Transport Across the Cell Membrane L4
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Questions and Answers

What is the structure of the human cell membrane?

The human cell membrane is made of a phospholipid bilayer.

Define membrane permeability.

Membrane permeability is the ease with which substances can pass through the cell membrane.

What are the types of membrane channels?

  • Leak channels
  • Voltage-gated channels
  • Ligand-gated channels
  • All of the above (correct)

    • What is passive transport?

    <p>Does not require energy</p> Signup and view all the answers

    Simple diffusion transports substances from areas of high concentration to areas of ______.

    <p>low concentration</p> Signup and view all the answers

    Match the types of membrane transport with their characteristics:

    <p>Simple diffusion = Movement along the concentration gradient without energy Facilitated diffusion = Transport via carrier proteins Primary active transport = Direct use of ATP to transport substances Secondary active transport = Indirectly uses ATP by relying on primary transport processes</p> Signup and view all the answers

    What influences the rate of simple diffusion?

    <p>The chemical concentration difference, molecular size, and number of open channels.</p> Signup and view all the answers

    Which substances can pass directly through the lipid bilayer?

    <p>Fat-soluble substances</p> Signup and view all the answers

    What is the structure of the human cell membrane?

    <p>A phospholipid bilayer (double layer)</p> Signup and view all the answers

    The cell membrane is freely permeable to all substances.

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

    Define membrane permeability.

    <p>The ease with which substances can pass through the cell membrane.</p> Signup and view all the answers

    Which of the following is NOT a type of membrane transport?

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

    The cell membrane is freely permeable to all substances.

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

    What type of channels open by changes in electrical charge?

    <p>Voltage-gated channels</p> Signup and view all the answers

    What does osmosis refer to?

    <p>The movement of water across a semipermeable membrane.</p> Signup and view all the answers

    Transport that does not require energy is known as ______ transport.

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

    What role do integral proteins play in the cell membrane?

    <p>They provide structural integrity and facilitate transport.</p> Signup and view all the answers

    Match the types of membrane transport to their characteristics:

    <p>Simple diffusion = Movement along concentration gradient without energy Facilitated diffusion = Use of proteins to help transport water-soluble substances Primary active transport = Direct use of ATP to transport substances against gradient Secondary active transport = Utilizes energy from other processes to move substances</p> Signup and view all the answers

    Which substances can pass directly through the lipid bilayer?

    <p>Fat-soluble substances</p> Signup and view all the answers

    What is the effect of the concentration difference on diffusion rate?

    <p>The bigger the concentration difference, the faster the diffusion rate.</p> Signup and view all the answers

    Study Notes

    Structure of the Cell Membrane

    • Composed of a phospholipid bilayer featuring hydrophilic heads and hydrophobic tails.
    • Hydrophilic heads orient toward the aqueous environment, while hydrophobic tails face inward, creating a barrier that restricts water and water-soluble ions' passage.
    • Integral proteins span the membrane, contributing to structural integrity and facilitating transport.

    Membrane Protein Functions

    • Channel Proteins: Provide pathways for the diffusion of water-soluble substances, such as glucose and electrolytes.
    • Carrier Proteins: Assist in the transport of specific molecules across the membrane.
    • Receptor Proteins: Serve as binding sites for hormones and neurotransmitters, facilitating cellular communication.
    • Enzymatic Proteins: Catalyze chemical reactions that occur at the membrane surface.

    Membrane Transport Definitions

    • Cell-membrane transport: Mechanisms regulating the passage of solutes and molecules across the membrane.
    • Permeability: Indicates how easily substances pass through the membrane; characterized as impermeable, freely permeable, or selectively permeable.

    Types of Membrane Channels

    • Leak Channels (Pores): Continuously open, allowing substances to pass freely.
    • Voltage-gated Channels: Open in response to changes in membrane potential.
    • Ligand-gated Channels: Activated by binding to specific molecules, such as neurotransmitters.

    Mechanisms of Transport

    • Directly through Lipid Bilayer: Fat-soluble substances (e.g., O2, CO2) diffuse through the bilayer directly.
    • Through Protein Channels: Water-soluble substances (e.g., glucose, iron) utilize protein channels for transport.

    Types of Membrane Transport

    • Passive Transport:

      • Simple Diffusion: Movement along the concentration gradient without energy expenditure.
      • Facilitated Diffusion: Involves carrier proteins to assist diffusion.
      • Osmosis: Diffusion of water across a selectively permeable membrane.

    • Active Transport:

      • Primary Active Transport: Directly uses ATP to move substances against their concentration gradient.
      • Secondary Active Transport: Relies on the energy from primary transport to move additional substances.
      • Vesicular Transport: Includes exocytosis and endocytosis for transporting large volumes or particles.

    Factors Influencing Simple Diffusion

    • Concentration Gradient: Greater differences in concentration between two sides of the membrane increase the diffusion rate.
    • Molecular Size: Smaller molecules diffuse more easily than larger ones.
    • Number of Open Channels: More available channels enhance the diffusion rate, such as sodium channels activated by acetylcholine at neuromuscular junctions.

    Structure of the Cell Membrane

    • Composed of a phospholipid bilayer featuring hydrophilic heads and hydrophobic tails.
    • Hydrophilic heads orient toward the aqueous environment, while hydrophobic tails face inward, creating a barrier that restricts water and water-soluble ions' passage.
    • Integral proteins span the membrane, contributing to structural integrity and facilitating transport.

    Membrane Protein Functions

    • Channel Proteins: Provide pathways for the diffusion of water-soluble substances, such as glucose and electrolytes.
    • Carrier Proteins: Assist in the transport of specific molecules across the membrane.
    • Receptor Proteins: Serve as binding sites for hormones and neurotransmitters, facilitating cellular communication.
    • Enzymatic Proteins: Catalyze chemical reactions that occur at the membrane surface.

    Membrane Transport Definitions

    • Cell-membrane transport: Mechanisms regulating the passage of solutes and molecules across the membrane.
    • Permeability: Indicates how easily substances pass through the membrane; characterized as impermeable, freely permeable, or selectively permeable.

    Types of Membrane Channels

    • Leak Channels (Pores): Continuously open, allowing substances to pass freely.
    • Voltage-gated Channels: Open in response to changes in membrane potential.
    • Ligand-gated Channels: Activated by binding to specific molecules, such as neurotransmitters.

    Mechanisms of Transport

    • Directly through Lipid Bilayer: Fat-soluble substances (e.g., O2, CO2) diffuse through the bilayer directly.
    • Through Protein Channels: Water-soluble substances (e.g., glucose, iron) utilize protein channels for transport.

    Types of Membrane Transport

    • Passive Transport:

      • Simple Diffusion: Movement along the concentration gradient without energy expenditure.
      • Facilitated Diffusion: Involves carrier proteins to assist diffusion.
      • Osmosis: Diffusion of water across a selectively permeable membrane.

    • Active Transport:

      • Primary Active Transport: Directly uses ATP to move substances against their concentration gradient.
      • Secondary Active Transport: Relies on the energy from primary transport to move additional substances.
      • Vesicular Transport: Includes exocytosis and endocytosis for transporting large volumes or particles.

    Factors Influencing Simple Diffusion

    • Concentration Gradient: Greater differences in concentration between two sides of the membrane increase the diffusion rate.
    • Molecular Size: Smaller molecules diffuse more easily than larger ones.
    • Number of Open Channels: More available channels enhance the diffusion rate, such as sodium channels activated by acetylcholine at neuromuscular junctions.

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    Related Documents

    Transport Across the Cell Membrane PDF
    Cell Membrane Transport PDF

    Description

    This quiz focuses on the transport mechanisms across the human cell membrane. Students will explore membrane permeability, types of membrane channels, and understand the processes involved in simple diffusion and more. It's designed for those studying medical physiology.

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