L2-Cell Membrane structure and transport proteins
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Questions and Answers

What is the direction of solute movement described?

  • Inside the cell (correct)
  • Between cells
  • Outside the cell
  • Across the membrane

    • Which transport mechanism involves the movement of two different solutes in the same direction?

  • Osmosis
  • Passive transport
  • Co transport (correct)
  • Countertransport

    • Does primary active transport of calcium contribute to a high concentration of Ca2+ inside the cell?

  • Only during specific conditions
  • No, it does not
  • Yes, it does (correct)
  • It is irrelevant to calcium concentration

    • Which of the following requires energy for solute transport?

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

    Which of these statements about calcium transport is false?

    <p>It functions solely via passive mechanisms</p> Signup and view all the answers

    Which of the following describes simple diffusion?

    <p>Passive movement of molecules across a membrane without the aid of proteins.</p> Signup and view all the answers

    What characterizes primary active transport?

    <p>It utilizes ATP to move substances against their concentration gradient.</p> Signup and view all the answers

    Which process is specifically associated with the movement of water?

    <p>Osmosis.</p> Signup and view all the answers

    What is a key difference between facilitated diffusion and simple diffusion?

    <p>Facilitated diffusion requires specific transport proteins.</p> Signup and view all the answers

    Which option is NOT a type of membrane transport mentioned?

    <p>Secondary active transport.</p> Signup and view all the answers

    Which statement accurately describes the cell membrane?

    <p>It functions as a fluid barrier that covers the cell.</p> Signup and view all the answers

    What percentage of the cell membrane's composition is made up of proteins?

    <p>55%</p> Signup and view all the answers

    Which component of the cell membrane is characterized by having a hydrophilic head and two hydrophobic tails?

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

    What role do integral proteins play in the cell membrane?

    <p>They span the whole thickness of the membrane and form channels.</p> Signup and view all the answers

    Which of the following best describes glycolipids in the cell membrane?

    <p>They are primarily carbohydrates bound to lipid molecules.</p> Signup and view all the answers

    The term 'amphipathic' in relation to cell membranes refers to which of the following features?

    <p>Combination of hydrophilic heads and hydrophobic tails.</p> Signup and view all the answers

    Which type of protein is associated with the cell membrane but does not span the membrane's full thickness?

    <p>Peripheral proteins</p> Signup and view all the answers

    What is the primary function of glycoproteins in the cell membrane?

    <p>To serve as receptors and cell surface antigens.</p> Signup and view all the answers

    What process allows substances to move across a membrane without the expenditure of energy?

    <p>Simple diffusion</p> Signup and view all the answers

    Which option describes the process that selectively moves water across a membrane?

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

    Which of the following processes requires energy to move substances across a membrane?

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

    Facilitated diffusion is best characterized by which of the following?

    <p>Movement of molecules with the help of a protein channel</p> Signup and view all the answers

    Which process is primarily responsible for the transport of ions across cell membranes?

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

    What is the main role of the Na+/K+-ATPase pump in a cell?

    <p>To maintain a normal cell volume</p> Signup and view all the answers

    How many sodium ions are typically transported out of the cell by the Na+/K+-ATPase pump?

    <p>3 Na ions</p> Signup and view all the answers

    Which of the following was the significant contribution of Jens Christian Skou in 1957?

    <p>Discovered the Na+/K+-ATPase pump</p> Signup and view all the answers

    What happens when the Na+/K+-ATPase pump is inhibited?

    <p>Sodium ions accumulate inside the cell</p> Signup and view all the answers

    What is the typical ratio of potassium ions transported into the cell by the Na+/K+-ATPase pump?

    <p>2 K ions</p> Signup and view all the answers

    Study Notes

    Characteristics of Cell Membrane

    • Covers the cell, providing protection and structure.
    • Thin, pliable, and elastic, measuring 7-10 nanometers.
    • Exists in a fluid state, referred to as the plasma membrane.

    Composition of Cell Membrane

    • Proteins: 55% of the membrane's structure.
    • Lipids: 42% total, including:
      • Phospholipids: 25%
      • Cholesterol: 13%
      • Glycolipids: 4%
    • Carbohydrates: Comprise 3% of the membrane.

    Phospholipid Structure

    • Comprised of:
      • Glycerol head: Hydrophilic (water-attracting)
      • Two fatty acid tails: Hydrophobic (water-repelling)
    • Heads face the intracellular fluid (ICF) and extracellular fluid (ECF), while tails face each other, forming a bilayer.
    • This dual nature makes phospholipids amphipathic.

    Cell Membrane Proteins

    • Integral Proteins:

      • Span the entire membrane thickness.
      • Function as structural channels or pores.

    • Peripheral Proteins:

      • Located on one side of the membrane.
      • Function as hormone receptors and cell surface antigens.

    Cell Membrane Carbohydrates

    • Glycoproteins: Mostly carbohydrate-bound proteins.
    • Glycolipids: Mainly carbohydrates, forming the outer layer.
    • Proteoglycans: Comprise carbohydrate molecules that protrude outward, creating a loose carbohydrate coat called glycoalyx.

    Types of Membrane Transport

    • Diffusion:

      • Simple diffusion: Movement of molecules from high to low concentration.
      • Facilitated diffusion: The process utilizes carrier proteins for molecule transport.

    • Active Transport:

      • Primary active transport: Requires energy to move molecules against their concentration gradient.

    • Osmosis: Movement of water across the membrane.

    Transport Mechanisms

    • All solutes can move toward the cell interior.

    • Osmosis, Co-transport, Countertransport, and Passive transport are key mechanisms in cell transport.

    • Primary active transport maintains a high calcium concentration inside the cell.

    Key Discovery

    • The Na+/K+-ATPase pump was discovered by Jens Christian Skou in 1957, crucial for maintaining cellular ion balance.

    Multiple Choice Questions

    • Active transport is the transport mechanism that requires energy.
    • The process of selective movement in and out of the membrane involves moving 3 Na+ out and 2 K+ in, maintaining normal cell volume.

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    Related Documents

    Cell Membrane Structure and Transport Across Cell Membrane PDF

    Description

    Explore the essential characteristics and composition of the cell membrane in this quiz. Learn about the fluid nature, the various components such as proteins, lipids, and carbohydrates that make up the plasma membrane. Test your knowledge on the significance of each of these components.

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