RNA Structure and Transcription

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Questions and Answers

Which process occurs in the nucleus of eukaryotic cells?

  • RNA transcription (correct)
  • Translation
  • Post-transcription processing
  • DNA replication

Which type of RNA transports amino acids to the ribosome?

  • Messenger RNA (mRNA)
  • Ribosomal RNA (rRNA)
  • Transfer RNA (tRNA) (correct)
  • All of the above

What is the central dogma of molecular biology?

  • RNA → Protein → DNA
  • Protein → RNA → DNA
  • Protein → DNA → RNA
  • DNA → RNA → Protein (correct)

Which enzyme catalyzes the linkage of ribonucleotides during transcription?

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

What is the error rate of RNA polymerase during transcription?

<p>1 in 104 nucleotides (A)</p> Signup and view all the answers

Which of the following is a function of non-coding RNA (ncRNA)?

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

Which of the following is true about transcription in bacteria?

<p>Sigma factor binds the core enzyme (A)</p> Signup and view all the answers

Which of the following is true about catalytic RNA (ribozymes)?

<p>Catalytic RNA can catalyze its own splicing (D)</p> Signup and view all the answers

Which of the following can cause disease when mutated at splice sites?

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

What is the first modification that happens to bacterial RNA during RNA processing?

<p>Addition of a 5' cap (D)</p> Signup and view all the answers

Which enzyme is responsible for unwinding a 12-15 bp segment of the DNA during transcription initiation?

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

What is the function of the activator in transcription initiation?

<p>Attract RNA pol II to the start point (B)</p> Signup and view all the answers

Which proteins are required for transcription elongation in eukaryotes?

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

What is the purpose of RNA splicing?

<p>To remove noncoding sequences (introns) (D)</p> Signup and view all the answers

Which enzyme is responsible for unwinding a 12-15 bp segment of the DNA during transcription initiation?

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

What is the function of the activator in transcription initiation?

<p>To recruit RNA polymerase (C)</p> Signup and view all the answers

Which proteins are required for transcription elongation in eukaryotes?

<p>Elongation factors and chromatin remodeling complexes (C)</p> Signup and view all the answers

Which of the following is the first modification that happens to bacterial RNA during RNA processing?

<p>Addition of 5'-methylguanosine cap (D)</p> Signup and view all the answers

What is the purpose of RNA splicing?

<p>To join exons together (C)</p> Signup and view all the answers

Which enzyme catalyzes the linkage of ribonucleotides during transcription?

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

Which process occurs in the nucleus of eukaryotic cells?

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

Which of the following is true about RNA transcription in prokaryotes?

<p>Transcription and translation occur simultaneously (D)</p> Signup and view all the answers

Which of the following is true about RNA transcription in eukaryotes?

<p>Transcription occurs in the nucleus (A)</p> Signup and view all the answers

Which type of RNA associates with proteins to form ribosomes in the cytoplasm?

<p>Ribosomal RNA (rRNA) (B)</p> Signup and view all the answers

Which type of RNA transports amino acids to the ribosome?

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

Which of the following is true about RNA and DNA?

<p>RNA is single stranded, while DNA is double stranded (A)</p> Signup and view all the answers

What is the flow of genetic information according to the central dogma of molecular biology?

<p>DNA → RNA → Protein (B)</p> Signup and view all the answers

Which type of RNA is formed complementary to one strand of DNA and codes for proteins?

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

Which of the following is true about transcription in bacteria?

<p>Transcription in bacteria involves three RNA polymerases (A)</p> Signup and view all the answers

What is the function of the sigma (σ) factor in bacterial transcription?

<p>It recognizes and binds to the promoter region (C)</p> Signup and view all the answers

Which of the following is true about general/basal transcription factors?

<p>They are proteins needed at nearly all promoters used by RNA polymerase II (A)</p> Signup and view all the answers

What is the consensus sequence that is typically located ~25bp upstream of the initiation site in eukaryotic RNA polymerase II promoters?

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

Which of the following is true about RNA polymerase error rates during transcription?

<p>RNA polymerase has a higher error rate than DNA polymerase (A)</p> Signup and view all the answers

Which of the following is a function of transcription factors in eukaryotic transcription?

<p>To recognize and bind to the promoter region (D)</p> Signup and view all the answers

Which of the following is true about the scrunching mechanism in bacterial transcription?

<p>It opens the dsDNA to form a transcription bubble (B)</p> Signup and view all the answers

Which of the following is true about alternative splicing?

<p>It can produce different forms of a protein from the same gene (A)</p> Signup and view all the answers

Which of the following can cause disease when mutated at splice sites?

<p>Thalassemia and Breast cancer (BRCA 1) (D)</p> Signup and view all the answers

Which of the following is true about mRNA?

<p>It is the major component of the total RNA (A)</p> Signup and view all the answers

Which of the following is true about DNA and RNA?

<p>They contain sugar, phosphate, and bases (B)</p> Signup and view all the answers

What is the product of transcription called?

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

Which of the following is required for transcription initiation?

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

Which of the following is true about bacterial RNA processing?

<p>The first modification is the addition of a 5' cap (C)</p> Signup and view all the answers

Which of the following is true about DNA gyrase in bacteria?

<p>It constantly keeps positive supercoils in DNA (D)</p> Signup and view all the answers

What is the first modification that happens to bacterial RNA during RNA processing?

<p>Addition of a 5' cap (D)</p> Signup and view all the answers

Flashcards

Transcription

The process of creating an RNA molecule using a DNA template.

mRNA

Messenger RNA. It carries the genetic code from DNA to the ribosome for translation into protein.

tRNA

Transfer RNA. It transports amino acids to the ribosome during translation.

Central Dogma

The flow of genetic information from DNA to RNA to protein.

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RNA Polymerase

The enzyme that catalyzes the synthesis of RNA using a DNA template.

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Helicase

An enzyme that unwinds the DNA double helix during transcription initiation.

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Non-coding RNA (ncRNA)

RNA molecules that do not code for proteins. They have diverse functions like regulating gene expression or processing RNA.

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Ribozyme

A catalytic RNA molecule that can act as an enzyme and catalyze specific biochemical reactions.

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Sigma Factor (σ)

A protein in bacteria that helps RNA polymerase recognize and bind to the promoter region of DNA.

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5' Cap

A modified guanine nucleotide added to the 5' end of eukaryotic mRNA transcripts.

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RNA Splicing

The process of removing introns from pre-mRNA and joining exons to form a mature mRNA molecule.

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Alternative Splicing

A process where different combinations of exons can be spliced together from a single pre-mRNA molecule, leading to multiple protein variants.

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TATA Box

A consensus sequence found in eukaryotic promoters approximately 25 base pairs upstream of the transcription start site.

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Activator

A protein that enhances the binding of RNA polymerase to a promoter, increasing transcription.

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Elongation Factor

A protein that helps RNA polymerase move along the DNA template during transcription elongation.

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General Transcription Factors

Proteins in eukaryotes that bind to the promoter region and help RNA polymerase II initiate transcription.

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Transcription Initiation

The process of RNA polymerase binding to the promoter region of DNA and starting RNA synthesis.

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Transcription Elongation

The process of RNA polymerase moving along the DNA template, extending the RNA molecule.

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Transcription Termination

The process of ending transcription, releasing the newly synthesized RNA molecule and detaching RNA polymerase from DNA.

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DNA Gyrase

An enzyme found in bacteria that relieves supercoiling ahead of the replication fork.

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Fidelity

The accuracy of an enzyme in copying DNA or RNA, measured by errors per nucleotide.

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Introns

Non-coding sequences within a gene that are removed during RNA splicing.

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Exons

Coding sequences within a gene that are spliced together to form mature mRNA.

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Splice Site

The specific sequence in pre-mRNA that signals where splicing should occur.

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Promoter

A DNA sequence that signals the start of a gene and where RNA polymerase binds to begin transcription.

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Translation

The process of converting mRNA into a protein.

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Ribosome

The site of protein synthesis, where mRNA and tRNA interact to create a protein.

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Amino Acid

The building blocks of proteins.

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Genetic Code

The set of rules that specifies how sequences of three mRNA nucleotides (codons) correspond to amino acids.

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Study Notes

Nucleus and RNA Processes

  • Transcription occurs in the nucleus of eukaryotic cells.
  • mRNA (messenger RNA) is formed complementary to one strand of DNA and codes for proteins.
  • tRNA (transfer RNA) transports amino acids to the ribosome.

Central Dogma of Molecular Biology

  • The central dogma describes the flow of genetic information as DNA → RNA → Protein.

Enzymatic Functions

  • RNA polymerase catalyzes the linkage of ribonucleotides during transcription.
  • The error rate of RNA polymerase during transcription is relatively low, with approximately 1 error per 10,000 nucleotides.
  • The enzyme helicase unwinds a 12-15 bp segment of DNA during transcription initiation.

RNA Types and Functions

  • Non-coding RNA (ncRNA) has functions such as regulating gene expression, RNA processing, and other cellular processes.
  • Ribozymes are catalytic RNAs that can act as enzymes and can catalyze specific biochemical reactions.

Bacterial vs Eukaryotic Transcription

  • Transcription in bacteria occurs in the cytoplasm and does not involve extensive RNA processing.
  • Eukaryotic transcription requires general transcription factors for promoter recognition and RNA polymerase II.
  • The sigma (σ) factor is crucial for initiating transcription in bacteria by binding to the promoter region.

RNA Modification and Processing

  • The first modification of bacterial RNA during processing is the addition of a 5' cap.
  • RNA splicing removes introns and joins exons to create a mature mRNA molecule.
  • Mutations at splice sites can lead to diseases by affecting gene expression.

Transcription Initiation and Elongation

  • Activators enhance transcription initiation by helping RNA polymerase bind to DNA.
  • Eukaryotic transcription elongation requires additional proteins, including elongation factors.

Consensus Sequences

  • The consensus sequence commonly found approximately 25 bp upstream of the initiation site in eukaryotic RNA polymerase II promoters is the TATA box.

Additional RNA Insights

  • mRNA is the product of transcription that carries the genetic code from DNA to the ribosome for translation.
  • Alternative splicing allows a single gene to produce multiple protein variants by rearranging exons.

Genetic Information and Errors

  • The flow of genetic information is directed by the central dogma, ensuring proper protein synthesis from the genetic template.
  • RNA polymerase has a higher fidelity than DNA polymerase, but errors can still occur in RNA synthesis.

Other Notable Points

  • DNA gyrase is essential in bacteria for relieving supercoiling ahead of the replication fork.
  • General/basal transcription factors in eukaryotes facilitate the binding of RNA polymerase to the promoter region.

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CMB 31-32 RNA Structure and Transcription BL 2023.pptx

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