Bacterial Transcription and Translation Mechanisms
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Questions and Answers

What role does the MerR protein play in bacterial transcriptional regulation?

  • It acts as a transcriptional repressor only.
  • It phosphorylates response regulator proteins.
  • It binds to RNA polymerase to enhance binding.
  • It changes the spacing and orientation of promoter elements. (correct)

    • Attenuation is a mechanism that is only present in eukaryotic cells.

    False

    What is the function of the sensor kinase in two-component signal transduction pathways?

    To detect specific molecules in the environment and become autophosphorylated.

    In the absence of sufficient tryptophan, bacterial ribosomes may encounter a lack of ______.

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

    Match the following key components of bacterial transcription with their functions:

    <p>MerR = Bends DNA to adjust promoter spacing Sensor Kinase = Detects external molecules Response Regulator = Acts as transcriptional activator or repressor Attenuation = Regulates transcription by competition with ribosomes</p> Signup and view all the answers

    Which amino acid is recognized by the UAG stop codon and has its own aminoacyl-tRNA synthetase?

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

    Regulatory RNAs are only found in eukaryotic organisms.

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

    What is the start codon in mRNA translation?

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

    Programmed frameshifting most often occurs by moving ___ nucleotide(s) from the original reading frame.

    <p>+1 or -1</p> Signup and view all the answers

    What is the function of aminoacyl-tRNA synthetases?

    <p>To attach amino acids to tRNA</p> Signup and view all the answers

    Match the following components related to tRNA and codons:

    <p>UGA = Stop codon UAU = Start codon Sec = Selenocysteine tRNA Pyl = Pyrrolysine tRNA</p> Signup and view all the answers

    What critical RNA element interacts with the RNA binding domain of the EFTu-like protein?

    <p>3' UTR element</p> Signup and view all the answers

    The correct amino acids are chosen in a three-step process by aminoacyl-tRNA synthetases.

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

    The primary transcripts of regulatory RNA molecules are usually not processed.

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

    What is indicated by the three-letter superscript in tRNA molecules?

    <p>The specific cognate amino acid loaded onto the tRNA.</p> Signup and view all the answers

    The ribosome has three binding sites for tRNAs: A, P, and ___ .

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

    What happens during programmed frameshifting?

    <p>The reading frame is shifted, causing different codons to be read and leading to a different peptide being produced.</p> Signup and view all the answers

    What is the primary role of snoRNAs in a cell?

    <p>To guide RNA modification</p> Signup and view all the answers

    Match the ribosomal RNA components with their functions:

    <p>16S rRNA = Mediates interaction between tRNA and mRNA 23S rRNA = Found in the peptidyl transferase center rRNA = Composes ribosomes along with ribosomal proteins Initiator tRNA = Begins the translation process at the start codon</p> Signup and view all the answers

    Which site of the ribosome is responsible for the formation of peptide bonds?

    <p>P site</p> Signup and view all the answers

    Eukaryotic mRNAs contain a poly(A) tail at their 5' end.

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

    The editing site of aminoacyl-tRNA synthetases prevents only larger amino acids from attaching to tRNA.

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

    What is the purpose of adding a 7-methylguanine cap to eukaryotic mRNAs?

    <p>To protect mRNAs from degradation and aid in translation.</p> Signup and view all the answers

    The 5’ cap is added during __________.

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

    What is the process called that involves the ribosome moving along the mRNA and forming peptide bonds?

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

    Match the RNA modifications to their functions:

    <p>5’ cap = Protects from degradation 3’ poly(A) tail = Enhances translation snoRNAs = Directs RNA modification Alternative polyadenylation = Regulates mRNA stability</p> Signup and view all the answers

    What is the function of the C-terminal domain (CTD) of RNA Pol II?

    <p>Mediates mRNA processing</p> Signup and view all the answers

    What is the primary function of riboswitches in gene regulation?

    <p>To bind small molecules and regulate synthesis</p> Signup and view all the answers

    Small nucleolar RNAs (snoRNAs) are typically longer than 300 nucleotides.

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

    Riboswitches can only prevent transcription.

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

    Who were awarded the Nobel Prize in 2006 for their discovery related to RNA interference?

    <p>Andrew Fire and Craig Mello</p> Signup and view all the answers

    What enzyme is responsible for adding the poly(A) tail to eukaryotic mRNAs?

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

    Riboswitches can block the __________ sequence to stop translation.

    <p>Shine-Dalgarno</p> Signup and view all the answers

    Match the types of small RNAs with their characteristics:

    <p>siRNAs = Derived from long double-stranded RNAs miRNAs = Regulate gene expression by mRNA degradation piRNAs = Interact with Piwi proteins to suppress transposons snoRNAs = Involved in processing ribosomal RNA</p> Signup and view all the answers

    What happens when thiamine levels are low concerning riboswitches?

    <p>The 5’ UTR structure no longer blocks Shine-Dalgarno sequence</p> Signup and view all the answers

    Small RNAs in eukaryotes are typically longer than 50 nucleotides.

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

    What are the main classes of eukaryotic small regulatory RNAs?

    <p>siRNAs, miRNAs, piRNAs</p> Signup and view all the answers

    What is the main benefit of RNA processing?

    <p>Contributes to regulation of gene activity</p> Signup and view all the answers

    All RNA processing occurs exclusively through protein involvement.

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

    What role does RNase P play in tRNA processing?

    <p>RNase P cleaves the 5' end of tRNAs during their processing.</p> Signup and view all the answers

    The addition of _ to the 3’ ends of tRNAs serves as the attachment site for amino acids.

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

    Match the enzymes to their RNA processing activities:

    <p>RNase III = Cleaves bacterial rRNAs RNase P = Cleaves tRNAs Exonucleases = Remove nucleotides from the ends of RNA Endonucleases = Cleaves RNA within the strand</p> Signup and view all the answers

    How many different RNA modifications have been observed in tRNAs?

    <p>80</p> Signup and view all the answers

    Exonucleases are generally specific to the sequence of nucleotides.

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

    What are the two common modifications found in rRNA?

    <p>Ribose 2’-O-methylation and pseudouridylation.</p> Signup and view all the answers

    During alternative splicing, different combinations of _ are removed from precursor RNA.

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

    What type of RNA processing complex contains both RNA and protein?

    <p>Ribonucleoproteins (RNPs)</p> Signup and view all the answers

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