T.14 mRNA

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Questions and Answers

What is the primary function of RNA polymerase during transcription?

To translate the RNA sequence into a polypeptide chain
To polyadenylate the 3' end of the RNA
To add a cap to the 5' end of the RNA
To read the DNA template and match incoming nucleotides (correct)

What is the primary function of the cap structure at the 5' end of the RNA?

To stabilize the RNA and prevent degradation
To recruit ribosomes for translation
To enhance translation efficiency
All of the above (correct)

What is the purpose of polyadenylation?

To stabilize the RNA and enhance translation efficiency (correct)
To add a cap to the 5' end of the RNA
To transcribe the DNA template into an RNA molecule
To initiate translation by binding ribosomes to the mRNA

What is the first step in the translation process?

Initiation: Ribosome binds to the mRNA and reads the start codon (C) Signup and view all the answers

What is the role of the ribosome in the translation process?

To bind to the mRNA and read the codons (D) Signup and view all the answers

What is the final product of the translation process?

A polypeptide chain (C) Signup and view all the answers

What is the result of the desamination of adenines in tRNA?

A change in the identity of the base. (C) Signup and view all the answers

What is the function of the snoRNP C/D in archaea?

Guiding the methylation of a nucleotide in each site. (D) Signup and view all the answers

What is the role of Nop5, Nop56, and Nop58 proteins in the snoRNP C/D?

Recognizing the C and C' D and D' boxes. (A) Signup and view all the answers

What is the function of fibrillarin (Fib) in the snoRNP C/D?

Interacting with the D and D' boxes. (D) Signup and view all the answers

What is the structure of the snoRNP H/ACA?

A pseudosymmetric architecture. (D) Signup and view all the answers

What is the role of Cbf5 in the snoRNP H/ACA?

Positioning the pseudouridylation pocket. (D) Signup and view all the answers

What is the proposed structure of the snoRNP H/ACA?

A bipartite structure with a copy of the H/ACA protein core assembled on each hairpin motif of the snoRNA (B) Signup and view all the answers

What is the term used to describe the correction of RNA sequences?

Editing (B) Signup and view all the answers

What is the result of desaminating the citosine in the triplete CAA?

A triplete UAA that causes a premature stop (D) Signup and view all the answers

What type of modification can occur in the RNA sequence of some organisms?

All of the above (D) Signup and view all the answers

What is the consequence of desaminating the citosine in the triplete CAA?

A premature stop in the protein sequence (B) Signup and view all the answers

What is the role of the citidina-desaminasa and adenosina desaminasa enzymes?

To modify the RNA sequence through deamination (C) Signup and view all the answers

What is the consequence of a deficiency or hyperactivity in the adenosina desaminasa enzyme?

Various human diseases, such as epilepsy, cancer, and depression (D) Signup and view all the answers

Where are the majority of the targets of RNA editing found in invertebrates and vertebrates?

In the nervous system (D) Signup and view all the answers

What is the current understanding of the biofisical and physiological changes caused by A to I editing in invertebrates and vertebrates?

The changes are almost completely unknown (A) Signup and view all the answers

What is the difference between the RNA editing process in invertebrates and vertebrates?

The RNA editing process is completely different in invertebrates and vertebrates (C) Signup and view all the answers

What is the main reason why multiple proteins can be obtained from a single gene?

Post-transcriptional modifications of mRNAs (B) Signup and view all the answers

What is the consequence of desamination of a C to a U in a codon CAA in the intestine?

The protein is truncated and lacks 2410 amino acids (A) Signup and view all the answers

What is the purpose of writers and erasers in post-transcriptional modifications of mRNAs?

To methylate adenines in specific positions (A) Signup and view all the answers

What is the effect of methylation in position 1 of adenine on hydrogen bonding?

It introduces a positive charge that blocks hydrogen bonding (D) Signup and view all the answers

What determines the fate of a messenger RNA in the cytoplasm?

The degree and position of methylation (D) Signup and view all the answers

What is the consequence of having multiple forms of apolipoprotein in different tissues?

The protein has different functions in different tissues (C) Signup and view all the answers

What is the role of readers in post-transcriptional modifications of mRNAs?

To determine the functionality of the modification (D) Signup and view all the answers

What is the main difference between the apolipoprotein in the liver and intestine?

The protein is truncated in the intestine (D) Signup and view all the answers

What is the effect of methylation in position 6 of adenine on hydrogen bonding?

It has no effect on hydrogen bonding (C) Signup and view all the answers

What is the purpose of metylations in the life of messenger RNAs?

To influence the life of messengers (B) Signup and view all the answers

What is the primary role of metilations in mRNA?

To serve as a signal for protein binding, affecting translation and degradation (A) Signup and view all the answers

What is the term used to describe the set of modifications in mRNA?

Epitranscriptomics (D) Signup and view all the answers

What is the purpose of the co-transcriptional addition of metilations to mRNA?

To create a specific imprint that conditions the mRNA's fate in the cytoplasm (A) Signup and view all the answers

What is the fate of mRNA molecules that are not translated into protein?

They are stored in cytoplasmic organelles called P-bodies or stress granules (A) Signup and view all the answers

What is the function of the proteins that recognize metilations in mRNA?

To alter the stability or translatability of the mRNA (D) Signup and view all the answers

Why are most metilations in mRNA found outside of the reading frame?

Because they do not have a direct consequence on base pairing (B) Signup and view all the answers

What is the result of having different patterns of metilations in mRNA molecules?

mRNA molecules with different patterns of metilations have different fates in the cytoplasm (D) Signup and view all the answers

What is the role of metiltransferases in the epitranscriptomics process?

To add metilations to mRNA molecules during transcription (A) Signup and view all the answers

What is the main difference between DNA replication and epitranscriptomics?

DNA replication replicates the sequence, while epitranscriptomics introduces modifications (D) Signup and view all the answers

What is the relationship between the pattern of metilations and the translation of mRNA into protein?

The pattern of metilations can make mRNA molecules more or less translatable (D) Signup and view all the answers

Study Notes

mRNA Structure and Synthesis

Transcription

Process of creating a complementary RNA copy from a DNA template
Initiated when an enzyme called RNA polymerase binds to the DNA template
RNA polymerase reads the DNA template and matches the incoming nucleotides to the base pairing rules (A-T, G-C)
The resulting RNA molecule is complementary to the DNA template

Capping

Addition of a specialized structure called a cap to the 5' end of the newly synthesized RNA
The cap is composed of 7-methylguanosine (m7G) and is attached to the first nucleotide of the RNA
Functions:
- Protects the RNA from degradation
- Helps to recruit ribosomes for translation
- Enhances translation efficiency

Polyadenylation

Process of adding a long string of adenine nucleotides (poly(A) tail) to the 3' end of the RNA
Occurs after transcription is complete
Functions:
- Stabilizes the RNA and prevents degradation
- Enhances translation efficiency
- Helps to transport the RNA out of the nucleus

Translation

Process of using the mRNA sequence to build a polypeptide chain
Occurs in the cytoplasm
Steps:
1. Initiation: Ribosome binds to the mRNA and reads the start codon
2. Elongation: Amino acids are brought to the ribosome and added to the growing polypeptide chain
3. Termination: The ribosome reaches the stop codon and releases the completed polypeptide chain

Splicing

Process of removing introns (non-coding regions) and joining exons (coding regions) to form a mature RNA
Occurs in the nucleus
Steps:
1. Recognition: Spliceosomes recognize the intron-exon boundaries
2. Cleavage: The intron is cleaved from the RNA
3. Ligation: The exons are joined together to form a mature RNA

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Description

This quiz covers the process of creating a complementary RNA copy from a DNA template, including transcription, capping, polyadenylation, translation, and splicing. Learn about the functions of each step and how they contribute to the formation of a mature RNA.