DNA transcription

• What is the process of gene expression that involves the synthesis of RNA from DNA?

  Transcription

  
• What is the role of mRNA in gene expression?

  Messenger RNA carries the genetic information from DNA to the ribosome

  
• What does tRNA stand for?

  Transfer RNA
• What does rRNA stand for?

  Ribosomal RNA
• What is the structure of RNA?

  RNA is a long unbranched chain of ribonucleotides joined by 3’ to 5’ phosphodiester bonds

  
• What are the four bases found in RNA?


  Adenine (A), Guanine (G), Cytosine (C), Uracil (U)

  
• What sugar is found in RNA?

  Ribose
• What is the typical conformation of RNA?

  RNA is usually single-stranded
• What enzyme catalyzes transcription?

  RNA Polymerase (RNAP)
• What does RNAP use to transcribe RNA?

  RNAP uses ribonucleotide triphosphates (NTPs)
• In which direction does RNAP read the DNA template during transcription?

  RNAP reads the template 3’ to 5’ and synthesizes RNA 5’ to 3’
• Is a primer required for transcription?

  No primer is required for transcription
• What part of DNA codes for proteins?

  Only genes code for proteins
• What are the distinct signals within DNA that indicate the start and end of transcription?

  Distinct ‘start’ and ‘stop’ signals within the DNA sequence
• Where does transcription begin and end?

  Transcription begins at the ‘Promoter’ and ends at the ‘Terminator’
• What is the TATAAT box?

  The TATAAT box is a conserved sequence found at -10 in the promoter region
• What is the role of the 5' UTR in mRNA?

  The 5' UTR contains information to instruct translation

  
• What is the function of the 3' UTR in mRNA?

  The 3' UTR contains the polyadenylation sequence

  
• What is the significance of the polyadenylation signal sequence?

  The polyadenylation signal recruits endonuclease to cleave mRNA
• What happens after the endonuclease cleaves mRNA?

  Poly(A) Polymerase adds ~40-250 A residues to the cleaved 3' end
• What is the role of the 5' cap in mRNA processing?

  The 5' cap protects the mRNA from nuclease attack and guides it through the nuclear pore

  
• What is splicing in mRNA processing?

  Splicing removes non-coding intron sequences from the mRNA

  
• What is the spliceosome?

  The spliceosome is a molecular machine that carries out splicing
• What is alternative splicing?

  Alternative splicing produces different mature mRNAs from a single primary transcript

  
• How many genes do humans have compared to the number of proteins they produce?

  Humans have 30,000 - 40,000 genes but produce up to 100,000 proteins
• What is the role of ribosomes in translation?

  Ribosomes translate the information in mRNA into amino acids

  
• What is the open reading frame (ORF)?

  The ORF is a set of codons that run continuously, bounded by initiation and termination codons
• What is the significance of the start codon AUG?

  AUG is the typical first codon in protein synthesis
• What are the types of genetic mutations?

  Silent, missense, and nonsense mutations
• What does it mean for the genetic code to be specific?

  Each codon always codes for the same amino acid

  
• What does it mean for the genetic code to be universal?

  The genetic code applies to all species and is conserved from early evolution
• What does redundancy in the genetic code refer to?

  A given amino acid can be coded for by several different codons

  
• What does it mean for the genetic code to be non-overlapping?

  The code is read from a fixed starting point as a continuous sequence of bases, taken 3 at a time
• What is the structure of tRNA?

  tRNA has an extensive secondary structure leading to a characteristic “cloverleaf” shape
• What is the role of aminoacyl-tRNA-synthetases?

  Aminoacyl-tRNA-synthetases couple amino acids to the correct tRNA molecule
• What is the function of the anticodon arm in tRNA?

  The anticodon arm base pairs with the mRNA sequence

  
• What is the wobble base in tRNA?

  The wobble base is the last (3’) base in the codon that binds with the first (5’) base in the anticodon

  
• What occurs during the initiation phase of translation?

  Initiation involves the assembly of ribosomal subunits, mRNA, tRNA, GTP, and initiation factors

  
• What is the role of the ribosome's A, P, and E sites?

  A site accepts the next tRNA, P site contains the amino acid chain, and E site harbors deacylated tRNA

  
• What happens during the elongation phase of translation?

  Elongation involves the addition of amino acids to the growing chain and ribosome movement along mRNA