micro 10.3 pt 3

What is heterogeneous nuclear RNA (hnRNA)?

The initial RNA transcript produced in eukaryotic cells before it is processed into mature mRNA.

What are exons?

Coding regions of a gene that remain in the mature mRNA after RNA processing.

What are introns?

Noncoding regions that are removed from hnRNA during RNA processing.

What process removes introns from hnRNA?

RNA splicing.

What enzyme complex carries out RNA splicing?

The spliceosome.

What is added to the 5′ end of eukaryotic mRNA during processing?

A 5′ cap.

What is the function of the 5′ cap?

It protects mRNA from degradation and helps the ribosome recognize the mRNA for translation.

What is added to the 3′ end of eukaryotic mRNA during processing?

A poly-A tail.

What is the function of the poly-A tail?

It increases mRNA stability, protects it from degradation, and aids in export from the nucleus.

Do prokaryotic mRNAs undergo extensive processing like eukaryotic mRNAs?

No. Most prokaryotic mRNAs are translated soon after transcription with little or no processing.

Where does mRNA processing occur in eukaryotic cells?

In the nucleus.

Where does mature mRNA go after processing?

It leaves the nucleus and enters the cytoplasm for translation.

Why is mRNA processing important?

It produces a stable, functional mRNA that can be translated into protein.

Which type of RNA is directly translated into protein?

Messenger RNA (mRNA).

Which type of RNA recognizes mRNA codons during translation?

Transfer RNA (tRNA).

Which type of RNA forms the catalytic core of the ribosome?

Ribosomal RNA (rRNA).

Which RNA molecule links DNA to protein synthesis?

Messenger RNA (mRNA).

Why can a single gene produce different proteins in eukaryotes?

Because alternative RNA splicing can combine exons in different ways.

What is alternative RNA splicing?

The production of different mature mRNAs from the same hnRNA by joining exons in different combinations.

What is the advantage of alternative RNA splicing?

It allows one gene to produce multiple protein products.

Which type of cell contains hnRNA?

Eukaryotic cells.

Why are introns removed before translation?

Because introns are noncoding sequences and are not translated into protein.

What remains after RNA splicing?

Exons joined together to form mature mRNA.

What protects eukaryotic mRNA from rapid degradation?

The 5′ cap and the poly-A tail.

Which RNA processing step occurs first: splicing, 5′ capping, or polyadenylation?

The 5′ cap is added first, followed by splicing and polyadenylation.

Why is mature mRNA required before translation in eukaryotes?

It must be properly processed so the ribosome can accurately translate it.

How does RNA differ from DNA in function?

RNA primarily participates in gene expression, whereas DNA serves as the long-term storage of genetic information.

What is the primary purpose of RNA processing?

To convert the primary RNA transcript into a functional mature mRNA.

Why is RNA essential for protein synthesis?

It carries genetic information, brings amino acids to the ribosome, and catalyzes peptide bond formation.

What is the central concept of RNA structure and function?

RNA is a versatile nucleic acid that carries, processes, regulates, and translates genetic information into proteins.