transcription

• What is the first step of gene expression?

  Transcription

  
• What is the main purpose of transcription?

  To copy the DNA sequence of a gene into RNA

  
• What types of RNA are synthesized during transcription?

  mRNA, tRNA, rRNA, and ncRNA
• What is the role of messenger RNA (mRNA)?

  It encodes the amino acid sequences of polypeptides
• What is the function of transfer RNA (tRNA)?

  It reads the mRNA and transfers the appropriate amino acid to a growing polypeptide chain
• What is the role of ribosomal RNA (rRNA)?

  It is a constituent of ribosomes that synthesize proteins
• What are noncoding RNAs (ncRNAs) involved in?

  They have a variety of catalytic, structural, and regulatory functions
• What is the transcriptome?

  The sum of all the RNA molecules produced in a cell under a given set of conditions

  
• How does transcription differ from DNA replication?

  Transcription is more selective and depends on the transcriptome
• What enzyme synthesizes RNA during transcription?

  RNA polymerase

  
• In which direction does RNA polymerase build a new RNA strand?

  In the 5’ to 3’ direction

  
• What happens if there is a G in the DNA template during transcription?

  RNA polymerase will add a C to the new RNA strand

  
• What is a key characteristic of RNA polymerases regarding proofreading?

  They lack a 3’→5’ exonuclease activity
• How many types of RNA polymerase do humans and other eukaryotes have?

  Three types: I, II, and III
• What additional types of RNA polymerase do plants have?

  Two types: IV and V
• What is required for RNA synthesis?

  A DNA template

  
• What is the template strand in transcription?


  The strand that serves as a template for RNA synthesis

  
• What is the coding strand in transcription?

  The complementary strand that is identical in base sequence to the RNA

  
• What is a transcription bubble?

  The area containing RNA polymerase, DNA, and the newly forming RNA

  
• What is a promoter in transcription?

  A DNA sequence required for RNA polymerase to bind and initiate transcription

  
• What is the consensus sequence in a promoter?

  A part of the promoter recognized by RNA polymerase
• What are the stages of transcription?

  Initiation, elongation, and termination
• What occurs during the initiation stage of transcription?

  Binding and formation of close and open complexes

  
• What happens during the termination stage of transcription?

  RNA polymerase encounters a stop signal, leading to the end of transcription

  
• What are the two ways transcription can terminate?

  Rho-dependent and Rho-independent termination

  
• How does eukaryotic transcription differ from bacterial transcription?

  Eukaryotic transcription is more complex and involves multiple RNA polymerases and transcription factors

  
• Where does transcription occur in eukaryotic cells?

  In the nucleus
• What is the TATA box?

  A DNA sequence that indicates where a genetic sequence can be read and decoded

  
• What are transcription factors?

  Proteins necessary for the initiation of transcription that are not part of RNA polymerase
• What is the role of enhancers in transcription?

  They activate the transcription of targeted genes by transforming signals from transcription factors
• What is produced during eukaryotic transcription?

  A pre-mRNA molecule called a primary transcript

  
• What modifications occur during mRNA maturation in eukaryotes?

  5' cap addition, 3' poly(A) tail addition, and splicing out introns

  
• What is the function of the 5' cap in mRNA maturation?

  It protects the transcript from degradation and helps the ribosome attach to the mRNA

  
• When does the addition of the 5' cap occur during transcription?

  After the first 20 to 30 nucleotides of the transcript have been added
• What is the purpose of the 3' poly(A) tail addition?

  To protect mRNA from enzymatic destruction

  
• What are exons and introns?

  Exons are coding segments, while introns are noncoding regions that interrupt the coding sequence
• What happens during splicing in mRNA maturation?

  Introns are removed, and exons are joined together to form mature mRNA

  
• What is alternative splicing?

  A process where exons from the same gene are joined in different combinations to produce different mRNA transcripts

  
• How can a single gene give rise to multiple products?

  Through differential mRNA processing, including alternative splicing

  
• What are the key components and processes involved in transcription?

  • Transcription is the first step of gene expression.
  • RNA polymerase synthesizes RNA from a DNA template.
  • The transcriptome is the sum of all RNA molecules produced in a cell.
  • Promoters are DNA sequences that initiate transcription.
  • Transcription stages: initiation, elongation, termination.
  • Eukaryotic transcription involves additional complexity, including transcription factors and mRNA maturation.