Protein Synthesis Initiation in Prokaryotes and Eukaryotes

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Which of the following is NOT a requirement for RNA polymerase during transcription?

A DNA template

A divalent metal ion (Mg2+ or Mn2+)

Deoxyribonucleoside triphosphates (correct)

Ribonucleoside triphosphates

What is the role of RNA polymerase in the process of transcription?

Initiating and elongating RNA chains (correct)

Assisting in protein synthesis at the ribosome

Providing a primer for RNA synthesis

Reading mRNA start and stop signals

In which direction does the synthesis occur during RNA and DNA synthesis?

Bidirectional

3′-to-5′ direction

Random direction

5′-to-3′ direction (correct)

What drives the synthesis of RNA during transcription?

Pyrophosphate hydrolysis Signup and view all the answers

Which nucleophilic attack occurs during the elongation of RNA chains?

3′–OH attacks the 5′ carbon of ribose sugar Signup and view all the answers

What type of information do RNA polymerases take from DNA templates?

Base composition Signup and view all the answers

What is the significance of the 'cap' structure added to the 5′ end of eukaryotic mRNA?

Facilitates translation initiation Signup and view all the answers

Why are tRNAs called adaptor molecules in protein synthesis?

They bring amino acids to the mRNA Signup and view all the answers

Which part of the tRNA molecule attaches to the amino acid?

CCA terminus Signup and view all the answers

How many nucleotides encode a single amino acid according to the genetic code?

Three nucleotides Signup and view all the answers

What term describes the phenomenon where most amino acids are encoded by more than one codon?

Redundancy Signup and view all the answers

What is the role of the poly(A) tail added to the 3′ end of eukaryotic mRNA?

Stabilizes the mRNA Signup and view all the answers

What type of amino acid is carried by the initiator tRNA in prokaryotes during protein synthesis?

Formylmethionine Signup and view all the answers

Which sequence precedes the initiating AUG codon in prokaryotes and base pairs with ribosomal RNA?

Shine–Dalgarno sequence Signup and view all the answers

What establishes the reading frame in protein synthesis by determining the order of three nonoverlapping nucleotides?

Location of the initiator codon Signup and view all the answers

Why is the genetic code nearly universal among most organisms?

To minimize deleterious effects of mutations Signup and view all the answers

In which organisms might we observe variations in the genetic code, such as codons typically representing stop codons encoding amino acids?

Mitochondria Signup and view all the answers

What are the distinguishing features of eukaryotic genes that contribute to their mosaicism?

Introns and exons alternate along the gene sequence Signup and view all the answers