2.1 - BIOLOGICAL MEMBRANES AND TRANSPORT
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Questions and Answers

Which disease is directly related to the malfunction of the CFTR gene?

  • Cerebral Degeneration
  • Menkes Disease
  • Cystic Fibrosis (correct)
  • Wilson’s Disease

What is the primary function of copper transporting P-ATPases in the body?

  • Absorption of copper into the system (correct)
  • Detoxification of harmful substances
  • Assisting in chloride ion transport
  • Regulating c-AMP levels

Which of the following conditions can result from excessive copper accumulation due to the malfunction of copper ATPases?

  • Aneurysm formation
  • Cystic Fibrosis
  • Severe copper deficiency
  • Cirrhosis (correct)

In the context of ABC transporters, what does overexpression typically lead to in cancer treatment?

<p>Development of multidrug resistance (A)</p> Signup and view all the answers

Which of the following describes a key feature of the CFTR protein?

<p>Acts as a chloride ion channel (A)</p> Signup and view all the answers

Which of the following is NOT a characteristic of peripheral membrane proteins?

<p>They can form transmembrane domains. (B)</p> Signup and view all the answers

Which lipid contributes to changes in membrane shape and can play key roles in both fusion and fission of membranes?

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

Which of the following is a characteristic of lipid rafts?

<p>They are involved in various functions, including cell signaling and transport. (D)</p> Signup and view all the answers

Which of the following statements about integral membrane proteins is TRUE?

<p>They can have both hydrophobic and hydrophilic domains. (D)</p> Signup and view all the answers

Which of the following is NOT a characteristic of active transport?

<p>It is driven by the electrochemical gradient. (C)</p> Signup and view all the answers

Which of the following is NOT a characteristic of facilitated diffusion?

<p>It requires energy input. (A)</p> Signup and view all the answers

Which of the following molecules can influence the fluidity and permeability of a membrane?

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

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

<p>Production of ATP (C)</p> Signup and view all the answers

Why is the exoplasmic leaflet of a cell membrane considered different from the cytoplasmic leaflet?

<p>The exoplasmic leaflet has a different lipid composition compared to the cytoplasmic leaflet. (C)</p> Signup and view all the answers

Which of the following statements accurately describes the role of cholesterol in biological membranes?

<p>Cholesterol increases membrane fluidity by disrupting the tight packing of phospholipids. (B)</p> Signup and view all the answers

Lipid rafts, microdomains within cell membranes, are characterized by which of the following features?

<p>They are enriched in sphingolipids and cholesterol, leading to a more ordered structure. (C)</p> Signup and view all the answers

How does the presence of an electrochemical gradient influence the movement of ions across a biological membrane?

<p>It creates a favorable condition for passive transport, but actively transported ions move against the gradient. (B)</p> Signup and view all the answers

What is the primary function of ATPases?

<p>To drive ion movement using ATP (D)</p> Signup and view all the answers

Which of the following correctly describes the relationship between membrane fluidity and lipid composition?

<p>The presence of phospholipids with unsaturated fatty acids increases membrane fluidity, due to the kinks in their tails. (D)</p> Signup and view all the answers

What is the primary difference between simple diffusion and facilitated diffusion?

<p>Simple diffusion does not require a transporter protein, while facilitated diffusion does. (C)</p> Signup and view all the answers

Which ATPase is specifically associated with calcium sequestration in the sarcoplasmic reticulum?

<p>Ca2+ ATPase (B)</p> Signup and view all the answers

What distinguishes secondary active transport from primary active transport?

<p>Primary transport uses ATP, while secondary does not. (A)</p> Signup and view all the answers

Which of the following conditions would promote the development of a resting membrane potential?

<p>A higher concentration of potassium ions outside the cell, compared to the inside. (A)</p> Signup and view all the answers

Which of the following ATPases plays a role in the acidification of the stomach?

<p>H+/K+ ATPase (C)</p> Signup and view all the answers

In the context of membrane transport, which of the following correctly describes the 'saturation' of transport?

<p>The maximum rate of transport that can be achieved by a transporter protein, at which all transporter molecules are occupied. (D)</p> Signup and view all the answers

In which cellular structure is the F-ATPase primarily involved?

<p>Coupling factor involvement in various cellular activities (A)</p> Signup and view all the answers

Which of the following diseases is directly linked to a defect in membrane structure, specifically involving a protein responsible for chloride ion transport?

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

What role does Na+/K+ ATPase primarily serve in cellular processes?

<p>Maintaining resting membrane potential (D)</p> Signup and view all the answers

Where is the v-type ATPase most abundantly found?

<p>In endosomal and lysosomal membranes (D)</p> Signup and view all the answers

What is the significance of the electrochemical gradient in secondary active transport?

<p>It powers the movement of ions against their concentration gradients. (A)</p> Signup and view all the answers

Which ion is primarily excreted from the cell by Ca2+ ATPase?

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

Which of the following best describes the mechanism by which ATPase functions?

<p>By hydrolyzing ATP to provide energy for ion transport (A)</p> Signup and view all the answers

What initiates the action potential in excitable cells?

<p>Mass influx of sodium ions (B)</p> Signup and view all the answers

Which transporter has the lowest Kt for d-glucose?

<p>GLUT-1 (A)</p> Signup and view all the answers

Which of the following transport types requires energy?

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

What role do ion transport pumps play in maintaining resting potential?

<p>Creating a differential ion gradient (C)</p> Signup and view all the answers

Which GLUT transporter is primarily responsible for fructose transport?

<p>GLUT-5 (B)</p> Signup and view all the answers

Which ATPase is specifically associated with ATP synthesis driven by an electrochemical gradient?

<p>F-ATPase (D)</p> Signup and view all the answers

What is the function of the SGLT-1 transporter?

<p>Transports glucose using Na+ ions (C)</p> Signup and view all the answers

Which of the following statements about resting potential is true?

<p>It requires energy to maintain the differential ion gradient. (C)</p> Signup and view all the answers

Which cells primarily utilize GLUT-4 for glucose uptake?

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

Which mechanism is responsible for the accumulation of H+ ions in lysosomal membranes?

<p>V-ATPase (B)</p> Signup and view all the answers

Flashcards

Biological Membrane Structure

A biological membrane consists of a lipid bilayer with embedded proteins, serving as a barrier between environments.

Passive Transport

The movement of molecules across a membrane without energy input, driven by concentration gradients.

Active Transport

The process of moving molecules against a concentration gradient, requiring energy (usually ATP).

Ionophores

Molecules that facilitate the transport of ions across membranes by creating a pathway.

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Lipid Rafts

Microdomains in the membrane rich in cholesterol and certain lipids, playing a key role in cell signaling.

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Diffusion Kinetics

The study of how molecules spread from areas of high to low concentration, affecting transport speed and efficiency.

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Electrochemical Gradient

A difference in charge and concentration across a membrane, crucial for processes like nerve impulses.

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Resting and Action Potentials

Resting potential is the stable state of a neuron, while action potential is a rapid change in membrane potential during signaling.

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P-ATPases

Enzymes that transport ions and molecules across membranes using ATP.

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ABC Transporters

Transport proteins that use ATP to move substances across membranes; involved in drug resistance.

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CFTR

Chloride ion channel regulated by phosphorylation; mutations cause cystic fibrosis.

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Menkes Disease

Genetic disorder leading to copper deficiency due to a defect in copper ATPase.

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Wilson’s Disease

Build-up of toxic copper in the body due to improper copper transport.

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Biological Membrane Functions

Regulates entry of nutrients, excretion of waste, and cellular communication.

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Integral Membrane Proteins

Proteins permanently embedded in membranes, often forming channels or receptors.

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Peripheral Membrane Proteins

Proteins that temporarily attach to membranes through various interactions.

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Phospholipids

Lipids with hydrophobic tails and polar heads that form the backbone of membranes.

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Facilitated Diffusion

Process where proteins help transport substances quicker than simple diffusion, but with saturation limits.

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Sphingolipids

A class of lipids that are more saturated, providing density and rigidity to membranes.

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Cholesterol

A sterol that stabilizes membrane fluidity and reduces permeability.

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ATPase

An enzyme that catalyzes the hydrolysis of ATP to ADP, releasing energy for cellular processes.

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Primary Active Transport

Transport that directly uses energy from ATP to move ions against their gradient.

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Secondary Active Transport

Transport coupled with the movement of another substance down its electrochemical gradient.

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Ca2+ ATPase

An ATPase that pumps calcium ions out of the cell or into the sarcoplasmic reticulum.

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V-type ATPase

A vacuolar ATPase that pumps protons into vacuoles, maintaining acidic environments.

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F-ATPase Coupling Factor

A protein that assists in ATP synthesis by coupling proton transport to ATP production.

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H+/K+ ATPase

An enzyme in the gastric parietal cells that exchanges potassium ions for protons, aiding in stomach acid production.

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Calcium Sequestration

The process by which calcium ions are stored in the sarcoplasmic reticulum for later use.

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Ion Pump

A type of membrane protein that moves ions across a biological membrane against their concentration gradient.

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Resting Potential

The stable, inactive state of excitable cells characterized by a differential gradient between sodium and potassium ions.

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Action Potential

Rapid changes in membrane polarity, initiated when threshold potential is reached, causing a mass influx of sodium ions.

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Threshold Potential

The critical level to which a membrane potential must be depolarized to initiate an action potential.

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GLUT Transporters

Group of transport proteins that facilitate the passive transport of glucose and other sugars across cell membranes.

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SGLT Transporters

Sodium-coupled glucose transporters that use the sodium gradient to drive glucose uptake against its concentration gradient.

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Ion Transport Pumps

Proteins in cell membranes that actively transport ions to maintain gradients, critical for resting potential.

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Study Notes

Biological Membranes and Transport

  • Biological membranes are fundamental structures, crucial for regulating cell function.
  • Membrane components (lipids, proteins, cholesterol) influence fluidity and barrier function.
  • Changes in membrane components can have significant consequences.
  • Cholesterol plays a critical role in maintaining membrane fluidity and stability.
  • Lipids are essential for defining membrane structure and function.
  • Various membrane proteins (integral and peripheral) carry out vital functions like transport and catalysis.

Membrane Lipids: Shape and Fluidity

  • Lipids are essential for membrane structure, integrity, and signaling.
  • Lipid composition (types, length, number of double bonds, stereochemistry) dictates membrane fluidity and permeability.
  • Lipids exhibit asymmetry, differing between exoplasmic and cytoplasmic regions.
  • A huge range of lipids in mammalian cells contribute to unique biological roles and behaviors.

Membrane Proteins: Structure and Function

  • Membrane proteins perform diverse functions, crucial to cell signaling, transport, and other processes.
  • They display asymmetry, often concentrating at lipid rafts.
  • Proteins can be integral (transmembrane or monotopic), or peripheral.
  • Integral proteins are embedded, typically possessing combinations of hydrophobic and hydrophilic domains, which are required for membrane integration.

Lipid Rafts

  • Lipid rafts are membrane assemblies.
  • Enriched in sphingolipids, cholesterol, and saturated acyl side chains.
  • These regions display a variety of functions due to their protein content.
  • These regions play key roles in signaling, metabolic pathways, and cell transport.

Regulation of Membrane Domains

  • Membrane components, interacting with the cytoskeleton, produce complex regulation.
  • Docosahexaenoic acid (DHA) influences membrane raft composition.

Sphingolipids and Sphingomyelin

  • Sphingolipids are less prevalent than phospholipids.
  • They increase membrane density and rigidity.
  • Sphingomyelin is the most common sphingolipid, notable for its phosphocholine head group.

Cerebrosides and Gangliosides

  • Located on the exoplasmic leaflet, they are sphingolipids.
  • They are crucial for insulation in the nervous system, acting in cell-to-cell recognition pathways.
  • Cerebrosides attach to a monosaccharide, while gangliosides attach to more complex oligosaccharides.

Case Study 1: Parkinson's Disease

  • Lipids, particularly glucocerebroside (GBA), may play a role in Parkinson's Disease.
  • Genetic mutations in GBA contribute to altered lipid production, correlated with disease progression.

Cholesterol

  • Synthesized by all animal cells, cholesterol is a fundamental membrane component.
  • It affects membrane stability, regulates fluidity, and reduces permeability.
  • Cholesterol is a vital precursor for steroid hormones and bile salts.

Transport

  • Transport across cell membranes is vital.
  • Passive transport includes simple and facilitated diffusion.
  • Active transport requires energy, often moving molecules against electrochemical gradients.
  • Ions, and larger molecules like glucose, require specialized transporters and channels.

Chemical and Electrochemical Gradients

  • Differences in concentration generate gradients across cell membranes.
  • These electrochemical gradients regulate solute movement.
  • Gradients also play a fundamental role in cell function.

Action vs. Resting Potentials

  • Sensor proteins react to membrane polarity changes, triggering voltage-gated channels.
  • Resting potential is maintained by ion gradients and ion pumps.
  • Resting potentials are crucial in excitable cells.

Ionophores

  • Ionophores regulate movement across membranes, including antibiotics.
  • They often exhibit specificity for certain ions.
  • They impact membrane permeability.

Specificity and Saturability

  • Facilitated diffusion is more rapid than simple diffusion.
  • The rate of simple diffusion is directly proportional to substrate concentration.
  • Facilitated diffusion has a saturation point (Tmax).

Case Study 2: Cystic Fibrosis

  • Mutations in the CFTR gene cause cystic fibrosis.
  • CFTR is an ABC transporter with a chloride ion channel function, influencing chloride ion concentration in sweat.

Case Study 3: P-ATPases and Wilson's/Menkes Disease

  • P-ATPases play roles in copper absorption.
  • Menkes disease impacts copper absorption, leading to copper deficiency, and impacting several organs.
  • Wilson's disease disrupts copper excretion, resulting in toxic copper build-up in the liver and brain.

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Biological Membranes and Transport PDF

Description

Test your knowledge on biological membranes, their components, and the transport functions they facilitate. Understand how lipids, proteins, and cholesterol influence membrane fluidity and integrity in cellular contexts. This quiz covers essential concepts relevant to cellular biology and membrane dynamics.

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