Biology Chapter 3 Flashcards

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Why are cell membranes semi-permeable?

Cell membranes are semi-permeable, which means molecules can move through them. This is important for cells to survive. Osmosis is where solvent molecules (usually water) move from one side of a cell membrane to the other.

Why are cell membranes selectively permeable?

It only lets certain things in and out. The structure of the phospholipid bilayer prevents random things from drifting through, and proteins act like doors, letting the right substances in and out.

What types of particles do not diffuse through membranes well?

Many large molecules, such as glucose and other sugars, cannot cross the membrane.

What does hypotonic mean?

Having a lower concentration of solute than another solution. Signup and view all the answers

What does isotonic mean?

When the concentration of two solutions is the same. Signup and view all the answers

What does hypertonic mean?

When comparing two solutions, the solution with the greater concentration of solutes. Signup and view all the answers

What is active transport?

Energy-requiring process that moves material across a cell membrane against a concentration difference. Signup and view all the answers

What is passive transport?

The movement of substances across a cell membrane without the use of energy by the cell. Signup and view all the answers

What is facilitated transport?

A process by which material moves down a concentration gradient (from high to low concentration) using integral membrane proteins. Signup and view all the answers

What are the processes of endocytosis?

The process of capturing a substance or particle from outside the cell by engulfing it with the cell membrane and bringing it into the cell. Signup and view all the answers

What is the process of exocytosis?

When particles are too big to exit through protein channels, the membrane surrounding the material fuses with the cell membrane and changes shape. Signup and view all the answers

Describe the structure of the plasma (cell) membrane.

Phospholipid bilayer arranged back-to-back. Signup and view all the answers

What is osmosis?

Diffusion of water through a selectively permeable membrane. Signup and view all the answers

What does hypertonic mean in relation to a solution?

High solute, low water. Signup and view all the answers

What does hypotonic mean in relation to a solution?

Low solute, high water. Signup and view all the answers

Study Notes

Cell Membrane Characteristics

Cell membranes are semipermeable, allowing selective movement of molecules essential for cell survival.
Osmosis involves the movement of solvent molecules, primarily water, across a cell membrane.

Selective Permeability

Cell membranes only permit specific substances to enter or exit.
The phospholipid bilayer structure restricts indiscriminate passage, while membrane proteins function as selective channels.

Particle Diffusion

Certain small molecules, like hydrocarbons and oxygen, can easily diffuse through the membrane.
Larger molecules, including glucose and other sugars, are restricted from passing through directly.

Solution Concentration Terms

Hypotonic: A solution with a lower concentration of solute compared to another solution.
Isotonic: Two solutions with equal concentrations of solute.
Hypertonic: A solution with a higher concentration of solute compared to another solution.

Transport Mechanisms

Active Transport: Requires energy to move materials against a concentration gradient through the membrane.
Passive Transport: Occurs spontaneously without energy input, allowing substances to move across the membrane.
Facilitated Transport: Utilizes integral membrane proteins for the movement of materials down a concentration gradient from high to low concentration.

Endocytosis and Exocytosis

Endocytosis: Engulfing substances or particles from outside the cell to bring them inside via the cell membrane.
Exocytosis: A process for particles that are too large to pass through protein channels, where the cellular membrane surrounds and releases materials by fusing with the membrane.

Plasma Membrane Structure

Composed of a phospholipid bilayer arranged back-to-back, providing a dynamic and flexible barrier.

Osmosis and Water Movement

Osmosis: The diffusion process specifically referring to the movement of water through a selectively permeable membrane.
Hypertonic: Describes a condition with high solute concentration and low water potential.
Hypotonic: Refers to a situation with low solute concentration and high water potential.

Studying That Suits You

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

Description

This quiz covers key concepts related to cell membranes, focusing on their semi-permeable and selectively permeable nature. Understanding these properties is crucial for grasping how cells interact with their environment and maintain homeostasis. Review these flashcards to enhance your knowledge of cellular biology.