mRNA Modification and Structure
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Questions and Answers

What is the role of the spliceosome?

  • To aid in the synthesis of proteins
  • To remove introns from the mRNA (correct)
  • To add a G-Cap to the mRNA
  • To enhance the translation of mRNA

Exons are segments of RNA that are not translated into proteins.

False (B)

What is added to the 5' end of mRNA to assist with ribosome binding?

G-Cap

The small nuclear _______ (abbreviation) are involved in recognizing and removing intron sequences.

<p>snRNPs</p> Signup and view all the answers

Match the following terms with their descriptions:

<p>Introns = Nucleotide sequences removed during splicing Exons = Nucleotide sequences expressed in proteins Alternative Splicing = Creation of different mRNA strands from the same gene Poly-A Tail = Sequence added to the 3' end of mRNA for protection</p> Signup and view all the answers

What is the significance of alternative splicing?

<p>It allows a single gene to code for multiple proteins (C)</p> Signup and view all the answers

The Poly-A tail consists of 50-300 dATP nucleotides.

<p>True (A)</p> Signup and view all the answers

What is the primary function of the Poly-A tail in mRNA?

<p>To protect mRNA from enzymatic digestion</p> Signup and view all the answers

Flashcards

mRNA Splicing

The process of removing non-coding sequences (introns) from pre-mRNA, leaving only the coding sequences (exons) to be translated into proteins.

Introns

Non-coding sequences within pre-mRNA that are removed during splicing. They are not translated into proteins.

Exons

Coding sequences within pre-mRNA that are kept after splicing and used to create proteins. They contain the genetic code for the amino acid sequence.

Spliceosome

A large complex molecular machine that removes introns from pre-mRNA during splicing. It is made up of snRNAs and proteins.

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snRNPs

Small nuclear ribonucleoproteins involved in splicing. They recognize intron sequences, remove them, and ligate exons together.

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Alternative Splicing

A process where different exons can be spliced out from a single pre-mRNA molecule, resulting in multiple protein isoforms from one gene.

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G-Cap

A modified guanine nucleotide attached to the 5' end of mRNA. It protects the mRNA from degradation and helps the mRNA bind to the ribosome.

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Poly-A Tail

A series of adenine nucleotides added to the 3' end of mRNA. It protects the mRNA from enzymatic degradation and helps the mRNA exit the nucleus.

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Study Notes

mRNA Modification

  • mRNA must be modified before leaving the nucleus
  • Introns are removed, leaving only exons
  • Small nuclear ribonucleoproteins (snRNPs) are crucial in this process:
    • They cut out introns and join exons together
  • Alternative splicing allows for different exon combinations, resulting in diverse protein products from a single gene
  • A 5' cap (G-Cap) is added to the 5' end of the mRNA to facilitate ribosome binding
  • A poly-A tail (50-300 adenine nucleotides) is added to the 3' end for protection from degradation
  • Mature mRNA, containing only exons, the cap, and the tail, exits the nucleus to the cytoplasm

Mature mRNA

  • Mature mRNA comprises only of exons, a 5' G-cap, and a 3' poly-A tail
  • Mature mRNA leaves the nucleus and enters the cytoplasm, ready for translation
  • Untranslated regions (UTRs) are present on both 5' and 3' ends, and these do not code for a protein sequence.

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Description

This quiz explores the essential processes involved in mRNA modification. It covers key concepts such as intron removal, the role of snRNPs, alternative splicing, and the addition of the 5' cap and 3' poly-A tail. Understand how mature mRNA is formed and prepared for translation in the cytoplasm.

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