Animal Cell 

Animal cell is a type of Eukaryotic Cell. Eukaryotic cells are the type of cell thta contains nucleus and other membrane-bound organelles. Animal cells are typically smaller and less complex than plant cells. They  are found in the body of all multicellular animals. Animal cells are typically round or irregular in shape. They  are surrounded by a plasma membrane that controls the movement of materials in and out of the cell. Inside the animal  cell there are several organelles that perform specific functions. The nucleus of an animal cell  contains  genetic material of the Cell. Mitochondria of Animal cells produce energy for the cell. Other Important organelles found in animal cells are endoplasmic reticulum, Golgi apparatus, lysosomes,  centrioles etc . Animal cells also contain cytoskeleton ,Cytoskeleton is a network of protein fibers that gives the cell shape and helps it move.  

Animal Cells do not have a Cell Wall. They have a cell membrane that surrounds the cell and helps to control the movement of materials in and out of the cell.

Animal Cell Structure

Animal cells are the basic structural and functional units of all Animals. They have complex structures and  are composed of various organelles and structures that perform specific functions.

Various Structures of Animal Cell are as follows- 

Cell membrane

• The Animal cell membrane is also  known as the plasma membrane. 
• It is a thin layer of lipids and proteins that surrounds and encloses the Contents of an Animal cell. 
• Cell Membrane  is made up of a double layer of phospholipid molecules that form a fluid mosaic structure. The Phospholipids have a hydrophobic (water repelling) tail made of fatty acids and a hydrophilic (water loving ) head made of a phosphate group. 
• These phospholipid molecules in cell membrane are arranged in such a way that the hydrophobic tails face inward towards the cell’s interior and the hydrophilic heads face outward towards the Extracellular environment.
• Animal cell membrane also contains a variety of proteins. Some proteins act as receptors  by allowing the cell to sense and respond to signals from its environment. Other proteins of cell membrane act as channels by allowing molecules to enter and exit the cell, it also act as pumps by  actively transporting molecules across the membrane.
• Animal cell membrane is selectively permeable.It controls what can enter and exit the cell. Selective permeability achieved through different types of protein channels and pumps. it allows specific molecules to pass through the membrane while blocking others. For example – Animal cell membrane contains ion channels that allow ions such as sodium and potassium to pass through while blocking the passage of larger molecules such as glucose.
• Animal cell membrane also plays an important role in cell-to-cell communication and interaction. Cell surface receptors on the membrane allow cells to recognize and respond to signals from other cells. 
• Cell adhesion molecules of cell membrane allow cells to stick together and form tissues.

Also Check – 9 Important Differences Between Plant Cell and Animal Cell

Cytoplasm

• Cytoplasm of an animal cell is the gel-like substance that fills the cell and surrounds the cell’s organelles.
• It is composed mostly of water and dissolved ions, as well as various organic molecules and enzymes. 
• Cytoplasm also contains cytoskeletal elements that helps to maintain the cell’s shape and allow for movement.
• Cytoplasm is the site of many cellular processes like metabolism and protein synthesis.

Also Check – Cell Organelles – The Complete Guide

Nucleus

• Nucleus is a central organelle of the Animal cells. 
• Nucleus is spherical or oval shaped in structure . 
• Nucleus contains the cell’s DNA. DNA is organized into chromosomes. Chromosomes are long strands of DNA that contain the cell’s Genetic information. 
• This genetic information is responsible for controlling the cell’s growth, development and Reproduction. 
• Chromosomes are located in the nucleus during Interphase and are visible only during prophase of Mitosis and Meiosis.
• Nucleus also  plays an important role in  controlling the cell’s activities through the regulation of gene expression. Gene expression is the process by which the cell’s DNA is used to make proteins and other molecules that are essential for the cell’s survival. 
• Nucleus contains several regulatory proteins that help to control gene expression . It includes transcription factors and chromatin remodeling proteins.

Also Check – What are the Similarities between Plants and Animals Cells?

Nucleolus

• Nucleus also contains several important organelles like the nucleolus. 
• Nucleolus is a small, dense structure that is responsible for the synthesis and assembly of Ribosomal RNA (rRNA) and proteins.
• Ribosomes are the structures responsible for protein synthesis that are composed of rRNA and proteins.

Nuclear Envelope 

• Nucleus is  surrounded by a double membrane called the Nuclear envelope. 
• Nuclear envelope is composed of two lipid bilayers, outer and inner membranes. 
• THe outer and Inner membrane are  separated by a narrow space called the Perinuclear Space. 
• Nuclear envelope is responsible for separating the cell’s genetic material (DNA) from the rest of the cell’s contents.
• It helps to maintain the integrity of the genetic information.

Ribosomes

1. Ribosomes in animal cells are responsible for the synthesis of proteins in the cell.
2. Ribosomes play an important role in  the proper function and growth of the cell.
3. In Animal cells Ribosomes are composed of two subunits- Large subunit and a Small subunit. Large subunit contains the Peptidyl Transferase Enzyme. It is responsible for catalyzing the formation of peptide bonds between amino acids during protein synthesis. 
4. Small subunit contains the site where the amino acids are brought together and the peptide bond is formed.
5. Ribosomes can be found in two different locations within the cell –  In cytoplasm – where they are free-floating or attached to the endoplasmic reticulum (ER). These ribosomes are responsible for the synthesis of proteins that will be used within the cell or secreted outside of the cell. Other ribosomes are located on the surface of the mitochondria and chloroplasts. They are responsible for the synthesis of proteins specific to those organelles.

Cytoskeleton

• Cytoskeleton is a network of protein fibers that provides structural support and organization to the cell. 
• It is composed of three main types of fibers – Microfilaments , Intermediate filaments and Microtubules.
• Microfilaments- Microfilaments are the thinnest of the three types of fibers. They are made up of the protein actin. They are responsible for cell movement, including cell division and cell migration. Microfilament plays an important role in maintaining the shape of the cell and in cell signaling.
• Intermediate filaments- Intermediate filaments are thicker than Microfilaments. They are made up of a variety of different proteins, including vimentin and keratin.Intermediate filaments provide mechanical strength to the cell and help to resist stress and tension. They also play a role in cell signaling and in the organization of the cell’s nucleus.
• Microtubules- Microtubules are the thickest of the three types of fibers and are made up of the protein tubulin. They play an important role in cell division by organizing the chromosomes and separating them during mitosis. Microtubules also help to maintain the shape of the cell and to transport molecules and organelles within the cell.

Endoplasmic Reticulum (ER)

• Endoplasmic Reticulum is a network of tubules and flattened sacs that are located throughout the cytoplasm.
• It is responsible for protein synthesis and lipid metabolism. 
• Endoplasmic Reticulum is divided into two types – Rough Endoplasmic Reticulum (RER) and Smooth Endoplasmic Reticulum (SER). 
• Rough Endoplasmic Reticulum is studded with ribosomes. They play an important role in  protein synthesis.Smooth Endoplasmic Reticulum plays an important role in lipid metabolism.

Also Check – 6 Important Difference between Rough and Smooth Endoplasmic Reticulum

Golgi apparatus

• The Golgi apparatus plays an important role in modification, sorting,  packaging of proteins and lipids that are produced by the cell. 
• Golgi apparatus is  located near the nucleus .
• The Golgi Apparatus  is composed of a series of stacked, flattened cisternae . Cisternae are membrane bound compartments that are arranged in a curved shape. 
• Golgi apparatus also plays an important role in the formation of lysosomes. 

Mitochondria

• Mitochondria are the powerhouses of the Animal cell . They are responsible for producing energy in the form of ATP. 
• Mitochondria are found in the cytoplasm and have their own DNA and protein-synthesizing machinery.
• Mitochondria has a unique double membrane structure – outer membrane and an inner membrane. 
• Mitochondria contain their own DNA and ribosomes. It allows Mitochondria to produce some of their own proteins. 
• The main function of mitochondria is to generate energy in the form of ATP through the process of cellular respiration. 
• Mitochondria also plays an important role in the regulation of cellular metabolism and the regulation of the cell cycle. 

Also Check – 10 Important Functions of Mitochondria

Lysosomes

• Lysosomes are small, spherical organelles that are found in Animal cells. 
• They are also called Garbage disposal Units of the cell🙂. They are responsible for breaking down and recycling cellular waste materials like old or damaged cell parts, bacteria and other unwanted materials.
• Lysosomes are formed in the Golgi apparatus.
• The enzymes in lysosomes are very powerful and are able to break down a wide range of biomolecules, including carbohydrates, lipids, proteins and nucleic acids. These enzymes are also able to break down foreign substances such as bacteria and viruses that may have entered the cell.
• Lysosomes are surrounded by a lipid bilayer membrane that acts as a barrier and keeps the enzymes inside the lysosomes from leaking out and damaging the rest of the cell.

Also Check – 10 Important Difference between Cell organelles and Cell Inclusions

Centrioles

• Centriole is a Cylindrical Organelle found in the Animal Cell. 
• It is composed of microtubules. Microtubules are protein structures that provide structural support for the cell. 
• Centrioles are found in pairs and are located near the nucleus.
• In Animal cells Centrioles play an important role in cell division, specifically in the formation of the mitotic spindle. The mitotic spindle is a structure that forms during cell division and it helps to separate the chromosomes in the cell. 
• The centrioles are responsible for organizing the microtubules of the spindle.It pulls the chromosomes apart.

Also Check – Mitosis In Plant Cell and Animal Cell- Differences and Similarities

Microvilli

• Microvilli are small finger-like projections that line the surface of the animal cell membrane.
• They are responsible for increasing the surface area of the animal cell. It also helps to increase the efficiency of absorption and transport processes.
• Microvilli  are made up of an actin cytoskeleton and are covered by a plasma membrane. Microvilli are found on the surface of many types of cells For Example –  Intestinal epithelial cells, kidney proximal tubule cells,sperm cells etc. 
• In intestinal epithelial cells Microvilli plays an important role in  the absorption of nutrients from the food we eat. 
• Microvilli also plays an important role in the reabsorption of water and electrolytes in the kidney proximal tubule cells.
• Microvilli also play a role in cell-to-cell communication and interaction. They are often covered with receptors and other signaling molecules, allowing for the detection and response to chemical signals in the environment. For example, sperm cells use microvilli to sense and respond to chemical signals from the egg cell during fertilization.
• Microvilli are also involved in Cell adhesion and Motility. They are often found in clusters, called microvilli bundles that can be used to create physical connections between cells. This is especially important in the formation of tight junctions between epithelial cells that help to form a barrier between the inside and outside of the body.

Cilia

• Cilia are small, hairlike structures that line the surface of some Animal Cells. They are responsible for movement and are involved in the movement of mucus and other fluids in the body.
• Cilia are small, hair-like structures that protrude from the surface of animal cells. They are composed of microtubules and are typically about 10-20 micrometers in length. Cilia are found on the surface of many types of cells, including those of the respiratory and digestive tracts, as well as on cells of the reproductive system.
• Cilia are responsible for a variety of functions in the body, including movement, sensation and communication.
•  One of the most important functions of cilia is their role in the movement of fluids and particles through the body. Example- Cilia in the respiratory tract move mucus and trapped particles out of the lungs, Cilia in the reproductive tract move eggs and sperm towards the fertilization site.
• Cilia also play a role in cell signaling and communication.Cilia  have receptors that can sense changes in the environment like changes in temperature or chemical concentrations. 

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Also Check – 8 Important Difference between Plant Tissues and Animal Tissues

Frequently asked questions on this topic

What are ribosomes and what is their role in an animal cell?

Ribosomes are organelles that are responsible for protein synthesis. They can be found free in the cytoplasm or attached to the endoplasmic reticulum.

What is the endoplasmic reticulum and what are its functions in an animal cell?

The endoplasmic reticulum is a network of flattened sacs and tubes that is involved in the synthesis, folding and transport of proteins and lipids. It can be divided into rough and smooth ER, depending on the presence or absence of ribosomes.

What is the Golgi apparatus and what is its function in an animal cell?

The Golgi apparatus is a series of flattened sacs that is involved in the modification, packaging and transport of proteins and lipids.

What are lysosomes and what is their function in an animal cell?

Lysosomes are organelles that contain digestive enzymes and are involved in the breakdown of macromolecules, such as proteins and lipids.

What is the mitochondria and what is its function in an animal cell?

The mitochondria are organelles that are responsible for cellular respiration and ATP production.

What is the cytoskeleton and what are its functions in an animal cell?

The cytoskeleton is a network of protein fibers that provides shape, support and movement to the cell. It includes microfilaments, microtubules and intermediate filaments.

How do animal cells communicate with each other and what role does the plasma membrane play in this process?

Animal cells communicate with each other through various signaling pathways, such as the release of hormones and neurotransmitters. The plasma membrane plays a critical role in this process by regulating the movement of signaling molecules in and out of the cell.

What is an animal cell and how does it differ from a plant cell?

An animal cell is a type of eukaryotic cell that is found in animals. It differs from a plant cell in several ways, including the absence of a cell wall, chloroplasts and large vacuoles.

What is the role of the plasma membrane in an animal cell and how is it structured?

The plasma membrane, also known as the cell membrane, is a phospholipid bilayer that surrounds the cell and separates the cytoplasm from the external environment. It is selectively permeable, meaning it controls the movement of substances in and out of the cell. The plasma membrane is composed of lipids, proteins and carbohydrates and its structure includes a hydrophilic head and a hydrophobic tail.

What is cytoplasm and what are its functions in an animal cell?

The cytoplasm is a gel-like substance that fills the cell and contains various organelles, such as mitochondria, ribosomes and the endoplasmic reticulum. Its functions include providing a medium for cellular metabolism and supporting the organelles within the cell.

What is the function of the nucleus in an animal cell and what is its structure?

The nucleus is an organelle that contains the genetic material of the cell in the form of chromosomes. Its structure includes a nuclear envelope, nucleolus and chromatin. The nucleus controls cellular processes, such as DNA replication and transcription.

What is the nucleolus and what is its role in an animal cell?

The nucleolus is a dense region within the nucleus that is involved in the synthesis of ribosomes.

What is the nuclear envelope and what is its function in an animal cell?

The nuclear envelope is a double membrane that surrounds the nucleus and separates it from the cytoplasm. It contains nuclear pores that allow for the exchange of materials between the nucleus and cytoplasm.