Cell Membrane Structure and Function
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Questions and Answers

What is the primary structural component of the cell membrane?

  • Glycoprotein
  • Phospholipid bilayer (correct)
  • Hydrophobic tail
  • Carbohydrate chain

Which component of the cell membrane is responsible for cell-cell recognition?

  • External surface membrane
  • Hydrophobic tail
  • Internal surface membrane
  • Glycolipid (correct)

What is the main energy requirement for active transport?

  • It requires light energy.
  • It does not require any energy.
  • It requires chemical energy from glucose.
  • It requires cellular energy in the form of ATP. (correct)

Where are the hydrophilic heads of phospholipids oriented in the cell membrane?

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

Which process is involved in the ingestion of large particles by cells?

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

During facilitated diffusion, materials pass through what?

<p>Transport proteins (C)</p> Signup and view all the answers

What type of molecules can perform diverse functions such as transport within the cell membrane?

<p>Protein molecules (C)</p> Signup and view all the answers

Which component of the membrane is not directly part of the phospholipid bilayer?

<p>External surface membrane (A)</p> Signup and view all the answers

What distinguishes simple diffusion from facilitated diffusion?

<p>Simple diffusion involves small, non-polar molecules. (D)</p> Signup and view all the answers

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

<p>To establish an ion concentration gradient. (D)</p> Signup and view all the answers

Which of the following statements accurately describes the role of the cell membrane?

<p>It selectively controls what enters and leaves the cell. (A)</p> Signup and view all the answers

What is primarily responsible for the flexibility of the cell membrane?

<p>Phospholipid bilayer arrangement (D)</p> Signup and view all the answers

Which factor does NOT affect the rate of diffusion across the cell membrane?

<p>Color of the molecules (D)</p> Signup and view all the answers

How do non-polar molecules primarily travel through the cell membrane?

<p>By dissolving in the hydrophobic interior (C)</p> Signup and view all the answers

What happens to a cell placed in a hypertonic solution?

<p>The cell shrinks and may undergo plasmolysis. (D)</p> Signup and view all the answers

Which type of molecules can pass through a selectively permeable membrane most easily?

<p>Small non-polar molecules (B)</p> Signup and view all the answers

What is the primary direction of water movement during osmosis?

<p>From low solute concentration to high solute concentration (A)</p> Signup and view all the answers

What effect does temperature have on the rate of diffusion?

<p>Increased temperature generally increases the rate of diffusion. (B)</p> Signup and view all the answers

Which statement about the fluid mosaic model is true?

<p>It describes a dynamic structure of various components. (A)</p> Signup and view all the answers

What characteristic of a semi-permeable membrane is essential for maintaining homeostasis?

<p>It selectively permits certain molecules to cross. (A)</p> Signup and view all the answers

Flashcards

Phospholipid bilayer

A double layer of phospholipids that forms the primary structure of the cell membrane.

Hydrophilic head

The water-loving head of a phospholipid molecule, oriented towards the watery environment both inside and outside the cell.

Hydrophobic tail

The water-fearing tail of a phospholipid molecule, oriented inward, away from the watery environment.

Membrane proteins

Proteins embedded within the phospholipid bilayer, performing diverse functions like transport and enzymatic activity.

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Glycolipids

Lipid molecules with a carbohydrate chain attached, found on the external surface of the cell membrane, often involved in cell-cell recognition and signaling.

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Simple Diffusion

Movement of molecules from an area of high concentration to an area of low concentration across a membrane without requiring energy.

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Facilitated Diffusion

Movement of molecules across a membrane with the help of a transport protein, moving from high to low concentration. Doesn't require energy.

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Active Transport

Movement of molecules across a membrane against the concentration gradient (from low to high concentration), requiring energy (ATP).

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Exocytosis

Process by which cells move materials out of the cell using membrane-bound vesicles that fuse with the cell membrane and release their contents.

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Endocytosis

Process by which cells move materials into the cell by engulfing them in a portion of the cell membrane which pinches off to form a vesicle.

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Cell Membrane

The structure that surrounds a cell, regulating what enters and exits. It's a phospholipid bilayer with hydrophilic heads and hydrophobic tails.

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Diffusion

The movement of molecules across a membrane from an area of high concentration to an area of low concentration.

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Selectively Permeable Membrane

A membrane that allows some molecules to pass through but not others.

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Non-polar Molecule

A non-polar molecule like a fatty acid, easily passing through the cell's hydrophobic interior.

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Polar Molecule

A polar molecule like water or an ion. These molecules struggle to pass through the non-polar cell membrane.

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Osmosis

The movement of water across a membrane from a region of low solute concentration to a region of high solute concentration.

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Hypotonic Solution

A solution where the solute concentration is lower outside the cell than inside.

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Isotonic Solution

A solution where the solute concentration is equal inside and outside the cell.

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Hypertonic Solution

A solution where the solute concentration is higher outside the cell than inside.

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Homeostasis

The state where the cell maintains a stable internal environment.

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