Genetic Code and Translation Quiz
48 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What does degeneracy in the genetic code refer to?

  • Each amino acid is encoded by a unique codon.
  • A single amino acid may be encoded by multiple codons. (correct)
  • Codons are read in overlapping segments.
  • The genetic code varies significantly across different species.

Which of the following correctly describes stop codons?

  • They are the most common type of codon.
  • They initiate protein synthesis.
  • They signal the termination of protein synthesis. (correct)
  • They represent specific amino acids.

What is the role of the AUG codon in translation?

  • It terminates protein synthesis.
  • It represents a stop codon and ends protein synthesis.
  • It encodes the amino acid tryptophan.
  • It serves as the start codon and encodes methionine. (correct)

How many different combinations of codons can be formed with three nucleotides?

<p>64 (C)</p> Signup and view all the answers

What happens during translation when an open reading frame (ORF) is identified?

<p>An ORF typically results in the synthesis of a protein. (C)</p> Signup and view all the answers

What distinguishes the reading frames during translation?

<p>A reading frame is dependent on the starting nucleotide. (A)</p> Signup and view all the answers

Which characteristic of the genetic code indicates it is quasi-universal?

<p>It is utilized by virtually all species for protein synthesis. (B)</p> Signup and view all the answers

Which of the following is NOT a feature of the genetic code?

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

What is the primary function of tRNA in translation?

<p>To transport amino acids to the ribosome (A)</p> Signup and view all the answers

What makes up the prokaryotic ribosome?

<p>50S large subunit and 30S small subunit (C)</p> Signup and view all the answers

Which component is essential for the elongation phase of translation?

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

Which of the following correctly describes the ribosome during protein synthesis?

<p>It contains catalytic rRNAs and polypeptides (A)</p> Signup and view all the answers

What is the significance of the anticodon in tRNA?

<p>It pairs with the codon on mRNA (A)</p> Signup and view all the answers

How many ribosomes are typically found in an E. coli cell?

<p>About 150,000 (D)</p> Signup and view all the answers

What are release factors responsible for during translation?

<p>They help in the disassembly of the ribosome (D)</p> Signup and view all the answers

Which of the following correctly describes the ribosomal RNA components in eukaryotic ribosomes?

<p>Various rRNAs in both subunits (D)</p> Signup and view all the answers

What is the role of the 5’ base of the anticodon in tRNA?

<p>It allows for base pairing with multiple mRNA codons. (A)</p> Signup and view all the answers

What is the function of aminoacyl tRNA synthetases?

<p>To charge tRNA molecules with their corresponding amino acids. (C)</p> Signup and view all the answers

Which factor is NOT involved in the initiation complex of prokaryotic translation?

<p>Initiation factor IF5 (C)</p> Signup and view all the answers

What is the role of the Shine-Dalgarno sequence in prokaryotic translation?

<p>It is a ribosome binding site for initiation of translation. (B)</p> Signup and view all the answers

What is produced when adenosine monophosphate (AMP) is added to an amino acid during tRNA charging?

<p>A charged tRNA. (C)</p> Signup and view all the answers

Which of the following bases might be found in the anticodon of a tRNA?

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

What is the first step in the initiation of prokaryotic translation?

<p>Assembly of initiation factor proteins with the ribosome. (B)</p> Signup and view all the answers

How many initiation factors are involved in the assembly of the prokaryotic ribosome during translation initiation?

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

What occurs simultaneously in prokaryotes allowing for rapid cellular response?

<p>Translation and transcription (A)</p> Signup and view all the answers

Where does transcription occur in eukaryotic cells?

<p>Nucleus (D)</p> Signup and view all the answers

What type of modifications may occur after a protein is synthesized?

<p>Cutting parts of the polypeptide chain (C)</p> Signup and view all the answers

Why are bacterial ribosomes targeted by antibacterial drugs?

<p>They are structurally distinct from animal ribosomes (B)</p> Signup and view all the answers

What crucial step is necessary in eukaryotic cells before translation can occur?

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

What role do post-translational modifications serve for proteins?

<p>To assist in protein localization and signaling (D)</p> Signup and view all the answers

Which ribosome subunits do major classes of protein synthesis inhibitors target?

<p>30S and 50S subunits (C)</p> Signup and view all the answers

What is a consequence of the separation of transcription and translation in eukaryotes?

<p>Increased protein stability due to RNA processing (C)</p> Signup and view all the answers

What is the role of the ribosome binding site (RBS) in prokaryotes?

<p>It basepairs with 16S rRNA to facilitate translation initiation. (D)</p> Signup and view all the answers

What is unique about the initiator tRNA that interacts with the AUG codon in prokaryotes?

<p>It carries formylated methionine (fMet). (A)</p> Signup and view all the answers

In eukaryotes, what does the initiation complex recognize to begin translation?

<p>The 5' cap of the mRNA. (A)</p> Signup and view all the answers

What is the primary function of the E (exit) site in the ribosome?

<p>To release tRNAs after their amino acids are incorporated. (A)</p> Signup and view all the answers

Why are methionine (Met) residues not always the first amino acids in mature proteins?

<p>Methionine is removed after translation in many proteins. (C)</p> Signup and view all the answers

What happens to the ribosome after it recognizes the start codon in eukaryotic translation?

<p>The 60S subunit binds to the initiator complex with Met-tRNAi. (D)</p> Signup and view all the answers

How does the eukaryotic ribosome locate the correct start codon?

<p>By scanning the mRNA in the 5' to 3' direction from the 5' cap. (D)</p> Signup and view all the answers

Which site on the ribosome is primarily responsible for peptide bond formation?

<p>P (peptidyl) site. (A)</p> Signup and view all the answers

What triggers the termination of protein synthesis during translation?

<p>The release factors recognize stop codons (D)</p> Signup and view all the answers

Which codons are considered stop codons in the context of translation termination?

<p>UAA, UAG, UGA (B)</p> Signup and view all the answers

What is formed when multiple ribosomes translate a single mRNA simultaneously?

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

In prokaryotes, what allows transcription and translation to occur simultaneously?

<p>Absence of organellar compartmentalization (C)</p> Signup and view all the answers

What happens to the ribosomal subunits after the newly made protein is released?

<p>They dissociate from the mRNA and can be reused (D)</p> Signup and view all the answers

What is the role of release factors (RFs) during translation termination?

<p>To cleave the aminoacyl chain from tRNA (B)</p> Signup and view all the answers

What is the direction of mRNA reading during translation?

<p>5’ to 3’ (C)</p> Signup and view all the answers

During bacterial translation initiation, which component is included in the initiation complex?

<p>Initiator tRNA carrying N-formyl-methionine (A)</p> Signup and view all the answers

Flashcards

Genetic Code

The set of rules that determines how a sequence of nucleotides in DNA or RNA is translated into a sequence of amino acids in a protein.

Codon

A sequence of three nucleotides in DNA or RNA that codes for a specific amino acid.

Start Codon

The codon (usually AUG) that signals the beginning of protein synthesis.

Stop Codon

One of three codons (UAG, UGA, or UAA) that signals the end of protein synthesis.

Signup and view all the flashcards

Degeneracy of the Genetic Code

The ability of multiple codons to code for the same amino acid, providing some buffer against mutations.

Signup and view all the flashcards

Open Reading Frame (ORF)

A continuous stretch of codons in mRNA that starts with a start codon and ends with a stop codon, likely encoding a protein.

Signup and view all the flashcards

Translation

The process of converting the genetic code in mRNA into a chain of amino acids, forming a protein.

Signup and view all the flashcards

Universality of the Genetic Code

The same genetic code is used by almost all living organisms, demonstrating a common ancestor.

Signup and view all the flashcards

Prokaryotic Translation

The process of protein synthesis in prokaryotic cells, where genetic information encoded in mRNA is translated into a polypeptide chain.

Signup and view all the flashcards

Ribosome

A complex cellular organelle composed of ribosomal RNA (rRNA) and proteins, responsible for protein synthesis.

Signup and view all the flashcards

70S Ribosome

The type of ribosome found in prokaryotes, composed of a 50S large subunit and a 30S small subunit.

Signup and view all the flashcards

tRNA

A type of RNA molecule responsible for carrying specific amino acids to the ribosome during protein synthesis.

Signup and view all the flashcards

Anticodon

A three-nucleotide sequence on tRNA that base pairs with a complementary codon on mRNA, ensuring the correct amino acid is added to the polypeptide chain.

Signup and view all the flashcards

Elongation Factors (EFs)

Proteins that assist in the elongation phase of translation, helping to move the ribosome along the mRNA and add amino acids to the polypeptide chain.

Signup and view all the flashcards

Release Factors (RFs)

Proteins that recognize stop codons on mRNA and terminate translation, releasing the completed polypeptide chain from the ribosome.

Signup and view all the flashcards

Wobble Base Pairing

A less strict base pairing rule at the third position of a codon (5' end of anticodon) allowing one tRNA to recognize multiple codons for the same amino acid.

Signup and view all the flashcards

Inosine

A modified base found in some tRNAs that can base pair with multiple bases (A, U, C), further contributing to the 'wobble' effect.

Signup and view all the flashcards

Charged tRNA

A tRNA molecule carrying its specific amino acid, ready for protein synthesis.

Signup and view all the flashcards

Aminoacyl tRNA Synthetase

An enzyme that catalyzes the attachment of the correct amino acid to its corresponding tRNA, ensuring accuracy in protein synthesis.

Signup and view all the flashcards

Prokaryotic Translation Initiation

The assembly of the ribosome complex (small subunit, initiation factors, methionine-carrying tRNA, and mRNA) at the start codon (AUG) to begin protein synthesis.

Signup and view all the flashcards

Ribosome Binding Sequence (RBS)

A specific 8-nucleotide sequence upstream of the start codon on mRNA that helps the ribosome bind and initiate translation in prokaryotes.

Signup and view all the flashcards

Shine-Dalgarno Sequence

Another name for the Ribosome Binding Sequence (RBS) in prokaryotes.

Signup and view all the flashcards

Prokaryotic Translation Initiation Complex

The complete assembly of the ribosome, mRNA, and initiation factors ready to begin protein synthesis in a prokaryote.

Signup and view all the flashcards

RBS (Ribosome Binding Site)

A sequence on mRNA that binds to the small ribosomal subunit, initiating translation in prokaryotes.

Signup and view all the flashcards

Initiator tRNA

The special tRNA that carries formylmethionine (fMet) and binds to the start codon (AUG) in prokaryotes.

Signup and view all the flashcards

Formylmethionine (fMet)

A modified form of methionine, the first amino acid incorporated into a protein in prokaryotes.

Signup and view all the flashcards

5' Cap

A modified guanine nucleotide at the 5' end of eukaryotic mRNA, recognized by the initiation complex.

Signup and view all the flashcards

A-Site (Aminoacyl Site)

The site on the ribosome where incoming charged tRNAs bind, carrying the next amino acid to be added.

Signup and view all the flashcards

P-Site (Peptidyl Site)

The site on the ribosome where the tRNA carrying the growing polypeptide chain resides.

Signup and view all the flashcards

E-Site (Exit Site)

The site on the ribosome where discharged tRNAs leave after releasing their amino acid.

Signup and view all the flashcards

Prokaryotic Transcription and Translation

In prokaryotes, transcription and translation happen simultaneously in the cytoplasm. This allows for a rapid cellular response to changes in the environment.

Signup and view all the flashcards

Eukaryotic Transcription and Translation

In eukaryotes, transcription occurs in the nucleus and translation occurs in the cytoplasm. This separation requires RNA processing for stability before translation.

Signup and view all the flashcards

Post-translational Modifications

After protein synthesis, proteins can be further modified by adding or removing parts. This influences their function, location, and stability within the cell.

Signup and view all the flashcards

Ribosome Differences

Animal cells have 80S ribosomes, while bacteria have 70S ribosomes. This difference makes protein biosynthesis a target for antibacterial drugs.

Signup and view all the flashcards

Antibacterial Drug Targets

Many antibacterial drugs work by inhibiting protein synthesis. They specifically target the 30S or 50S subunits of bacterial ribosomes.

Signup and view all the flashcards

Protein Synthesis Inhibitors

Substances that interfere with the process of protein synthesis in bacteria, often by binding to the ribosome.

Signup and view all the flashcards

30S and 50S Ribosomal Subunits

Bacterial ribosomes are composed of two main subunits: the 30S subunit and the 50S subunit. These subunits play crucial roles in translation.

Signup and view all the flashcards

Translation: From mRNA to Protein

The process of converting the genetic code in mRNA into a chain of amino acids, forming a functional protein.

Signup and view all the flashcards

What happens when a stop codon is reached?

The ribosome encounters a stop codon (UAA, UAG, or UGA), which signals the end of translation. These codons don't have corresponding tRNAs but are recognized by release factors (RFs).

Signup and view all the flashcards

What do release factors do?

Release factors (RFs) are proteins that bind to stop codons in the mRNA. They facilitate the detachment of the newly synthesized polypeptide chain from the tRNA, ending the translation process.

Signup and view all the flashcards

What is a polyribosome?

A polyribosome (or polysome) is a structure consisting of an mRNA molecule with multiple ribosomes attached to it, simultaneously translating the mRNA into proteins.

Signup and view all the flashcards

How do prokaryotes synthesize proteins rapidly?

In prokaryotes, multiple RNA polymerases can simultaneously transcribe the same gene, while many ribosomes concurrently translate the mRNA transcripts, resulting in rapid protein production.

Signup and view all the flashcards

What is the significance of the lack of compartmentalization in prokaryotes?

The absence of organellar compartmentalization in prokaryotes allows transcription and translation to occur simultaneously, streamlining the process of gene expression.

Signup and view all the flashcards

What is the direction of translation on an mRNA?

Translation proceeds along the mRNA from 5' to 3', synthesizing the polypeptide chain from the N-terminus to the C-terminus.

Signup and view all the flashcards

What does the initiation complex consist of?

The initiation complex in bacterial translation comprises the small ribosomal subunit, the mRNA, the initiator tRNA carrying N-formyl-methionine, and initiation factors.

Signup and view all the flashcards

How does the ribosome change after the initiation complex forms?

After the initiation complex forms, the 50S subunit joins the 30S subunit to create an intact ribosome, allowing translation to proceed.

Signup and view all the flashcards

Study Notes

Translation of mRNA into Proteins

  • Translation converts mRNA sequences into polypeptide chains.
  • It's the final step in using genetic information encoded in DNA.

Transcription

  • DNA instructions are transcribed onto mRNA.
  • Ribosomes read mRNA to assemble amino acids into proteins.

RNA Processing

  • Primary RNA transcript undergoes processing.
  • Exons are joined together and introns are removed.
  • Spliced RNA is the final product.

Translation (detailed)

  • mRNA is read in three-nucleotide segments (codons).
  • Each codon corresponds to a specific amino acid.
  • The genetic code defines the correspondence between codons and amino acids.
  • Codons start from the 5' end of the mRNA.
  • Sixty-one codons code for twenty amino acids.
  • Three codons (UAG, UGA, UAA) are stop codons, signaling the end of translation.
  • AUG is a start codon, typically specifying methionine.
  • Translation proceeds in a specific reading frame, typically beginning at AUG.

Features of the Genetic Code

  • Quasi-universal: Similar genetic code is used by most species.
  • Degenerate: Multiple codons code for some amino acids. Reduces harmful impact of mutations.
  • Comma-less and non-overlapping: Codons are read as distinct segments, not overlapping.

Ribosomes

  • Ribosomes are complex macromolecular organelles.
  • Made of RNA and proteins (ribozymes and structural RNAs).
  • Bacterial ribosomes are 70S (50S and 30S subunits).
  • Eukaryotic ribosomes are 80S (60S and 40S subunits).
  • Ribosomes are abundant sites of protein synthesis.
  • They dissociate and reassociate during translation.

Transfer RNAs (tRNAs)

  • Key link between mRNA and protein synthesis.
  • tRNAs are specific for each amino acid. They have an anticodon that pairs with mRNA codons.
  • tRNAs carry the specific amino acid to the ribosome.
  • tRNAs have a three-dimensional structure.
  • One end holds an amino acid; the other anticodon.
  • A single tRNA can base pair with more than one codon.

Initiation of Translation (prokaryotes)

  • Ribosomes assemble around mRNA.
  • Initiator tRNA (carrying methionine) binds to the start codon (AUG).
  • Specific initiation factors involved.

Elongation of the Polypeptide Chain

  • Ribosome moves along mRNA in the 5' to 3' direction
  • tRNA carrying the next amino acid enters the A-site
  • Peptide bonds form between amino acids.
  • Ribosome translocates along the mRNA.
  • tRNA moves to the E-site.
  • The process repeats until a stop codon is reached.

Termination of Translation

  • Stop codons (UAA, UAG, UGA) signal termination.
  • Release factors bind to the stop codon.
  • Polypeptide chain is released.
  • Ribosome subunits dissociate.

Post-translational Modifications

  • Proteins undergo modifications after synthesis.
  • These modifications can include removal of parts, addition of fats, sugars, or small chemical groups.
  • The modifications are often critical for protein function.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

Related Documents

Translation PDF

Description

Test your knowledge on the intricacies of the genetic code and the process of translation. This quiz covers topics such as codons, tRNA functions, ribosome composition, and the nuances of stop codons. Perfect for students studying genetics or molecular biology.

More Like This

Genetic Code and mRNA Translation
10 questions

Genetic Code and mRNA Translation

UndisputedCliché avatar
UndisputedCliché
Genetic Code: Translation in Prokaryotes and Eukaryotes
14 questions

Genetic Code: Translation in Prokaryotes and Eukaryotes

CheerfulPhosphorus5526 avatar
CheerfulPhosphorus5526
Genetic Code and Translation Quiz
14 questions

Genetic Code and Translation Quiz

InvulnerableGold2463 avatar
InvulnerableGold2463
Genetic Code and Translation Quiz
13 questions

Genetic Code and Translation Quiz

TopJasper2023 avatar
TopJasper2023
Use Quizgecko on...
Browser
Open
Browser
Browser