Cell Membrane Structure and Function
20 Questions
2 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What structure is primarily responsible for the cell membrane's selective permeability?

  • Phosphate heads
  • Phospholipid bilayer (correct)
  • Lipid tails
  • Membrane proteins

In the fluid mosaic model, what does the term 'fluid' refer to?

  • The static nature of the cell membrane
  • The dynamic and flexible characteristics of membrane components (correct)
  • The rigid components of the membrane
  • The presence of water in the membrane

What is the main effect of placing a cell in a hypertonic solution?

  • The cell will swell
  • The cell will shrivel due to water loss (correct)
  • Water will move into the cell
  • The cell will remain unchanged

How does osmosis differ from diffusion?

<p>Osmosis is the diffusion of water across a semipermeable membrane (C)</p> Signup and view all the answers

What is likely to happen to a cell placed in a hypotonic solution?

<p>The cell will burst due to excess water intake (B)</p> Signup and view all the answers

Which type of solution results in equal concentrations of solutes inside and outside the cell?

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

What defines facilitated diffusion compared to simple diffusion?

<p>Facilitated diffusion relies on membrane proteins to help move substances (B)</p> Signup and view all the answers

Why do phosphate heads of phospholipids orient themselves towards water?

<p>They are hydrophilic (D)</p> Signup and view all the answers

What happens to water movement when a cell is placed in a hypertonic environment?

<p>Water is expelled from the cell into the environment (A)</p> Signup and view all the answers

What characterizes a semipermeable membrane?

<p>It selectively allows certain molecules to pass while blocking others (A)</p> Signup and view all the answers

What is the primary characteristic of the lipid tails in the phospholipid bilayer?

<p>Hydrophobic and water-repelling (C)</p> Signup and view all the answers

What occurs when a cell in a hypertonic solution loses water?

<p>The cell shrivels and may die (D)</p> Signup and view all the answers

Which of the following accurately describes osmosis?

<p>The diffusion of water across a semipermeable membrane (B)</p> Signup and view all the answers

How would a cell respond in a hypotonic environment?

<p>It would swell and possibly burst (B)</p> Signup and view all the answers

What does the term 'isotonic' indicate about a solution in relation to a cell?

<p>Equal solute concentration inside and outside the cell (C)</p> Signup and view all the answers

What role do phosphate heads play in the structure of cell membranes?

<p>Orienting themselves toward water due to their hydrophilic nature (B)</p> Signup and view all the answers

How do facilitated diffusion and simple diffusion primarily differ?

<p>Facilitated diffusion involves protein channels while simple diffusion does not (B)</p> Signup and view all the answers

What is the function of the semipermeable nature of cell membranes?

<p>To restrict movement of certain molecules while allowing others (D)</p> Signup and view all the answers

What accurately describes the term 'fluid' in the fluid mosaic model?

<p>The components can move freely within the layer (C)</p> Signup and view all the answers

Which factor can influence the movement of water across a semipermeable membrane?

<p>The concentration of solutes on either side of the membrane (C)</p> Signup and view all the answers

Flashcards

Phospholipid Bilayer

The cell membrane is composed of lipids and proteins that separate the cell's contents from the outside world. It's called a "bi-layer" because it has two layers of phospholipids arranged with their heads facing each other.

Phosphate Heads

The phosphate heads of phospholipids are hydrophilic, meaning they like water and orient themselves towards it.

Lipid Tails

The lipid tails of phospholipids are hydrophobic, meaning they fear water and face away from it.

Fluid Mosaic Model

This model describes the structure of the cell membrane more accurately than previous models. It's called "fluid" because the membrane is flexible and "mosaic" because it's made up of various components.

Signup and view all the flashcards

Semipermeable Membrane

Cell membranes are semipermeable, meaning they only allow certain substances to pass through. This is crucial for regulating what enters and leaves the cell.

Signup and view all the flashcards

Diffusion

The movement of liquid or gas molecules from an area of high concentration to an area of low concentration.

Signup and view all the flashcards

Osmosis

The diffusion of water across a semipermeable membrane. This is important for maintaining the water balance within cells.

Signup and view all the flashcards

Hypertonic Solution

This solution has a higher concentration of solutes than the cell. When a cell is placed in a hypertonic solution, water moves out of the cell, causing it to shrink.

Signup and view all the flashcards

Hypotonic Solution

This solution has a lower concentration of solutes than the cell. When a cell is placed in a hypotonic solution, water moves into the cell, causing it to swell potentially bursting.

Signup and view all the flashcards

Isotonic Solution

This is when the concentration of solutes is equal inside and outside of the cell. There is no net movement of water.

Signup and view all the flashcards

What is diffusion?

The movement of liquid or gas molecules from an area of high concentration to an area of low concentration.

Signup and view all the flashcards

What is osmosis?

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

Signup and view all the flashcards

Why does water move in osmosis?

The diffusion of water molecules across a selectively permeable membrane from an area of high water concentration to an area of low water concentration, driven by the difference in solute concentration.

Signup and view all the flashcards

What is a hypertonic solution?

A solution with a higher concentration of solutes than the cell inside it, causing water to move out of the cell.

Signup and view all the flashcards

What is a hypotonic solution?

A solution with a lower concentration of solutes than the cell inside it, causing water to move into the cell.

Signup and view all the flashcards

What is an isotonic solution?

A solution with the same concentration of solutes as the cell inside it, resulting in no net movement of water.

Signup and view all the flashcards

What is facilitated diffusion?

The process by which substances cross the cell membrane with the assistance of membrane proteins.

Signup and view all the flashcards

Why is the cell membrane called a phospholipid bilayer?

The cell membrane is composed of lipids and proteins that separate the cell's contents from the outside world. It's called a "bi-layer" because it has two layers of phospholipids arranged with their heads facing each other.

Signup and view all the flashcards

What are phosphate heads in the cell membrane?

The phosphate heads of phospholipids are hydrophilic, meaning they like water and orient themselves towards it.

Signup and view all the flashcards

What are lipid tails in the cell membrane?

The lipid tails of phospholipids are hydrophobic, meaning they fear water and face away from it.

Signup and view all the flashcards

Study Notes

Cell Membrane Structure

  • The cell membrane is composed of lipids and proteins, separating the cell's contents from the external environment.
  • It's a bilayer, consisting of two layers of phospholipids.
  • Phospholipid heads are hydrophilic (water-loving), positioning themselves towards the watery environment.
  • Phospholipid tails are hydrophobic (water-fearing), aligning away from the water.
  • The fluid mosaic model describes the cell membrane's structure, emphasizing fluidity and a mosaic pattern of embedded proteins.

Membrane Permeability

  • Cell membranes are semipermeable.
  • This means they control what substances pass through, selectively allowing specific molecules and substances to enter or exit.

Movement Across Membranes

  • Diffusion: The movement of liquid or gas molecules from a region of higher concentration to one of lower concentration across a membrane.
  • Osmosis: The diffusion of water across a semipermeable membrane. Water movement is influenced by solute concentration.
  • Hypertonic Solution: A solution with a higher solute concentration outside the cell than inside. Water exits the cell, leading to cell shrinkage or plasmolysis.
  • Hypotonic Solution: A solution with a lower solute concentration outside the cell compared to inside. Water enters the cell, potentially causing cell swelling or lysis.
  • Isotonic Solution: A solution maintains the same solute concentration inside and outside the cell; optimal for cell balance and health.

Facilitated Diffusion

  • Facilitated diffusion is a passive transport mechanism.
  • Carrier proteins aid in the movement of molecules across the membrane without energy input.
  • The shape of protein carriers changes during the passage of molecules.

Active Transport

  • Active transport requires energy (ATP).
  • Molecules move against the concentration gradient (from low to high concentration).
  • The sodium-potassium pump is an example of active transport and plays important roles in nerve impulse transmission and muscle contraction.

Bulk Transport

  • Bulk transport involves the movement of large molecules.
  • Exocytosis: Materials exit the cell, often through vesicle fusion with the membrane.
  • Endocytosis: Materials enter the cell, enclosing the substance in a vesicle that pinches off.
  • Receptor-mediated Endocytosis: Specific molecules are targeted for uptake by cell-surface receptors, concentrating and facilitating the entry of those molecules into the cell.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

Related Documents

Cell Membrane Notes PDF

Description

Explore the intricate structure and function of cell membranes through this quiz. Understand the composition, permeability, and the mechanisms of movement across membranes, including diffusion and osmosis. Test your knowledge on how these processes affect cellular behavior.

More Like This

Cell Membrane: Structure, Function, and Permeability
12 questions

Cell Membrane: Structure, Function, and Permeability

WellBalancedPeace avatar
WellBalancedPeace
Cell Membranes and Permeability
33 questions

Cell Membranes and Permeability

JollyPansy avatar
JollyPansy
Cell Membrane Structure and Function
20 questions

Cell Membrane Structure and Function

BenevolentKremlin avatar
BenevolentKremlin
Cytoplasmic Membrane Overview
21 questions

Cytoplasmic Membrane Overview

CharmingBoston8867 avatar
CharmingBoston8867
Use Quizgecko on...
Browser
Open
Browser
Browser