Protein Transport Mechanisms
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Questions and Answers

Which process involves the transport of fully folded proteins through nuclear pores?

  • Transmembrane translocation
  • Gated transport (correct)
  • Endocytosis
  • Vesicular trafficking
  • In which type of transport are proteins unfolded to cross membranes?

  • Transmembrane translocation (correct)
  • Vesicular trafficking
  • Exocytosis
  • Gated transport
  • Which process is known as vesicular trafficking?

  • Transport of proteins in membrane-bound vesicles (correct)
  • Movement of proteins through nuclear pores
  • Direct diffusion of proteins through the cytosol
  • Transport of proteins across membranes in an unfolded state
  • What determines whether a protein remains in the cytosol or follows a particular transport path?

    <p>Presence of sorting signals within the protein</p> Signup and view all the answers

    Which cellular components are targeted by transmembrane translocation?

    <p>Peroxisomes, mitochondria, and chloroplasts</p> Signup and view all the answers

    What is the initial basis for sorting decisions of newly synthesized proteins?

    <p>Targeting sequences</p> Signup and view all the answers

    Which additional modifications can influence the sorting of proteins synthesized on the rough endoplasmic reticulum?

    <p>Addition of sugars and phosphate groups</p> Signup and view all the answers

    Which transport mechanism involves synthesized proteins passing through nuclear pores?

    <p>Gated transport</p> Signup and view all the answers

    Proteins are delivered to the nucleus through a process known as vesicular trafficking.

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

    In transmembrane translocation, polypeptide chains are unfolded to cross membranes.

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

    The transport of proteins to mitochondria involves vesicular trafficking.

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

    The fate of a protein is determined by amino acid sequences known as targeting sequences.

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

    Gated transport involves the movement of unfolded proteins through nuclear pores.

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

    Vesicles are small closed bags made of membrane that carry newly synthesized proteins between compartments.

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

    Proteins synthesized on cytosolic ribosomes do not require unfolding for any type of transport.

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

    Proteins synthesized on the rough endoplasmic reticulum can have additional sorting signals added in the form of sugars and phosphate groups.

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

    Study Notes

    Protein Transport Mechanisms

    • Proteins may fold into their final form as they are synthesized and then move through an aqueous medium to their final destination, remaining folded throughout.
    • Delivery of proteins to the nucleus occurs through gated transport, where proteins are synthesized on cytosolic ribosomes and pass through nuclear pores into the nucleoplasm.

    Transmembrane Translocation

    • Transmembrane translocation involves the transport of unfolded polypeptide chains across one or more membranes to reach their final destination.
    • Proteins destined for the interior of peroxisomes, mitochondria, and chloroplasts are synthesized on cytosolic ribosomes, may fold partially, and are then unfolded for transport across the membrane.

    Vesicular Trafficking

    • Vesicles, small closed bags of membrane, carry newly synthesized proteins from the endoplasmic reticulum to the Golgi apparatus and between other compartments.
    • The fate of a protein, whether to remain in the cytosol or be transported via an alternative path, is determined by sorting signals within the protein itself.

    Targeting Sequences

    • Initial sorting decisions are made based on particular amino acid sequences called targeting sequences.
    • For proteins synthesized on the rough endoplasmic reticulum, additional sorting signals such as sugars and phosphate groups can be added by enzymes that modify the protein's chemical structure.

    Protein Transport Mechanisms

    • Proteins may fold into their final form as they are synthesized and then move through an aqueous medium to their final destination, remaining folded throughout.
    • Delivery of proteins to the nucleus occurs through gated transport, where proteins are synthesized on cytosolic ribosomes and pass through nuclear pores into the nucleoplasm.

    Transmembrane Translocation

    • Transmembrane translocation involves the transport of unfolded polypeptide chains across one or more membranes to reach their final destination.
    • Proteins destined for the interior of peroxisomes, mitochondria, and chloroplasts are synthesized on cytosolic ribosomes, may fold partially, and are then unfolded for transport across the membrane.

    Vesicular Trafficking

    • Vesicles, small closed bags of membrane, carry newly synthesized proteins from the endoplasmic reticulum to the Golgi apparatus and between other compartments.
    • The fate of a protein, whether to remain in the cytosol or be transported via an alternative path, is determined by sorting signals within the protein itself.

    Targeting Sequences

    • Initial sorting decisions are made based on particular amino acid sequences called targeting sequences.
    • For proteins synthesized on the rough endoplasmic reticulum, additional sorting signals such as sugars and phosphate groups can be added by enzymes that modify the protein's chemical structure.

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    Description

    Learn about the two main mechanisms of protein transport: gated transport and transmembrane translocation. Understand how proteins move to their final destinations in the cell.

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