Protein Biosynthesis Overview
34 Questions
0 Views

Protein Biosynthesis Overview

Created by
@GaloreRhodium8872

Podcast Beta

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary function of mRNA in the cell?

  • It carries a portion of the DNA code to other parts of the cell. (correct)
  • It acts as a messenger between organelles.
  • It synthesizes proteins directly.
  • It serves as a storage molecule for genetic information.

    • During which cellular process is mRNA synthesized?

  • Replication
  • Transcription (correct)
  • Translocation
  • Translation

    • Why is mRNA larger than the protein it codes for?

  • As a result of the multi-step processing required for mRNA.
  • Due to the presence of non-coding regions called introns. (correct)
  • Because proteins are formed from smaller units than nucleotides.
  • Because mRNA has a higher nucleotide weight than amino acids.

    • What does the wobble hypothesis refer to in genetics?

    <p>The optional nature of the third base in a codon.</p> Signup and view all the answers

    What is the main target of most antibiotics in prokaryotic cells?

    <p>Elongation cycle of ribosomes</p> Signup and view all the answers

    What role does the termination factor play during protein biosynthesis?

    <p>It signals the ribosome to stop translation at a stop codon.</p> Signup and view all the answers

    Which of the following is NOT an actor involved in the initiation phase of protein biosynthesis?

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

    In the elongation phase of protein synthesis, which component is responsible for specifying the aminoacyl-tRNA?

    <p>mRNA codon</p> Signup and view all the answers

    What component is essential for the hydrolysis of the polypeptide chain during termination?

    <p>Termination factor</p> Signup and view all the answers

    Which of the following factors is involved in moving tRNA during the elongation phase?

    <p>EF-G</p> Signup and view all the answers

    What is the role of the small subunit of the ribosome?

    <p>Binds initiation factors and initiator tRNA</p> Signup and view all the answers

    Which rRNA subunits are found in the large subunit of the ribosome?

    <p>23S and 5S</p> Signup and view all the answers

    What sequence establishes contact between ribosomes and mRNA?

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

    What function does the large subunit primarily serve during protein synthesis?

    <p>Peptide bond formation</p> Signup and view all the answers

    What type of RNA composes the ribosome?

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

    How many nucleic acid types are present in the ribosomal complex described?

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

    Which of the following is NOT a function of the ribosome?

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

    Which component of the ribosome is responsible for binding the aminoacyl-tRNA?

    <p>Large subunit</p> Signup and view all the answers

    What is the primary role of ribosomes in protein biosynthesis?

    <p>Catalyzing peptide bond formation</p> Signup and view all the answers

    How many ribosomes are typically found in a single cell?

    <p>Around 15,000</p> Signup and view all the answers

    Which of the following enzymes play a role in the ribosome's functioning?

    <p>20 enzymes and various auxiliary enzymes</p> Signup and view all the answers

    What percentage of cellular energy is consumed during protein synthesis?

    <p>90%</p> Signup and view all the answers

    What prefix is used for ribosomal proteins found in the small subunit?

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

    Which ribosomal protein function is associated with stabilizing rRNA?

    <p>Various ribosomal proteins have this role</p> Signup and view all the answers

    What constitutes a polysome?

    <p>Ribosomes attached to the same mRNA strand</p> Signup and view all the answers

    Which of the following statements about ribosomal proteins is incorrect?

    <p>All proteins are adjacent to the amino acid transferase center</p> Signup and view all the answers

    What is the role of the localization sequence on the N-terminus of proteins?

    <p>It acts as a zip code for directing protein locations.</p> Signup and view all the answers

    Which structure serves as the endpoint for protein sorting after they leave the endoplasmic reticulum?

    <p>Golgi apparatus</p> Signup and view all the answers

    What is the primary function of ribosomes bound to the endoplasmic reticulum?

    <p>Synthesis of secretory and membrane proteins</p> Signup and view all the answers

    What is the process involving the signal recognition particle?

    <p>It aids in the transport of ribosomes to the ER.</p> Signup and view all the answers

    How many forms of the Golgi apparatus are there?

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

    What happens to proteins once they enter the endoplasmic reticulum?

    <p>They are processed for transport to various destinations.</p> Signup and view all the answers

    Which component is NOT involved in moving proteins from the ER to the Golgi apparatus?

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

    Why is it significant that 'what happens in the ER doesn’t stay in the ER'?

    <p>Proteins synthesized in the ER are sent to other organelles for further processing.</p> Signup and view all the answers

    Study Notes

    Protein Biosynthesis

    • The process of protein synthesis is divided into four stages: Initiation, Elongation, Termination, and Recycling.
    • Initiation: This stage involves the assembly of the ribosome, mRNA, and the initiator tRNA.
      • The mRNA binds to the 30S ribosomal subunit, and the initiator tRNA binds to the start codon (AUG).
      • The 50S ribosomal subunit then joins the complex, forming the 70S ribosome.
    • Elongation: This stage involves the addition of amino acids to the growing polypeptide chain.
      • The mRNA is translated from 5' to 3', and the tRNA brings the corresponding amino acid to the ribosome, where it binds to the A site.
      • The amino acid is then transferred to the polypeptide chain in the P site.
      • The ribosome then moves to the next codon on the mRNA, and the empty tRNA exits the ribosome through the E site.
    • Termination: This stage occurs when the ribosome reaches a stop codon on the mRNA.
      • A termination factor binds to the stop codon, causing the release of the polypeptide chain from the ribosome.
    • Recycling: The ribosome subunits, mRNA, and tRNA molecules dissociate from each other.

    Ribosomal Proteins

    • Proteins found in the small subunit are prefixed S; those in the large subunit are prefixed L.
    • Ribosomal proteins have various roles:
      • Stabilizing rRNA
      • Accelerating peptide bond formation (L27 and L16)
      • Participating in extra-ribosomal functions
    • No proteins are proximate to the amino acid transferase center of the ribosome.

    Ribosomes

    • Ribosomes are made up of proteins and rRNA.
    • The small subunit contains the 16S rRNA subunit (1542 nt).
    • The large subunit contains the 23S (2900 nt) and 5S (120 nt) rRNAs.
    • All the rRNAs have well-defined secondary structures.

    Polysomes

    • Polysomes are groups of ribosomes attached to the same mRNA.
    • They enable synchronous translation, meaning multiple ribosomes can translate a single mRNA molecule simultaneously, increasing the efficiency of protein synthesis.

    Messenger RNA

    • mRNA carries genetic information from DNA to the ribosomes for protein synthesis.
    • It is synthesized during transcription, where a single strand of DNA is decoded by RNA polymerase.
    • It is a single-stranded molecule composed of nucleotides.

    Wobble Hypothesis

    • The wobble hypothesis explains how a single tRNA molecule can recognize multiple codons encoding the same amino acid.
    • The third base in a codon is considered "optional" and can exhibit some flexibility in its pairing with the anticodon.
    • This flexibility allows for a smaller number of tRNAs to decode all the codons in the genetic code.

    Antibiotic Translation Inhibitors

    • Many antibiotics target prokaryotic ribosomes, particularly the elongation cycle.
    • These antibiotics inhibit protein synthesis by binding to the ribosome and interfering with its function.

    Secretory and Membrane Proteins

    • These proteins are made on ribosomes bound to the endoplasmic reticulum (ER).
    • They contain a signal sequence on their N-terminus that directs them to the ER.

    ER-Golgi-Membrane

    • The Golgi apparatus plays a crucial role in modifying and packaging proteins.
    • It consists of three compartments:
      • cis Golgi (near to ER)
      • middle Golgi
      • trans Golgi (far from ER)
    • The Golgi facilitates protein transport to the membrane either in the form of cisternae or vesicles.

    Signal Recognition Particle

    • The signal recognition particle (SRP) is a molecular chaperone that escorts ribosomes carrying nascent secretory proteins to the ER.
    • It binds to the signal sequence on the protein and then interacts with a receptor on the ER membrane, guiding the ribosome to the ER.

    Shine-Dalgarno Sequence

    • This sequence is a pyrimidine-rich sequence on the ribosome that establishes contact with a purine-rich sequence on the mRNA.
    • It helps to align the mRNA with the ribosome, allowing for efficient initiation of translation.

    Studying That Suits You

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

    Quiz Team

    Related Documents

    Medicinal Biochemistry I Translation & Trafficking PDF 2024

    Description

    Explore the intricate process of protein biosynthesis, which includes the stages of Initiation, Elongation, Termination, and Recycling. This quiz will test your understanding of how ribosomes, mRNA, and tRNA work together to create proteins. Dive deep into each stage and challenge your knowledge of molecular biology.

    More Like This

    Ribosome Structure and Function
    7 questions

    Ribosome Structure and Function

    EnjoyablePhosphorus7116 avatar
    EnjoyablePhosphorus7116
    Ribosomes: Function and Location
    3 questions

    Ribosomes: Function and Location

    StatuesquePrimrose avatar
    StatuesquePrimrose
    Structure and Function of rRNA in Protein Synthesis
    9 questions

    Structure and Function of rRNA in Protein Synthesis

    RicherHarmony3335 avatar
    RicherHarmony3335
    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser