Plasma Membrane - Definition, Structure, Components, Functions Last Updated : 05 Sep, 2023 Summarize Comments Improve Suggest changes Share Like Article Like Report The plasma membrane acts as a protective barrier made of a lipid bilayer with embedded proteins that separates the interior of the cell from its external environment. The plasma membrane, also known as the cell membrane, is a vital component of the living organism that regulates the movement of substances into and out of the cell. It also participates in cell signaling and adhesion and contributes to the overall functionality and integrity of the cell which maintains a stable internal environment. Table of ContentWhat is a Plasma Membrane?Structure of the Plasma MembraneDiagram of Plamsa MembraneFunctions of Plasma MembraneFAQs on Plasma MembraneWhat is a Plasma Membrane?The plasma membrane, also referred to as the cell's outermost envelopes or structure, encircles both the cell and its organelles. This double-membrane cell organelle, also known as the phospholipid bilayer, is found in both prokaryotic and eukaryotic cells. The plasma membrane plays a pivotal role in endocytosis and exocytosis processes. It protects the cell from the external environment, governs interactions with surroundings, and supports essential cellular functions. Structure of the Plasma MembraneThe plasma membrane consists of a lipid bilayer, with two layers of lipids forming its foundation. Embedded within this lipid matrix are various proteins that contribute to its functionality. Among these proteins, receptor proteins enable cell communication, while adhesion proteins promote cellular cohesion. Serving as a protective barrier, the membrane regulates the passage of particles, displaying selective permeability that allows small particles to diffuse freely, and larger ones require specific transport channels. In 1972 fluid mosaic model was given by S.J. Singer and G.L. Nicolson. It described the complex structure of the plasma membrane with proteins embedded in a fluid lipid bilayer. Diagram of Plasma MembraneThe labeled diagram of plans membrane is shown below: Functions of Plasma MembraneThe plasma membrane acts as a physical barrier between the cytoplasm and extracellular space and allows biochemical reactions necessary for life to occur. The functions of plasma membrane are as follows: Barrier: Separates cell contents from the external environment.Selective Permeability: Regulates the entry and exit of substances.Cell Communication: Contains receptor proteins for signal detection.Cell Cohesion: Adhesion proteins help cells stick together.Endocytosis & Exocytosis: Facilitates material transport in and out of the cell.Homeostasis: Maintains internal balance by controlling molecule movement.Environment Interaction: Governs interactions with surrounding cells and molecules.Recognition: Displays unique patterns for cell identification.Flexibility: Allows cells to change shape and respond to the environment.Supports Essential Functions: Essential for cell survival, growth, and reproduction Comment More infoAdvertise with us Next Article Cell Wall B bhumikap7fmc Follow Improve Article Tags : School Learning Class 9 Biology Similar Reads CBSE Class 9 Science Notes 2023-2024 CBSE Class 9 Science Notes for the academic year 2023-2024 serve as a crucial foundation for students' further education. To excel in exams, it is critical to fully comprehend each topic while also thoroughly revising the subject matter. As Class 9 is a crucial period for students, GeeksforGeeks pro 15+ min read Chapter 1 - Matter in Our SurroundingsMatter is Made of Tiny ParticlesIn our surroundings, we come across different shapes, sizes, heights, structures, and textures. According to scientists everything in this universe is made up of a material called Matter. We can see that matter occupies some space and mass, in another way we can say that matter has some ‘volume’ and 8 min read States of Matter: Solid, Liquid, Gas and PlasmaMatter is made up of tiny particles. These particles are such small that we cannot see them by the naked eye. What ever we see in nature is made up of matter. Different matter exist in different form. These forms are called states of matter. States of MatterState of Matter or Phases of Matter is def 9 min read Change of State of MatterWhen cubes of ice melt into water or liquid boils into vapor, you may have seen changes in states of matter, but have you ever wondered why the substances change their form? When matter loses or gains energy, it changes its condition. When a substance gains energy, its molecules or atoms move faster 6 min read EvaporationEvaporation occurs when a liquid turns into a gas. Have you ever noticed that when a glass is left on the counter, the water begins to evaporate? It's evaporation, not thirsty fairies dwelling in your kitchen. Evaporation is the process by which molecules undergo a spontaneous transition from the li 10 min read Chapter 2 - Is Matter Around Us PureMixturesA mixture is a compound that is made up of two more chemical compounds or substances that do not combine together chemically. It is the physical combination of two or more substances that can retain their individual identities while they are mixed to form solutions, suspensions, or colloids. In this 6 min read Solution: Properties of SolutionA solution is a homogeneous mixture of two or more substances. A solution is formed of two components: the solute and the solvent. The substance dissolved in the solution is called the solute, whereas the component in which the solute is dissolved is known as a solvent. In this article, we will lear 10 min read Pure SubstancePure Substances in Chemistry are those which consist of only one type of atom or in the case of more than one type of atom they are always combined in a fixed ratio. What we consider as Pure is not a Pure Substance as per the definitions of chemistry. For Example, we consider milk as pure when it ha 15 min read Chapter 3 - Atoms and MoleculesLaws of Chemical CombinationLaws of Chemical Combination are one of the most fundamental building blocks of the subject of chemistry. As in our surrounding different matter reacts with each other and form various kind of different substances. Laws of Chemical Combination are the collection of laws that explains how these subst 7 min read What is Atom?Atoms are tiny particles that comprise all the things in the known universe. Atoms of an element are responsible for all chemical reactions occurring in nature. We know that atoms are made up of three fundamental particles namely, ElectronsProtonsNeutronsThese particles are also called subatomic par 8 min read Difference Between Atom And MoleculeAtoms and Molecules are the basic building blocks of all matter around us. There are some fundamental differences between atoms and molecules but they are essential in understanding the behavior of the world around us. Initially, atoms were thought to be indestructible, i.e. we can not further break 6 min read Chemical FormulaChemical formula is a way to describe chemical ratios of atoms that make up a specific chemical compound or molecule in chemistry. Chemical element symbols, numbers, and sometimes other symbols, such as parentheses, dashes, brackets, commas, plus (+), and minus (-) signs, are used to represent the c 6 min read Molecular MassMolecular Mass is the mass of all the atoms present in a molecule. In ancient India and Greece, philosophers have first given the idea of atoms and deeply studied them. Around 500 BC.Everything around is made up of very small units these units are atoms in the language of science, very small in the 8 min read Chapter 4 - Structure of the AtomCharged Particles in MatterCan we deduce from these actions that rubbing two items together causes them to become electrically charged? The presence of charged particles in an atom was discovered thanks to the efforts of many scientists. By 1900, it was established that the atom was an indivisible particle that contained at l 8 min read Atomic StructureAtomic structure is the structure of an atom that consists of a nucleus at the center containing neutrons and protons, while electrons revolve around the nucleus. Atoms are made up of a very tiny, positively charged nucleus that is surrounded by a cloud of negatively charged electrons. The earliest 15+ min read Arrangement of Electrons in the AtomsThe electron configuration of an element describes how electrons are distributed in their atomic orbitals. They follow a standard notation in which all electron-containing atomic subshells are placed in a sequence. This method was suggested by Bohr and Bury. The following rules are followed for writ 6 min read ValencyValency of an element is a measure of an atom's ability to combine with other atoms to create molecules or chemical compounds. The characteristics of an element that indicate how many more atoms can join one of its atoms in a covalent bond are known as valence, or valency, in chemistry. The term, wh 9 min read Relation Between Mass Number and Atomic NumberAtoms are the fundamental building blocks of matter, and they may combine in a variety of ways to produce various substances. You must be aware that all atoms are made up of electrons, protons, and neutrons. But did you know that the presence of these subatomic particles may explain an element's pro 8 min read IsotopesIsotopes are those atoms that are having the same atomic number or the same position in the modern periodic table but with different atomic masses. This difference in atomic mass arises from the different numbers of neutrons present in the nucleus of the atom. As they lie in the same position on the 8 min read Chapter 5 - The Fundamental Unit of LifeWhat are Living Organisms Made Up of?Robert Hooke discovered the cells in the year 1665. He was examining a thin slice of a cork, he saw that the cork resembled the structure of a honeycomb with too many little compartments. Then with the microscope, he observed these compartments and called them cells, meaning "little room" in Latin. 7 min read Plasma Membrane - Definition, Structure, Components, FunctionsThe plasma membrane acts as a protective barrier made of a lipid bilayer with embedded proteins that separates the interior of the cell from its external environment. The plasma membrane, also known as the cell membrane, is a vital component of the living organism that regulates the movement of subs 4 min read Cell WallCell wall is the non-living material that protects a cell's outermost layer. It might be firm, elastic, or periodically rigid. It serves as a filtration system as well as structural support and protection for the cell. Cell walls are absent in many eukaryotes, including animals, but they are present 7 min read Nucleus: Structure and FunctionThe nucleus (plural: nuclei) is a double-membraned organelle that is found only in eukaryotic cells. The name nucleus comes from a Latin term that means "nut kernel." The nucleus was discovered by Robert Brown in 1831. It is the first cell organelle that was discovered. The nucleus is responsible fo 7 min read Cytoplasm - Structure and FunctionCytoplasm is a semi-fluid, gel-like substance found in all living cells, both prokaryotic and eukaryotic. It surrounds the cell's organelles and nucleus. It acts as the medium in which various cellular processes like protein synthesis, metabolism, and many chemical reactions take place. The cytoplas 6 min read Endoplasmic Reticulum - Structure, Types And FunctionsEndoplasmic reticulum is an important cell organelle present in the cytoplasm of eukaryotic cells. The structure of the Endoplasmic reticulum comprises membranous tubules that are interconnected and carry out major cellular functions like protein synthesis, breakdown of carbohydrates, lipid synthesi 7 min read Golgi ApparatusGolgi apparatus is an organelle found in most of the eukaryotes. It consists of a series of flattened membrane sacs called cisternae. These cisternae are present one over the other to form the Golgi complex. It is responsible for packaging proteins into vesicles before secretion and therefore plays 4 min read Lysosomes - Definition, Types, Significance, FunctionsLysosomes are cell organelles that are also known as "suicide bags" or "cell recycling centers" of the cell. Lysosomes function in cellular waste disposal and programmed cell death (apoptosis). Lysosomes are eukaryotic membrane-bound cell organelles that appear small and spherical. Lysosomes arise f 8 min read MitochondriaMitochondria is a double membrane organelle present in the cytoplasm of all eukaryotic cells. Mitochondria generates energy in the form of ATP because of which mitochondria is known as the "powerhouse of the cell". In 1857 Albert von Kolliker first discovered the organelle and Carl Benda in 1898 gav 7 min read What are Plastids? - Class 9 BiologyThe body of all living organisms is made up of cells. Based on the cellular organization, some organisms are made up of single cells which are unicellular, and more than one cell which is multicellular organisms. Single-cell is able to perform all the life processes like gaining food, respiration, e 8 min read VacuolesVacuole is a cellular organelle that is found in plants, fungi, and some types of protists. In plant cells, it helps in maintaining turgor pressure, contributing to the plant's structural support and rigidity. Vacuoles contain various substances like ions, water, and waste products. It also contribu 5 min read Cell Division: Mitosis & Meiosis, Different Phases of Cell CycleCell division is the process by which a parent cell divides into two daughter cells. It occurs through two distinct processes, mitosis, and meiosis, each having its role in the life cycles of organisms. Mitosis is the division of a cell that produces two identical daughter cells, essential for growt 9 min read Chapter 6 - TissuesMeristematic Tissues - Definition, Features, Types, RoleMeristematic tissues are a type of plant tissue that plays an important role in the growth and development of plants. These tissues consist of undifferentiated cells that can divide and differentiate into various types of specialized cells. Meristematic tissues are mainly found in that part of the p 6 min read Structure and Types of Animal TissuesAnimal tissue is a group of cells along with intercellular substances that perform one or more functions in the body. The structure of animal tissues depends on their function and location in the body. There are four types of animal tissues; epithelial, connective, muscle, and nervous tissue which w 6 min read Permanent Tissues - Diagram, Types Notes Biology Class 9Permanent tissues are a type of plant tissue that has completed its growth and differentiation. They remain in a specialized state throughout the plant's life. These tissues perform specific functions and are responsible for the overall structural growth and function of the plant. There are three ma 7 min read Epithelial Tissue - Introduction, Characteristics, Types, ImportanceEpithelial tissue is what makes up this part of the animal's anatomy, and it may be found on both the outside and the inside of the body. The body structure of multicellular organisms is more complicated than that of unicellular organisms, in which every important cellular function, such as nutritio 13 min read Overview and Types of Connective TissueAs their name suggests, connective tissues serve to both support and link the many organs and tissues found throughout the body. They are located in vast quantities all throughout the body, Their genesis may be traced back to the mesoderm(embryo). A few cells that are located in the interfacial netw 13 min read Muscular TissueMuscular tissue is a type of tissue present in animals that is specialized for contraction and movement. Muscular tissue is one of the four main types of tissues, the others being epithelial, connective, and nervous tissue. Muscular tissue is made up of muscle fibers. There are three types of muscul 5 min read Nervous Tissue - Definition, Characteristics, Functions, TypesNervous tissue is one of the four types of animal tissue, along with epithelial tissue, connective tissue, and muscle tissue. Nervous tissue is composed of two main types of cells: neurons and glial cells. Nervous tissue is present in the brain, spinal cord, and nerves all around the body. Nervous t 6 min read Chapter 7 - MotionWhat is Motion?Motion is defined as the change in the position of an object with respect to time i.e. when an object changes its position according to time it is said to be in the state of motion. Everything in the universe is in a state of continuous motion, for example, the moon revolves around the planets, the 12 min read Measuring the Rate of MotionWe use general things around us that are moving, like if we see around us, monitor air moving around us, like we have clocks with the hands moving, we all know that day and night is caused because of motion of Earth around the Sun, yet seasons are caused because of it. So we are going to study in de 10 min read AccelerationAcceleration is defined as the rate of change in velocity. This implies that if an object’s velocity is increasing or decreasing, then the object is accelerating. Acceleration has both magnitude and direction, therefore it is a Vector quantity. According to Newton's Second Law of Motion, acceleratio 9 min read Equation of Motion by Graphical MethodA famous British scientist Isaac Newton derived three equations of motion that describe the most fundamental concepts of motion of an object. These equations govern the motion of an object in one, two, and three dimensions. These equations are easily used to calculate the values or the expressions f 12 min read Uniform Circular MotionUniform Circular Motion as the name suggests, is the motion of a moving object with constant speed in a circular path. As we know, motion in a plane only has two coordinates, either x, and y, y and z, or z and x. Except for Projectile motion, circular motion is also an example of motion in a 2-D pla 9 min read Chapter 8 - Force and Laws of MotionBalanced and Unbalanced ForcesForces are required to move, turn, shift, release, shut, drive, drag, and so on. When you throw a ball, you are exerting energy on it to propel it through the air. A push or pull is referred to as a force. Forces can cause objects to move, and they can also slow, stop, or change the direction in whi 8 min read Newton's First Law of MotionBefore the revolutionary ideas of Galileo and Newton, people commonly believed that objects naturally slowed down over time because it was their inherent nature. This assumption stemmed from everyday observations, where things like friction, air resistance, and gravity seemed to slow moving objects. 15+ min read Mass and InertiaMany events are seen in the field of physics, yet some of them have eluded explanation for a long time. Newton proposed three rules of motion, which became known as Newton's Laws of Motion. These laws were a novel finding in the physical universe, and they were frequently employed to explain situati 8 min read Newton's Second Law of Motion: Definition, Formula, Derivation, and ApplicationsNewton's Second Law of Motion is a fundamental principle that explains how the velocity of an object changes when it is subjected to an external force. This law is important in understanding the relationship between an object's mass, the force applied to it, and its acceleration.Here, we will learn 15 min read Newton's Third Law of MotionWhen you jump, you feel the gravitational force pulling you down towards the Earth. But did you know that at the same time, you are exerting an equal force on the Earth? This phenomenon is explained by Newton's Third Law of Motion. Newton's Third Law of MotionNewton's Third Law of Motion is a founda 13 min read Chapter 9 - GravitationGravitational ForceHave you ever wondered why the Earth revolves around the Sun and not the other way around? Or why does the Moon remain in orbit instead of crashing into Earth? If the Earth pulls the Moon and the Moon pulls the Earth, shouldn’t they just come together? What keeps them apart?All these questions can b 11 min read Free FallThere are always two cases of things falling to the ground. One example is when something is thrown to the ground, such as throwing a ball. At the same time, the other case is when something is dropped to the ground. For example, dropping the ball or accidentally dropping the phone from your hands ( 6 min read Mass and WeightMass and Weight are commonly used in the same manner by the general masses but there are differences between both Mass and Weight, where Mass is the measure of Inertia unlike Weight which is a measure of force acting on a body towards the heavy body. But yet still many people use these two terms int 10 min read What is Pressure?Have you ever thought about why a needle is so thin, why fence spikes are pointed, or why a hammer's head is flat? It’s all about pressure. Pressure is the force applied to a specific area. A needle’s sharp tip concentrates the force, allowing it to easily pierce fabric. If it were blunt, the force 7 min read Archimedes PrincipleArchimedes Principle is a fundamental concept in fluid mechanics, credited to the ancient Greek mathematician and physicist Archimedes. According to Archimedes' Principle, when an object is immersed in a fluid the object experiences an upward force whose magnitude is equal to the weight of the fluid 12 min read Like