T.14 Tipos de procesamiento del RNA / RNPs en la célula eucariota

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary function of ribonucleoproteins (RNPs) in eukaryotic cells?

To facilitate the translation of mRNA into protein

To transcribe DNA into RNA

To protect RNA from degradation and facilitate recognition (correct)

To replicate DNA during cell division

What is the significance of the code written in RNA in the form of chemical modifications?

It increases the stability of the RNA

It enhances the transcription rate of RNA

It facilitates the binding of RNA to specific proteins (correct)

It determines the secondary structure of the RNA

What is the purpose of the caperuza structure in RNA transcribed by RNA pol II?

To enhance the stability of the RNA

To protect the RNA from degradation by Rat1 (correct)

To increase the transcription rate of RNA

To facilitate the translation of mRNA into protein

What is the difference between RNPs in eukaryotic and prokaryotic cells?

RNPs play a more important role in eukaryotic cells Signup and view all the answers

What is the function of the spliceosoma in RNA processing?

To remove introns and join exons Signup and view all the answers

What is the primary function of RNA tools?

To utilize the information available in mRNA Signup and view all the answers

In what type of RNA do we observe the formation of RNPs?

In all types of RNA precursors Signup and view all the answers

Which of the following types of RNA do not undergo modifications?

Non-coding RNA Signup and view all the answers

What is the primary difference between procariotas and eucariotas in terms of RNA modification?

The type of modifications that occur Signup and view all the answers

What is the main purpose of classifying RNA modifications?

To understand the function of each RNA Signup and view all the answers

What type of bond is formed between the guanine nucleotide and the first nucleotide of the pre-mRNA?

5'PPP5' bond Signup and view all the answers

What is the function of the metiltransferase enzyme during cap formation?

Addition of a methyl group to the 7-position of guanine Signup and view all the answers

What is the role of the CTD in the formation of the cap structure?

Binding of the enzymes to the RNA nascent chain Signup and view all the answers

What is the purpose of the cap structure in eukaryotic mRNA?

To protect the RNA from degradation Signup and view all the answers

What is the function of the NAD cap in some eukaryotic RNAs?

To serve as a signal for degradation Signup and view all the answers

What is the primary function of TUTases in RNA metabolism?

To mark RNAs for degradation through the addition of poly-U tails Signup and view all the answers

What is the purpose of introducing poly-A tails in mRNAs?

To stabilize them and prevent degradation Signup and view all the answers

Which of the following RNAs does not have a poly-A tail?

Histone mRNAs Signup and view all the answers

What is the function of exonucleases in relation to TUTases?

They degrade RNAs marked with poly-U tails Signup and view all the answers

What is the consequence of forming a poly-U tail after a poly-A tail in some mRNAs?

Degradation of the mRNA Signup and view all the answers

What is the primary function of spliceosomes in RNA processing?

To perform splicing by removing introns and joining exons Signup and view all the answers

What type of RNA editing involves the insertion or deletion of nucleotides?

Insertion/deletion editing Signup and view all the answers

What is the primary function of microRNA in RNA interference?

To bind to target mRNA and prevent translation Signup and view all the answers

What is the consequence of alternative splicing?

Production of different mRNA isoforms Signup and view all the answers

What is the primary function of editases in RNA editing?

To catalyze the deamination of specific nucleotides Signup and view all the answers

What is the purpose of the RNA-induced silencing complex (RISC) in RNA interference?

To recruit small interfering RNA (siRNA) Signup and view all the answers

What is the primary function of splicing factors in RNA processing?

To facilitate alternative splicing Signup and view all the answers

What is the purpose of small interfering RNA (siRNA) in RNA interference?

To guide the degradation of target mRNA Signup and view all the answers

What is the primary function of RNA interference (RNAi)?

To regulate gene expression Signup and view all the answers

What is the consequence of RNA editing?

Regulation of gene expression Signup and view all the answers

What is the primary function of the large 60S subunit in eukaryotic cells?

To contain the 28S rRNA, 5.8S rRNA, and 5S rRNA Signup and view all the answers

What is the role of initiation factors (eIFs) during translation initiation in eukaryotic cells?

To facilitate the recruitment of the large 60S subunit Signup and view all the answers

What is the outcome of the two transesterification reactions catalyzed by the spliceosome?

Formation of a lariat structure and excision of the intron Signup and view all the answers

What is the sequence of events in protein synthesis in eukaryotic cells?

Transcription of DNA to pre-mRNA, splicing, and translation Signup and view all the answers

What is the purpose of capping and polyadenylation during mRNA processing in eukaryotic cells?

To facilitate translation initiation and mRNA stability Signup and view all the answers

Study Notes

Types of RNA Processing

RNA undergoes modification during or after transcription, which is essential for understanding its function
There are three subgroups of RNA:
- RNA that carry information (mRNA)
- RNA tools (tRNA, rRNA, snRNA)
- Non-coding RNA (not studied in detail)

Modifications of RNA

Modifications can be classified by type and in which RNA molecule they occur
Modifications can occur in both prokaryotes and eukaryotes
The table shows modifications of RNA precursors, with the last column added later to show the formation of RNP, which is essential for RNA function

RNPs in Eukaryotic Cells

Ribonucleoproteins (RNPs) are stable associations between proteins and RNA
In eukaryotic cells, RNA is never bare, but associates with proteins to protect it from degradation and for recognition
RNPs are formed in the nucleus before transporting to the cytoplasm
Proteins can exchange with others in the cytosol, resulting in different proteins bound to the RNA

mRNPs in Eukaryotic Nucleus

The association of RNA with proteins provides information about its fate
RNA modifications can be read by proteins, which then bind to the RNA
The code is written in the RNA as chemical modifications, which are read by proteins and specific binding occurs
Readers of the code include degradation machinery, transport machinery, spliceosomes, and translation machinery

Capping of RNA

The cap is a structure that associates exclusively with RNA transcribed by RNA polymerase II
If the cap is not added, the primary transcript is rapidly degraded
The cap is a guanine nucleotide that is "in reverse" and is resistant to degradation
The process of capping involves phosphatases, guanylyltransferases, and methyltransferases

Role of CTD

The enzymes involved in capping are attracted to the CTD tail of RNA polymerase II, which is phosphorylated on serine 5
The binding of enzymes to the CTD tail is important, as it accelerates the reaction rate
The enzymes are released once the serine 2 is phosphorylated

NAD Capping

Recently discovered: NAD capping in mRNAs, where NAD is a dinucleotide (A linked to nicotinamide)
NAD is added to the end of a messenger by a phospho-phospho bond
In prokaryotes, NAD is not added later, but RNA polymerase uses NAD as the first nucleotide instead of ATP
The modification is a signal for the cell to read and degrade the RNA in a specific way

Poly (A) and Poly (U) Tails

Poly (A) tails are found in the other end of transcripts, and are only introduced in messengers (except for histone messengers)
The introduction of poly (A) tails is a mechanism of transcription termination
Poly (U) tails are introduced by the TUTase enzyme, which is a writer that marks RNA for degradation
Poly (U) tails can be introduced in RNA that did not have a tail previously, such as histone mRNAs
The degradation of RNA with poly (U) tails is dependent on uridinilation

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Learn about the different types of RNA processing and modification that occur during or after transcription. Understand the functions of mRNA, tRNA, rRNA, and snRNA, and how they enable the utilization of genetic information. Discover the essential roles of RNA modification in gene expression.