Cell Membrane Structure in Animal Cells: Complete Guide! - (2023)

This publication provides detailed information on the structure of the cell membrane in animal cells.

Cell membranes, or biological membranes, are thin, quasified, flexible, film-like structures found both extracellularly and around the protoplast of an animal cell.

The following are terms related to animal cell membranes, which will be discussed briefly.

  • membrane appearance
  • membrane composition
  • fluid mosaic template
  • cell membrane functions
  • passive transport
  • Active transport
  • Cotransporte
  • Massive transport
  • pinocytosis and phagocytosis
  • membrane transport
  • Sodium-potassium exchange pump

membrane appearance

The membrane is approximately 7.5 nm thick. Due to this size, they are not visible under a light microscope. However, its presence was inferred long before its observation due to plasmolysis, the burstinganimal cellsplaced in hypotonic solution.

Cell membranes are visible under an electron microscope. The membrane appears under the microscope.trilaminarThree-layer medium. There is an intermediate electron shell that is transparent and is covered by two electron dense shells on either side of the transparent shell. It contains a number of particles of different sizes.

membrane composition

The membrane is made up of three types of components: proteins, carbohydrates and lipids. Lipids are generally phospholipids or phosphoglycerides.this consists ofhydrophilic pole headand nonpolar hydrophobic tail. Since there are hydrophobic and hydrophilic ones, they are calledamphipathicPhospholipids form a bilayer when in contact with water. Other lipids present in the membrane are sphingolipids, cerebrosides, gangliosides, and cholesterol. Cholesterol gives stability and rigidity to animal cells.

The membrane has a series of proteins that work like an enzyme. For example, ATP-ase helps with ATP synthesis and breakdown, Cyt P-450 helps with hydroxylation.receptor proteinThey act as neurotransmitters to receive information.

The carbohydrates present in the membrane are oligosaccharides. The latter can be branched or unbranched. Glycolipids and glycoproteins are associated with the outer surfaces of proteins and lipids.

fluid mosaic template

It is the most widely accepted model of the cell membrane given by Singer and Nicolson in 1972. According to the fluid mosaic model, cell membranes have almost similar consistency. The lipid bilayer is continuous and contains other lipids. For example, B. cholesterol is present in animal membranes.Proteins appear as a mosaic both within the lipid bilayer and on both surfaces. They are known asprotein drumsticksin a sea of ​​lipids.

Proteins often tend to change position. Extrinsic and intrinsic are the two categories of membrane proteins.

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intrinsic proteins

It occurs within the lipid bilayer and reaches its various depths. transmembraneProteins are embedded in the membrane.of intrinsic proteins that form a channel to admit water, ions, and some small solutes.Some of the channels have gate mechanisms to allow access to certain substances. Intrinsic proteins develop hydrophobic interactions with phospholipid molecules. Because of this, intrinsic proteins cannot be easily separated from the membrane without destroying it.

extrinsic proteins

It is also known as a peripheral protein that is found on both sides of the membrane. These proteins are available in greater abundance on the inner surface of the membrane than on the outer side of the membrane.They are also attached to the polar heads of intrinsic proteins through weak electrostatic bonds and ionic bonds. Therefore, peripheral proteins are easily displaced by sonication, mild detergents, and chelated hypotonic solutions.

cell membrane functions

  • keep cell content: Contains semi-liquid protoplasmic content.
  • Schutz: helps protect the cell from injury.
  • organelles: Also covers various organellesKern, mitochondria, Golgi apparatus, endoplasmic reticulum, etc.
  • compartmentalization: Separates cells from the external environment and cell organelles from the cytosol.
  • Cell recognition: use of glycolipids and glycoproteins, cell membranesit can also distinguish between similar and dissimilar cells.
  • Antigen: Antigens on cell membranes help determine blood type, immune response, and acceptance or rejection of transplantation.
  • cell connectionsThey help hold animal cells together.
  • Microvilosidades:They have nubs that help increase absorption.
  • endocytosis: The membrane develops membrane vesicles to absorb materials in large quantities.
  • Exocytosis:The membrane aids in the removal of waste.
  • directed patency: Allows you to enter only the selected substances.
  • Remaining:Diaphragms do not leak. They do not allow absorbed substances to escape to the outside.
  • electron transport: Electron transport chainsOccurs in the mitochondrial membrane.
  • Osmosis: The membrane contains special water channels through which osmosis occurs.
  • transport proteins: AidActive transportand is found in membranes.
  • Membranes:A variety of enzymes are attached to the membrane to carry out various biochemical activities, such as hydrolysis and ATP synthesis.
  • membrane receptors:It contains various receptors for hormones, neurotransmitters, immunoglobulins, and various other biochemicals.

membrane transport

It is the passage of biochemicals, metabolites, and by-products through biological membranes.. There are four types:passive transport, active transport, symport-antiport transport and bulk transport.

passive transport

It is the movement of substances from one part or area of ​​a system to another without the system having to expend energy, eg. B. from the outside incell through the cell membrane.

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Passive transport is more common along the concentration gradient and electrochemical potential. Examples:Diffusionand osmosis. The cell membrane has narrow channels produced by tunneling proteins. There are two types, aquaporins and ion channels. Aquaporins allow the passage of water according to osmotic forces. A specific ion channel allows ions to cross the membrane. CO2y-oh2It is believed that they are passed along with the water.

Active transport

It is the mode of transport across the cell membrane that consumes metabolic energy. Energy is derived primarily from ATP.

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Active transport is the most common method of ion uptake in animal cells. this is approximately2+, k+, of+,Fe2+, urate, many sugars and amino acids. Active transport normally occurs against the concentration gradient. It is unidirectional and highly selective.


Cotransport allows the membrane to move substances and other materials in symport (same direction) or antiport (opposite direction). This is sometimes called facilitated diffusion.For cotransport, the transport proteins have additional binding sites. For example, glucose, nucleosides, and some groups of amino acids go with Na+.

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Massive transport

It is the means of transporting large amounts of materials, micromolecules, macromolecules and food particles through the membrane.Mass transport involves chemical stimulation, folding, and fusion of the membrane to produce vesicles called transport vesicles. Transportation takes place both inward and outward.

endocytosis youExocytosis is of two types.of mass transportation.


Allows cells to internalize extracellular materials via transport vesicles,Endososomo.Endocytosis is furthermore of two types,in pinositasmiphagozytosa.


With the help of transport bubbles, the so-called exocytic vesicles, it transports substances from the inside of the cell to the outside. The secretory or excretory products are packaged in vesicles by the Golgi bodies.

frequent questions

Q1. Difference between pinocytosis and phagocytosis..

Pinocytosis is the uptake of extracellular fluid, ions, and molecules by small vesicles, or pinosomes, formed by the folding of the cell membrane.. Lysosomes can participate in the digestion of extracellular substances.

Phagocytosis is the cellular ingestion of large particles such as microbes, cell debris, degenerating cells, etc. Pseudopod-like bulges are formed to enclose the solid materials.Lysosomes are essential for the breakdown and digestion of solid foods. Undigested substances are excreted throughEfagiao exocytosis

Q2. Describe the mechanism of active transport..

Active transport is mediated by transporters or transport proteins. They are whole protein particles.cell membraneThey have an affinity for certain solute particles.A transporter associates with the solute at the surface and formsdissolved transporter complex.The complex gains energy from ATP and undergoes a conformational change. In the complexed state, the carrier particle transports the solute to the other side of the membrane, where it is released. The carrier is released and returns to its original state to combine with another solute.

Q3 Give a brief description of the sodium-potassium exchange pump.

It works on most cells in the body. A large α subunit and a small β subunit make up the transport proteins. The interior of the larger subunit has three receptor sites for Na+ions and a site for ATPase activity.The outer part of this subunit has two receptor sites for K+ions The carrier binds three Na+Ions from inside the cell and two K+Extracellular fluid ions. With the help of the energy obtained from ATP, the transporter undergoes a conformation change, releases three Na+ions in the extracellular fluid and two K+ions inside the cell.

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The Na+-K+ exchange pump helps maintain a higher concentration of Na+ ions in the extracellular fluid than in the intracellular content. Compared to the extracellular fluid, the intracellular K+ concentration is higher. The Na+-K+ exchange pump is responsible for the resting potential of nerve cells. it is also encouragingactive secondary transport.


To close this post, let's close this animalThe cell membrane is thin in structure.but it separates the components of the cell from the external environment. It also allows for the transfer of various membrane substances, making the membrane inherently semi-permeable due to the presence of various proteins and lipids.


What is the structure of the cell membrane in an animal cell? ›

The fundamental structure of the membrane is the phospholipid bilayer, which forms a stable barrier between two aqueous compartments. In the case of the plasma membrane, these compartments are the inside and the outside of the cell.

What are the 3 main molecules of an animal cell membrane? ›

There are three major classes of membrane lipid molecules—phospholipids, cholesterol, and glycolipids. The lipid compositions of the inner and outer monolayers are different, reflecting the different functions of the two faces of a cell membrane.

Can you remember all the structural components of a cell membrane and be able to list them down? ›

These components are phospholipids, proteins, carbohydrates and cholesterol or sterols.

Which of the following are structural components of the cell membrane choose 3 answers? ›

The principal components of the plasma membrane are lipids ( phospholipids and cholesterol), proteins, and carbohydrates. The plasma membrane protects intracellular components from the extracellular environment.

What is the function of animal cell membrane? ›

The cell membrane, therefore, has two functions: first, to be a barrier keeping the constituents of the cell in and unwanted substances out and, second, to be a gate allowing transport into the cell of essential nutrients and movement from the cell of waste products.

What is the function of cell membrane in animal cell? ›

The cell membrane regulates the passage of substances into and out of cells by being selectively permeable to ions and organic molecules. The cell membrane's primary role is to shield the cell from its environment. The plasma membrane is another name for the cell membrane. It is the outside layer of animal cells.

What are the 2 main types of membrane structure? ›


Membrane structure for pervaporation can be divided into two major classes, dense or asymmetric membranes. In industrial applications, asymmetric membranes have been applied because of their higher flux compared to the dense membranes.

What are the 3 parts of the cell membrane structure? ›

  • Lipids (phospholipids and cholesterol)
  • Proteins.
  • Carbohydrates.

What are 3 functions of the cell membrane? ›

Biological membranes have three primary functions: (1) they keep toxic substances out of the cell; (2) they contain receptors and channels that allow specific molecules, such as ions, nutrients, wastes, and metabolic products, that mediate cellular and extracellular activities to pass between organelles and between the ...

How do you remember the cell membrane easily? ›

  1. The cell membrane controls what goes in and out of the cell.
  2. The cell membrane is like a screen door, because a screen door holds things out but lets air in.

What are the 4 major components of the cell membrane and how are they organized? ›

Answer and Explanation: The four parts of the cell membrane are phospholipids, proteins, carbohydrates and cholesterol. The main component of the plasma membrane are phospholipids. They are arranged in a bilayer that helps keep large, hydrophobic molecules out of the cell.

What are the major structural components of a cell membrane ____? ›

The principal components of the plasma membrane are lipids (phospholipids and cholesterol), proteins, and carbohydrate groups that are attached to some of the lipids and proteins.

What is the structure of the cell membrane and its function? ›

The cell membrane, also called the plasma membrane, is found in all cells and separates the interior of the cell from the outside environment. The cell membrane consists of a lipid bilayer that is semipermeable. The cell membrane regulates the transport of materials entering and exiting the cell.

What are the 5 parts of the cell membrane? ›

The principal components of a plasma membrane are lipids (phospholipids and cholesterol), proteins, and carbohydrates attached to some of the lipids and some of the proteins. A phospholipid is a molecule consisting of glycerol, two fatty acids, and a phosphate-linked head group.

How many structures are in a cell membrane? ›

The cell membrane consists of a lipid bilayer, made up of two layers of phospholipids with cholesterols (a lipid component) interspersed between them, maintaining appropriate membrane fluidity at various temperatures.

What type of structure is a membrane? ›

membrane structure, Structure with a thin, flexible surface (membrane) that carries loads primarily through tensile stresses. There are two main types: tent structures and pneumatic structures. The Denver International Airport (1995) features a terminal building roofed by a white membrane stretched from steel masts.

What is membrane structure called? ›

In Summary: Structure of the Cell Membrane

The modern understanding of the plasma membrane is referred to as the fluid mosaic model. The plasma membrane is composed of a bilayer of phospholipids, with their hydrophobic, fatty acid tails in contact with each other.

What is cell membrane made of? ›

What Are Cellular Membranes Made Of? With few exceptions, cellular membranes — including plasma membranes and internal membranes — are made of glycerophospholipids, molecules composed of glycerol, a phosphate group, and two fatty acid chains.

What are the 7 functions of the cell membrane? ›

Metabolic Activities More about each of these functions of the cell membrane follows below:
  • Mechanical Structure. Defines/encloses the Cell. ...
  • Selective Permeability. ...
  • Active Transport. ...
  • Bulk Transport: Exocytosis & Endocytosis. ...
  • Markers & Signalling. ...
  • Metabolic Activities.

Which best describes the structure of a cell membrane? ›

The most widely accepted model for plasma membrane structure is the fluid - mosaic model. According to this model, the plasma membrane is made up of a phospholipid bilayer which has proteins embedded in it.

What type of cell is cell membrane? ›

The plasma membrane

Both prokaryotic and eukaryotic cells have a plasma membrane, a double layer of lipids that separates the cell interior from the outside environment. This double layer consists largely of specialized lipids called phospholipids.

What are the 4 major functions of the cell membrane? ›

The four main functions of the plasma membrane include identification, communication, regulation of solute exchange through the membrane, and isolation of the cytoplasm from the external environment.

What are the properties of cell membranes? ›

(1) Cell membranes are thin enclosures that form closed boundaries. (2) Cell membranes are made up of lipids, proteins and carbohydrates. (3) Cell membranes consists of a phospholipid bilayer. (4) Cell membranes are held together by non-covalent interactions (5) Membranes are fluid-like structure.

What grade do you learn cell structure? ›

9th Grade Biology Topics, Part A

Part A of our ninth grade biology topics covers the structure and function of cells. We learn to draw different types of cells, and we learn about what their parts do. The focus is on understanding human cells and what keeps the human body functioning in a state of health.

What is the acronym used to remember the cell stages in order? ›

Stages of mitosis: prophase, metaphase, anaphase, telophase. Cytokinesis typically overlaps with anaphase and/or telophase. You can remember the order of the phases with the famous mnemonic: [Please] Pee on the MAT.

What is the best way to study for Cell Biology? ›

Study Strategies for Biology
  1. Make learning a daily routine.
  2. Flesh out notes in 24-48 hour cycle. “ ...
  3. Study to understand, not just to memorize words.
  4. Learn individual concepts before integrating it together.
  5. Use active study methods.​
  6. You need to test yourself frequently to truly gauge how much you comprehend.

What is the process of cell membrane? ›

Pinocytosis is a process by which extracellular fluid is engulfed by invaginating cell membranes, forming a vesicle that then separates from the membrane. This vesicle may move through the cell cytoplasm and release its contents on the other side of the cell layer by means of exocytosis.

What are 3 ways materials move across the cell membrane? ›

Movement of Substances Across Cell Membrane
  • Simple diffusion.
  • Facilitated diffusion.
  • Osmosis.

Which membrane is easiest to pass? ›

Small nonpolar molecules, such as O2 and CO2, are soluble in the lipid bilayer and therefore can readily cross cell membranes. Small uncharged polar molecules, such as H2O, also can diffuse through membranes, but larger uncharged polar molecules, such as glucose, cannot.

What is the basic structure of a cell membrane quizlet? ›

Key Concept: What is the basic structure of a cell membrane? The core of nearly all cell membranes is a double-layered sheet called a lipid bilayer. Most cell membranes contain protein molecules that run through the lipid bilayer, and carbohydrate molecules are attached to these proteins.

What are the layers of the cell membrane? ›

The cell membrane is composed of two layers, the inner and outer phospholipid layers.

What is the structure of membrane? ›

Biological membranes consist of a double sheet (known as a bilayer) of lipid molecules. This structure is generally referred to as the phospholipid bilayer. In addition to the various types of lipids that occur in biological membranes, membrane proteins and sugars are also key components of the structure.

What is the structure and function of an animal cell? ›

The animal cell structure is composed of the cell membrane, cytoplasm, and cell organelles. The organelles are covered with a plasma membrane. The nucleus is the control center of the cell and contains the cell's genetic material or DNA. Mitochondria are organelles that help the cell break down food and release energy.

What is the structure of the cell membrane in a plant cell? ›

In bacterial and plant cells, a cell wall is attached to the plasma membrane on its outside surface. The plasma membrane consists of a lipid bilayer that is semipermeable. The plasma membrane regulates the transport of materials entering and exiting the cell.

How is the structure of the cell membrane important for its function? ›

It forms a physical barrier and as a barrier between the cell and the external environment as it allows only selected necessary molecules to pass through it and at the same time prevents entry of unwanted / unnecessary substances. It also regulates the entry and exit of molecules into and out of the cell.

Do animal cells have a cell membrane? ›

Animal cells simply have a cell membrane, but no cell wall.

Which of the following is a structure of animal cell? ›

Animal cells contain centrioles, cylindrical organelles that help in cell division and are absent in plant cells.

What is the main function of the cell structure? ›

They provide structure for the body, take in nutrients from food, convert those nutrients into energy, and carry out specialized functions. Cells also contain the body's hereditary material and can make copies of themselves.

What is the structure of the cell membrane quizlet? ›

The cell membrane is a complex phospholipid bilayer that envelops the cell. It separates the extracellular and intracellular environments. The structure of the cell membrane is described as a fluid-mosaic model. This comes from the fact that the proteins are scattered through the phospholipid bilayer.


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