Cell Biology: 1.3M Transportation of Substances through the cell
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Questions and Answers

Lipid soluble substances can move through the lipid bilayer.

True (A)

Which of the following molecules is more lipid soluble than oxygen?

  • CO2 (correct)
  • Water
  • Sodium (Na+)
  • Glucose

    • The rate of diffusion of lipid soluble substances is directly proportional to their ______.

    lipid solubility

    What type of protein channels allow water to pass through the cell membrane?

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

    Which of the following statements is TRUE about aquaporins?

    <p>They allow water to pass through the membrane at an extremely fast rate. (D)</p> Signup and view all the answers

    Match the following types of membrane channels with their regulation:

    <p>Ligand-gated channels = Chemicals binding to the channel Voltage-gated channels = Electrical signals</p> Signup and view all the answers

    What is the main difference between pores and protein channels in the cell membrane?

    <p>Pores are always open, while protein channels can open or close by gates.</p> Signup and view all the answers

    Charged ions are generally lipid soluble and can easily pass through the lipid bilayer.

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

    Molecular movement is constant and occurs only in one direction.

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

    Which of the following factors directly influences the net diffusion rate across a semi-permeable membrane?

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

    The ______ equation is used to calculate the balance between the electrical gradient and the concentration gradient.

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

    What is osmotic pressure?

    <p>Osmotic pressure is the pressure required to stop osmosis.</p> Signup and view all the answers

    Match the following terms related to osmosis with their definitions:

    <p>Osmosis = The movement of water molecules across a semi-permeable membrane from an area of high water concentration to an area of low water concentration. Osmotic pressure = The pressure required to prevent the inward flow of water across a semi-permeable membrane Osmolality = The concentration of a solution in terms of the number of particles per unit mass of solvent Osmole = One gram molecular weight of osmotic active solute</p> Signup and view all the answers

    Which of the following is NOT a factor that affects the net diffusion rate across a semi-permeable membrane?

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

    What is the normal osmolality of extracellular and intracellular fluids?

    <p>300 milliosmoles per kg of water</p> Signup and view all the answers

    The osmolality of a solution is always equal to its osmotic pressure.

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

    Secondary active transport utilizes the potential energy stored from primary active transport to move substances across the cell membrane.

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

    What is the primary mechanism responsible for the large concentration gradient of sodium ions across the cell membrane?

    <p>Primary Active Transport (A)</p> Signup and view all the answers

    Explain how co-transport (symport) functions in secondary active transport.

    <p>In co-transport, a carrier protein binds both sodium ions and another substance. The movement of sodium down its concentration gradient provides the energy to move both substances into the cell.</p> Signup and view all the answers

    The ______ of the sodium ions outside the cell is constantly attempting to move into the interior due to the concentration gradient.

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

    Which of the following is NOT an example of a cellular sheet where secondary active transport plays a role in substance transport?

    <p>Skeletal muscle cells (C)</p> Signup and view all the answers

    Match the following types of secondary active transport with their respective examples:

    <p>Co-transport (symport) = Sodium and glucose transport Counter-transport (antiport) = Sodium and hydrogen ion transport</p> Signup and view all the answers

    Describe how the active transport of sodium ions at the basal and lateral membranes of cellular sheets contributes to water transport across the entire sheet.

    <p>The active transport of sodium ions out of the cell creates a high concentration of sodium in the extracellular fluid. This concentration gradient drives osmosis of water from the cell into the extracellular fluid.</p> Signup and view all the answers

    Counter-transport (antiport) is a more powerful mechanism than primary active transport in concentrating substances.

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

    Which characteristics affect ion channel permeability?

    <p>All of the above (D)</p> Signup and view all the answers

    Potassium ions can pass through potassium channels 1000 times more readily than sodium ions.

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

    What is the role of the selectivity filter in ion channels?

    <p>To allow specific ions to pass while blocking others.</p> Signup and view all the answers

    The process that allows substances to diffuse across a membrane with the help of carrier proteins is known as ________ diffusion.

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

    Match the following types of gating with their descriptions:

    <p>Voltage gated = Responds to electrical potential across the membrane Chemical (ligand) gated = Responds to a chemical substance binding Acetylcholine receptor = Allows uncharged or positive particles smaller than 0.65 nm to pass</p> Signup and view all the answers

    What is Vmax in relation to carrier proteins?

    <p>Maximum rate of diffusion. (D)</p> Signup and view all the answers

    Chemical gating involves a conformational change caused solely by voltage changes.

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

    What type of ions does the acetylcholine receptor primarily allow to pass?

    <p>Uncharged or positive particles smaller than 0.65 nm.</p> Signup and view all the answers

    What is the primary function of the sodium-potassium pump?

    <p>To maintain concentration differences of sodium and potassium ions (D)</p> Signup and view all the answers

    Osmolarity and osmolality refer to the same concept.

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

    What is the concentration of potassium ions inside the cell in mEq/L?

    <p>140</p> Signup and view all the answers

    The process of moving ions against their concentration gradient requires __________ energy.

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

    Match the type of transport with their definitions:

    <p>Primary Active Transport = Directly uses energy from ATP breakdown Secondary Active Transport = Uses stored energy from ionic concentration differences Osmolarity = Osmole concentration per liter of solution Osmolality = Osmole concentration per kilogram of solution</p> Signup and view all the answers

    What type of transport is associated with the sodium-potassium pump?

    <p>Primary Active Transport (A)</p> Signup and view all the answers

    Sodium ions have a higher concentration inside the cell compared to outside.

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

    What happens to the sodium and potassium ions during the operation of the sodium-potassium pump?

    <p>Three sodium ions are expelled outside the cell, and two potassium ions are brought inside.</p> Signup and view all the answers

    What is the primary function of the sodium-potassium pump in cells?

    <p>To control cell volume (B)</p> Signup and view all the answers

    The sodium-potassium pump pumps 3 potassium ions into the cell for every 2 sodium ions pumped out.

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

    What creates the electrical potential across the cell membrane?

    <p>Net loss of 1+ ion due to sodium-potassium pump activity</p> Signup and view all the answers

    Calcium is maintained at extremely low intracellular concentrations, with _____ MEQ outside versus _____ MEQ inside.

    <p>2.4, 0.001</p> Signup and view all the answers

    What primary role does the hydrogen ion transport serve in the stomach?

    <p>Secretion of hydrochloric acid (D)</p> Signup and view all the answers

    The sodium-potassium pump functions independently of ATP.

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

    What are the two primary locations to which calcium is transported in muscle cells?

    <p>Sarcoplasmic reticulum and mitochondria</p> Signup and view all the answers

    Match the ion with its primary active transport role:

    <p>Sodium = Controls cell volume Potassium = Creates intracellular negativity Calcium = Regulates muscle function Hydrogen = Secretes gastric acid</p> Signup and view all the answers

    Study Notes

    Motile Cilia

    • Rapid whip-like strokes propel mucus and ova.
    • Recovery movements are slower (10-20 per second).
    • Inhibited by smoking.
    • Found in respiratory airways (mucus movement) and fallopian tubes (ovum movement).
    • Powered by dynein motor proteins and ATP.

    Non-Motile Cilia

    • Primary cilia act as sensory structures (e.g., kidney epithelial cells detecting fluid flow).
    • Defects in primary cilia signaling can lead to disorders like polycystic kidney disease (pg. 28 Guyton).

    Key Concepts

    • Chemotaxis: Chemical signals direct cell movement.
    • Autophagy: Cellular process to degrade and recycle damaged organelles or protein aggregates.
    • ATP: Primary energy currency for cellular processes.
    • Plasma membrane: Selectively permeable barrier maintaining cellular homeostasis.

    Transport of Substances Through Cell Membranes

    • Intracellular and extracellular fluid concentration differences are crucial for cell function.
    • Extracellular fluid has high sodium and chloride, but low potassium.
    • Intracellular fluid has high potassium and low sodium and chloride.

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    Explore the fascinating world of cilia with this quiz on motile and non-motile types. Learn about their roles in transport, signaling, and implications for health. Test your understanding of essential concepts related to cellular processes and membrane transport.

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