RNA Polymerases and Alternative Splicing
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Questions and Answers

Which RNA polymerase is responsible for transcribing protein-encoding genes in eukaryotes?

  • RNA polymerase III
  • RNA polymerase II (correct)
  • RNA polymerase I
  • RNA polymerase IV

How many RNA polymerases do eukaryotes possess?

  • Two
  • Four
  • Three (correct)
  • One

What type of genes does RNA polymerase I transcribe?

  • 5S rRNA genes
  • rRNA genes (correct)
  • tRNA genes
  • mRNA genes

Which of the following RNA polymerases is NOT found in prokaryotes?

<p>RNA polymerase I (A), RNA polymerase II (B), RNA polymerase III (C)</p> Signup and view all the answers

Which function does RNA polymerase III perform?

<p>Transcribes tRNA genes and 5S rRNA genes (C)</p> Signup and view all the answers

What is the primary outcome of alternative splicing in RNA molecules?

<p>Creation of multiple proteins from the same RNA (B)</p> Signup and view all the answers

Which statement best describes the role of alternative splicing in biological processes?

<p>It enhances the complexity of gene expression. (B)</p> Signup and view all the answers

How does alternative splicing contribute to diagnostics and therapeutics?

<p>It helps identify novel diagnostic and prognostic biomarkers. (A)</p> Signup and view all the answers

What does the diagram of alternative splicing mainly illustrate?

<p>Different proteins arise from varied exon combinations. (B)</p> Signup and view all the answers

In the context of alternative splicing, which describes its significance for organism development?

<p>It plays a vital role in cellular differentiation. (A)</p> Signup and view all the answers

What enzyme is primarily responsible for the synthesis of pre-mRNA during transcription?

<p>RNA polymerase II (A)</p> Signup and view all the answers

During transcription, what is the relationship between the newly formed mRNA and the original DNA sequence?

<p>They have complementary sequences. (D)</p> Signup and view all the answers

What is the process called that modifies pre-mRNA into mature mRNA?

<p>RNA splicing (C)</p> Signup and view all the answers

In the context of gene expression, what role does mRNA play after its formation?

<p>It carries information for protein synthesis. (C)</p> Signup and view all the answers

What represents the primary outcome of the transcription process?

<p>Production of pre-mRNA (D)</p> Signup and view all the answers

What does the codon AUG specify in the process of translation?

<p>Amino acid that signals the start of translation (D)</p> Signup and view all the answers

Which of the following codons is considered a termination codon?

<p>UAA (B)</p> Signup and view all the answers

How are codons structured in mRNA?

<p>Group of three nucleotides (B)</p> Signup and view all the answers

What is the primary function of RNA polymerase during the elongation stage of transcription?

<p>To synthesize a complementary RNA strand using a DNA template (B)</p> Signup and view all the answers

In the codon table, what amino acid is encoded by the codon UUU?

<p>Phenylalanine (B)</p> Signup and view all the answers

What role does the genetic code play in translation?

<p>It determines the sequence of amino acids in a protein (D)</p> Signup and view all the answers

Which base pairing occurs between the DNA template and the RNA during transcription?

<p>A-U and C-G pairing (B)</p> Signup and view all the answers

In which step does RNA polymerase bind to the promoter region of the gene?

<p>Initiation (D)</p> Signup and view all the answers

What happens to the DNA double helix after transcription is complete?

<p>It reforms into its original double helix structure (B)</p> Signup and view all the answers

What signals the termination of transcription in the presence of RNA polymerase?

<p>The encounter with a codon that acts as a stop signal (A)</p> Signup and view all the answers

What role do snRNPs play in the process of mRNA splicing?

<p>They bind to the intron sequence and facilitate its removal. (D)</p> Signup and view all the answers

What structural formation is created from the folding of the intron during splicing?

<p>A lariat loop. (A)</p> Signup and view all the answers

What happens to the exons during mRNA splicing?

<p>They move closer together and join to form the mature mRNA. (C)</p> Signup and view all the answers

What is released as a byproduct of the splicing process?

<p>The intron. (D)</p> Signup and view all the answers

After performing its function in splicing, what can snRNPs do?

<p>Detach and be reused for further splicing events. (C)</p> Signup and view all the answers

What is the primary function of the 5' cap in pre-mRNA processing?

<p>Protects mRNA from degradation (C)</p> Signup and view all the answers

Which of the following accurately describes the role of the 3' poly-A tail?

<p>It protects mRNA from degradation (D)</p> Signup and view all the answers

During pre-mRNA splicing, what is primarily removed from the transcript?

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

How do end modifications affect the stability of mRNA?

<p>They increase the stability of the mRNA (A)</p> Signup and view all the answers

What essential role does splicing play in pre-mRNA processing?

<p>It ensures the correct sequence by removing non-coding regions (C)</p> Signup and view all the answers

What direction does transcription proceed in?

<p>5' – 3' (A)</p> Signup and view all the answers

In which direction is the antisense (template) strand read during transcription?

<p>3' – 5' (B)</p> Signup and view all the answers

Which of the following statements is true about the newly generated RNA strand?

<p>It is complementary to the template strand. (D)</p> Signup and view all the answers

Which end of the RNA strand is extended by RNA polymerase during transcription?

<p>3' end (C)</p> Signup and view all the answers

Which of the following statements accurately describes the relationship between mRNA and the template strand?

<p>mRNA is complementary to the template strand. (B)</p> Signup and view all the answers

Which type of RNA is primarily responsible for carrying information from DNA to ribosomes?

<p>Messenger RNA (mRNA) (B)</p> Signup and view all the answers

What is the main role of transfer RNA (tRNA) in protein synthesis?

<p>Transporting amino acids to the mRNA strand (C)</p> Signup and view all the answers

Which statement accurately describes ribosomal RNA (rRNA)?

<p>It is part of the ribosome and aids in assembling amino acids. (B)</p> Signup and view all the answers

Which of the following describes the structure of transfer RNA (tRNA)?

<p>A three-legged structure with colored attachments (C)</p> Signup and view all the answers

What role does messenger RNA (mRNA) play in the process of protein synthesis?

<p>It acts as a template for assembling a sequence of amino acids. (C)</p> Signup and view all the answers

Which of the following accurately describes a key difference between DNA and RNA?

<p>The sugar in DNA is deoxyribose, whereas RNA contains ribose. (B)</p> Signup and view all the answers

Which nitrogenous base is unique to RNA as compared to DNA?

<p>Uracil (C)</p> Signup and view all the answers

What is the primary structural characteristic of RNA that distinguishes it from DNA?

<p>RNA is usually single-stranded. (D)</p> Signup and view all the answers

Which statement best summarizes the functional relationship between DNA and RNA?

<p>RNA synthesizes proteins using the information encoded in DNA. (C)</p> Signup and view all the answers

How do the sugars of RNA and DNA differ structurally?

<p>RNA has a carbon atom at position 2 that is absent in DNA. (D)</p> Signup and view all the answers

Flashcards

Prokaryotic RNA Polymerase

In prokaryotic cells, there is only one type of RNA polymerase responsible for transcribing all types of RNA.

Eukaryotic RNA Polymerases

In eukaryotic cells, there are three distinct RNA polymerases, each with a specific role in transcription.

RNA Polymerase I

RNA polymerase I is responsible for transcribing ribosomal RNA (rRNA) genes, which are essential for protein synthesis.

RNA Polymerase II

RNA polymerase II transcribes protein-coding genes, which are the blueprints for proteins.

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RNA Polymerase III

RNA polymerase III transcribes transfer RNA (tRNA) genes and the 5S ribosomal RNA gene.

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Transcription

The process of copying genetic information from DNA to mRNA.

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Messenger RNA (mRNA)

A type of RNA that carries the genetic code from DNA to the ribosomes for protein synthesis.

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Pre-mRNA

The initial RNA molecule produced during transcription, which is subsequently processed to become mature mRNA.

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RNA splicing

The process of removing non-coding regions (introns) from pre-mRNA to create mature mRNA.

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Alternative splicing

A process where a single RNA molecule can create different proteins by combining different sections of its exons.

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Protein diversity

Alternative splicing allows one gene to generate multiple proteins, increasing the diversity of proteins produced in an organism.

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Gene expression complexity

The ability to create a vast array of protein combinations through alternative splicing contributes to the complexity of how genes are expressed.

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Cellular differentiation and development

Alternative splicing plays a crucial role in the development of different cell types (differentiation) and the overall growth and development of an organism.

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Implications for diagnostics and therapeutics

Research on alternative splicing has led to the identification of potential diagnostic and prognostic biomarkers, and it offers promising avenues for developing new cancer therapies.

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What is a Codon?

Three consecutive nucleotide bases in mRNA that code for a specific amino acid.

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What is the role of AUG?

Special codons that signal the start of protein synthesis; code for the amino acid methionine.

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What is the role of UAA, UAG, and UGA?

Codons that signal the end of protein synthesis.

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What is translation?

Translation is process of converting genetic code in mRNA to amino acid sequence to build a protein.

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What is a Codon Table?

A table that shows the relationship between mRNA codons and the amino acids they encode.

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What happens during initiation of transcription?

RNA polymerase attaches to a specific region on the DNA called the promoter, which initiates the unwinding of the DNA double helix.

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What is the purpose of elongation during transcription?

RNA polymerase uses one strand of DNA as a template to create a complementary RNA molecule.

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What happens during termination of transcription?

RNA polymerase recognizes a stop signal in the DNA sequence, causing transcription to end.

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What is the role of RNA polymerase in transcription?

RNA polymerase is an enzyme crucial for the synthesis of RNA, acting as a molecular machine that copies the genetic information from DNA into RNA during the process of transcription.

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How does RNA polymerase build the RNA molecule?

RNA polymerase reads the DNA sequence and builds a complementary RNA molecule, using the base pairing rules (A-U, G-C).

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What does mRNA do?

Messenger RNA (mRNA) carries the genetic code from DNA to ribosomes, where proteins are made.

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What does tRNA do?

Transfer RNA (tRNA) brings specific amino acids to the ribosome, matching them to the mRNA's code to build the protein.

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What is rRNA's role in protein synthesis?

Ribosomal RNA (rRNA) is a structural component of ribosomes, the protein factories.

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How do the three types of RNA collaborate?

The three types of RNA work together to translate the genetic code from DNA into proteins: mRNA delivers the message, tRNA brings the building blocks, and rRNA provides the structure.

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How is mRNA represented?

Messenger RNA (mRNA) is like a blueprint; it's a ribbon-like structure with instructions written on it.

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5' cap

A protective cap added to the 5' end of pre-mRNA, preventing degradation and aiding in translation initiation.

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3' poly-A tail

A series of adenine nucleotides added to the 3' end of pre-mRNA, increasing stability and signaling export to the cytoplasm.

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Pre-mRNA splicing

The process of removing introns from pre-mRNA, ensuring only coding regions (exons) remain for protein synthesis.

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End modifications

Modifications that increase the stability of mRNA by protecting against degradation and aiding in translation initiation.

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What is the purpose of splicing?

The removal of introns from pre-mRNA, resulting in a mature mRNA sequence ready for protein synthesis.

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What is a spliceosome?

A large complex of proteins and RNA molecules that removes introns from pre-mRNA. It binds to intron sequences, causing the intron to fold into a loop structure called a lariat.

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What are snRNPs?

Small nuclear ribonucleoproteins (snRNPs) are key components of the spliceosome. These are RNA-protein complexes that recognize and bind to specific sequences within introns. They help in the folding and removal of introns during RNA splicing.

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What is a lariat?

A loop structure formed when the 5' and 3' ends of an intron are brought together by the spliceosome. This loop structure helps in the removal of the intron.

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What are introns?

Non-coding regions within a gene that are removed from pre-mRNA during splicing. They are found between exons (coding regions).

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What are exons?

Coding regions within a gene that are joined together after splicing. They contain the genetic information that is translated into proteins.

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Template strand

The strand of DNA that is used as a template for the synthesis of RNA.

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Non-template strand

The strand of DNA that is not used as a template for the synthesis of RNA. Its sequence matches the transcribed RNA.

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Direction of Transcription

The direction in which RNA polymerase synthesizes RNA.

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RNA

A nucleic acid present in all living cells that plays a crucial role in protein synthesis.

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Ribose vs Deoxyribose

Difference between DNA and RNA: DNA has deoxyribose sugar, RNA has ribose sugar.

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DNA vs RNA: Strands

DNA is usually double-stranded, while RNA is usually single-stranded.

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Uracil vs Thymine

RNA uses uracil (U) instead of thymine (T) as a base.

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RNA's Role

RNA uses the information stored in DNA to create proteins.

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Study Notes

RNA Polymerases: Eukaryotes vs. Prokaryotes

  • Prokaryotes: only one RNA polymerase
  • Eukaryotes: three RNA polymerases
    • RNA polymerase I transcribes rRNA genes
    • RNA polymerase II transcribes protein-encoding genes
    • RNA polymerase III transcribes tRNA genes and 5S rRNA genes

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Description

This quiz explores the functions and characteristics of RNA polymerases in eukaryotes and their role in transcription. Additionally, it delves into the process of alternative splicing and its significance in gene expression and organism development. Test your knowledge on these fundamental concepts in molecular biology.

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