Non coding RNAs

What are noncoding RNAs?

Noncoding RNAs are any RNA that does not code for a protein and is not translated into a protein.

What is the function of transfer RNA (tRNA) in protein translation?

tRNA serves as an adapter molecule that reads nucleotide codons in mRNA and inserts the appropriate amino acid into the growing polypeptide chain.

What structure is formed by tRNA due to internal base pairing?

The tRNA folds into a cloverleaf structure with four arms.

What is the role of the anticodon in tRNA?

The anticodon forms complementary base pairs with the codon in mRNA.

What is the function of tRNA synthetases?

tRNA synthetases are enzymes that covalently attach the appropriate amino acid to its corresponding tRNA.

What are ribosomal RNAs (rRNAs) and why are they important?

Ribosomal RNAs are noncoding RNAs that are the most abundant RNA in living organisms and play a crucial role in the formation of ribosomes for protein translation.

How is ribosomal RNA structured in prokaryotes compared to eukaryotes?

In prokaryotes, the large subunit consists of 23S and 5S rRNA; while in eukaryotes, it includes 28S, 5S, and 5.8S rRNA.

What is RNA interference (RNAi)?

RNAi is a phenomenon where RNA molecules inhibit gene expression by binding to complementary mRNA, preventing protein translation.

What effect did overexpressing the chalcone synthase gene in petunias have?

It caused white patches instead of a deeper purple color, indicating suppression of both the transgene and the endogenous gene.

What is the significance of Craig Mello and Andrew Fire in the study of RNA interference?

They discovered the RNA interference pathway and demonstrated its mechanism using C. elegans, for which they won a Nobel Prize.

What are the two types of RNA molecules that elicit RNA interference?

Short interfering RNA (siRNA) and microRNA (miRNA).

What is the role of Dicer in RNA interference?

Dicer processes long double-stranded RNA into short double-stranded RNA fragments, which are involved in the RNAi pathway.

What is the role of the RISC complex in RNA interference?

RISC (RNA-induced silencing complex) incorporates short RNA and facilitates the degradation or translational inhibition of complementary mRNA.

How do microRNAs typically interact with their target mRNAs?

MicroRNAs usually have partial complementarity with target mRNAs, leading to translational inhibition or degradation.

How is RNA interference used in molecular biology?

It is used to manipulate gene expression by knocking down specific genes post-transcriptionally without altering the genome.

What are the two pathways of post-transcriptional processing, and how do they differ?

The two pathways are exogenous, which involves external RNA (like siRNA) introduced to modulate gene expression (used in viral infections), and endogenous, which involves RNA produced within the cell.

What is Dicer and its role in RNA interference?

Dicer is an enzyme that processes long double-stranded RNA into short double-stranded RNA fragments, which are essential components in the RNA interference pathway.

What is the RISC complex and its function in RNA interference?

The RISC (RNA-induced silencing complex) is a multi-protein complex that incorporates small RNA molecules and guides those RNAs to complementary mRNA targets, facilitating mRNA degradation or inhibiting translation.

What molecules do RNA interference (RNAi) and Cas9 target?

RNA interference targets complementary mRNA molecules to inhibit gene expression, while Cas9 targets DNA sequences to create double-strand breaks, leading to gene knockout or modification.

What happens to molecules when they are targeted by RNA interference (RNAi) or Cas9?

When mRNA is targeted by RNAi, it undergoes degradation or translational inhibition. Meanwhile, when DNA sequences are targeted by Cas9, double-strand breaks are created, leading to gene knockout or modification.

How does targeting mRNA lead to gene expression knockdown?

Targeting mRNA with RNA interference (RNAi) leads to knockdown by degrading the mRNA, resulting in a reduction of protein production without eliminating the gene itself.

How does targeting DNA lead to gene knockout?

Targeting DNA with methods like Cas9 results in gene knockout by creating double-strand breaks, which can lead to gene deletion and completely abolish protein production.