Cell Membrane Function and Structure

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary function of the cell membrane?

To provide structure and support to the cell

To regulate the movement of substances in and out of the cell (correct)

To facilitate cell division

To store genetic material

Why is the cell membrane often referred to as the plasma membrane?

Because it is the outer limiting membrane of the cell (correct)

Because it is a barrier to all molecules

Because it has a plasma-like appearance under a microscope

Because it is composed entirely of lipids

Which statement accurately describes the visibility of the cell membrane using a light microscope?

It can be seen with special staining techniques

It is clearly visible due to its thickness

It is not visible because it is too thin (correct)

It appears as a single thick line

What alternative name is commonly used for the cell membrane?

Plasmalemma Signup and view all the answers

What characteristic of the cell membrane allows it to control cellular interactions?

Its selectively permeable properties Signup and view all the answers

What percentage of the content is made up of proteins?

60% Signup and view all the answers

Which type of membrane proteins are categorized as intrinsic proteins?

Integral membrane proteins Signup and view all the answers

What molecules primarily compose the lipid content?

Phospholipids and cholesterol Signup and view all the answers

Which of the following statements is true regarding the composition?

Lipid contents account for 30% of the overall composition. Signup and view all the answers

What percentage of the total composition is made up of lipids and proteins combined?

70% Signup and view all the answers

What is one primary function of the cell coat?

To provide protection to the cell. Signup and view all the answers

Which component is NOT part of the cell coat?

Water Signup and view all the answers

How does the cell coat aid in the exchange of materials?

By facilitating various methods of exchange. Signup and view all the answers

Which of the following best describes the role of proteins in the cell coat?

They influence cell shape and fluidity. Signup and view all the answers

What is a characteristic feature of the cell membrane's function related to material exchange?

It interacts selectively with different types of molecules. Signup and view all the answers

What process describes the movement of substances from inside a cell to the extracellular fluid?

Exocytosis Signup and view all the answers

Which of the following accurately describes exocytosis?

The expulsion of vesicle contents to the extracellular space Signup and view all the answers

What happens to the vesicle during exocytosis?

It fuses with the cell membrane and releases its contents Signup and view all the answers

Which type of substances are typically involved in the process of exocytosis?

Large molecules like proteins or hormones Signup and view all the answers

In which scenario would exocytosis most likely occur?

A cell expelling neurotransmitters into the synaptic cleft Signup and view all the answers

What is the thickness range of the layer mentioned?

8-10 nm Signup and view all the answers

What effect does PAS stain have on the cell structure?

Stains carbohydrates of the cell coat Signup and view all the answers

What distinguishes the trilaminar appearance of the layer?

An outer and inner dark layer with a light middle layer Signup and view all the answers

What microscopy method is typically insufficient for resolving details of this layer?

Light microscopy Signup and view all the answers

Under what conditions can the layer's details be observed with light microscopy?

If stained with a specific stain Signup and view all the answers

Study Notes

Cell membrane (plasmalemma or plasma membrane)

The outermost layer of the cell
Not visible under a light microscope (LM) due to its thinness (8-10 nm)
May be visible with oblique sections or when stained with PAS stain, which stains carbohydrates of the cell coat
Appears as a trilaminar structure under an electron microscope (EM) with an outer and inner dark layer separated by a middle light layer
Comprised of lipids (30%) and proteins (60%)
Lipid layer contains phospholipids and cholesterol
Proteins can be either intrinsic (integral) or extrinsic (peripheral)
It is covered by a cell coat, which consists of proteins and carbohydrates

Functions of the cell membrane

Protects the cell
Regulates the exchange of materials between the cell and its environment
Exocytosis is a process by which cellular contents are extruded into the extracellular fluid via membranous vesicles

Studying That Suits You

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

Description

This quiz explores the structure and functions of the cell membrane, also known as the plasmalemma or plasma membrane. Learn about its composition, visibility under different microscopes, and key roles in cellular regulation and protection.