying taxonomy and phylogenetics.
Targets of Antibiotics: rRNA is a commonly exploited target for antibiotics. The difference between prokaryotic and eukaryotic rRNA allows for targeting pathogenic bacteria.
Regulatory RNAs from rRNAs: Pre-ribosomal RNA has been implicated in generating microRNAs involved in inflammation and cardiac disease.

Small Nuclear RNAs (snRNAs)

snRNAs are small RNA molecules involved in splicing, a crucial step in gene expression.
snRNAs associate with proteins to form snRNPs (small nuclear ribonucleoproteins).
snRNPs participate in the spliceosome, a complex responsible for removing introns from pre-mRNA and joining exons to form mature mRNA.
snRNAs have specific sequences that recognize and bind to specific regions of pre-mRNA, facilitating the splicing process.
snRNAs play a vital role in ensuring the accuracy and efficiency of gene expression.

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Description

This quiz explores the various types of non-coding RNAs, focusing on housekeeping non-coding RNAs like rRNAs and tRNAs. Understand their functions, importance in cellular processes, and their role in protein synthesis. Test your knowledge on these crucial RNA molecules essential for cell viability.