Biology Chapter: Plasma Membrane

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Questions and Answers

What does the plasma membrane do?

Produces energy for the cell

Protects a cell from its environment (correct)

Stores genetic information

Helps in protein synthesis

The plasma membrane is selectively permeable.

True

What is the composition of the phospholipid bilayer?

Phospholipid molecules with polar heads facing outwards and nonpolar tails facing inwards.

What is the role of transport proteins in the plasma membrane?

They move substances or wastes through the plasma membrane. Signup and view all the answers

What does amphipathic mean?

Having a hydrophobic tail and a hydrophilic head. Signup and view all the answers

What is a bilayer?

A membrane with two fluid layers. Signup and view all the answers

How does a cell's plasma membrane function?

Selective permeability. Signup and view all the answers

What are the roles of proteins in the plasma membrane?

They anchor the membrane and create tunnels for substances to enter and exit. Signup and view all the answers

What are the roles of carbohydrates in the plasma membrane?

They define the cell's characteristics and help in identifying chemical signals. Signup and view all the answers

What role does cholesterol play in the plasma membrane?

Helps to prevent fatty-acid tails from sticking together, contributing to membrane fluidity. Signup and view all the answers

What repels water and is positioned among the phospholipids?

Nonpolar cholesterol. Signup and view all the answers

What is attracted to water?

Polar head. Signup and view all the answers

How many tails does each phospholipid have?

2 Signup and view all the answers

What does a phospholipid bilayer look like?

Sandwich. Signup and view all the answers

What model describes the plasma membrane?

Fluid mosaic model. Signup and view all the answers

How many layers does the plasma membrane consist of?

2 Signup and view all the answers

What are the two components that help the function of the plasma membrane?

Cholesterol and transport proteins. Signup and view all the answers

Identify the molecules in the plasma membrane that provide basic structure and fluidity.

Transport proteins, cholesterol, and carbohydrates. Signup and view all the answers

Study Notes

Plasma Membrane Overview

The plasma membrane serves as a protective barrier for the cell, regulating interaction with its environment.
Composed of a phospholipid bilayer, it allows the passage of nutrients into the cell while facilitating waste removal.

Key Characteristics

Selectively Permeable: The membrane allows certain substances to cross while blocking others, maintaining internal balance.
Phospholipid Bilayer: Features two layers of phospholipid molecules, with hydrophilic heads facing outward and hydrophobic tails directed inward.

Membrane Proteins

Transport Proteins: Facilitate movement of substances and waste across the membrane.
Structural Proteins: Anchor the membrane to the cell's internal framework, maintaining its shape.
Receptor Proteins: Located on the outer surface; they transmit signals and facilitate communication with the environment.

Role of Carbohydrates

Carbohydrates attached to proteins help define cell identity and respond to chemical signals, enabling cellular communication.

Cholesterol Functions

Maintains membrane fluidity by preventing the fatty-acid tails of phospholipids from adhering to one another.
A balanced cholesterol intake is important for optimal cell function.

Phospholipid Structure

Each phospholipid molecule consists of two tails.
The polar head is hydrophilic (water-attracting), while the nonpolar tail is hydrophobic (water-repelling).

Membrane Fluidity

The Fluid Mosaic Model describes the dynamic nature of the plasma membrane, with various components, including proteins and cholesterol, constantly in motion.

Key Membrane Components

Transport Proteins: Essential for the transport of substances.
Cholesterol: Contributes to membrane stability and fluidity.
Carbohydrates: Play a critical role in cell recognition and signaling.

Visualization of the Membrane

The phospholipid bilayer resembles a sandwich, with polar heads facing the exterior and tails clustered inward, ensuring structural integrity and functionality.

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Description

Test your knowledge on the plasma membrane with these flashcards. Learn key terms such as selectively permeable and understand the essential functions that the plasma membrane performs for the cell. Perfect for biology students wanting to reinforce their understanding of cell structure.