Definition of animal cell
Animal cell are considered to be the fundamental living species belonging to the kingdom Animalia. They are eukaryotic cells which means they possess an actual nucleus as well as organelles, which are special structures which perform various functions. Animal cells don’t have specific organelles for plants, such as cell walls that support the plant cell or the chloroplasts, an organelle that is responsible for photosynthesis.
Animals are a huge collection of living creatures which comprise three quarters of all species of earth. They are able to move, react to stimulus, react to changes in the environment, and adapt to various forms of defense mechanisms for food and reproductive processes, each of of these processes are enhanced by the components in the body. But, animals are not able to make their own food, as do plants and , therefore, they rely on plants in a way or another.
Every living thing is composed of cells that form your body’s structures. Certain living creatures are unicellular (unicellular) as well as other species that comprise multiple cells (Multicellular). A cell is the smallest (microscopic) structural-functional unit of life of an organism. The cells of animals are referred to as Animal cells, and the ones which make up plants are referred to as plant cells.
The majority of cells are covered with a membrane of protection called the cell wall. It helps shape the cells and stiffness. Because animal cells do not have an unsteady cell wall, they are able to grow the widest range of tissues, cell types and organs. The muscles and nerves are made of specific cells that plant cells are unable to develop into, thus providing these muscle and nerve cells an ability of moving.
Overview of Animal Cells
Plants, animals, fungi and protists are comprised of at the very minimum one eukaryotic cells. However archaea and bacteria comprise one prokaryotic cell.
Every cell is surrounded by cells that are surrounded by a membrane (also known as plasma membrane). The cell membrane forms the boundary that divides the cell’s interior and the exterior of the cells. The plasma membrane covers all cell components which are suspended within an emulsion-like fluid known as the cytoplasm. The cytoplasm is the place of organelles.
Eukaryotic cells differ from prokaryotic cells due to their presence in a distinct nucleus, as well as other membrane-bound organelles like mitochondria, endoplasmic-reticulum and the Golgi apparatus. Prokaryotic cells don’t have an identified nucleus (instead there is a space in the cytoplasm, known as the nucleotide holds all the DNA). They also do not have membrane-bound organelles.
Animals are multicellular and multicellular, which means that many cells are collaborating to create the entire organism. In multicellular organisms, like humans the cells may be extremely specialized to carry out various tasks. Therefore, they can behave and look very different from each other, even though they’re the same human cells.
Animal cell size and shape
Animal cells are found in a variety of shapes and sizes with sizes ranging in size from millimeters all the way to micrometers. Largest animal cells are an ostrich egg with a diameter of 5 inches that weighs 1.2-1.4 kg. The tiniest cell in the animal kingdom is a neuron that measure around 100 microns in size.
The animal cells have a smaller size than plant cells , and they tend to be irregular in their shape and take on various shapesdue to the absence of cell walls. Certain cells are oval, round rod-shaped, flattened, or concave, spherical or rectangular. The reason for this is the absence of an outer cell wall. Be aware that most cells are microscopic, which means they are only visible under a microscope to observe their anatomy.
Animal cells also share organelles of the cell with plants because both evolved from cells that are eukaryotic. As we have mentioned the animal cell is an eukaryotic cells that have a nucleus bound to membrane. They also have its genetic materials in DNA contained within the nucleus. They also have various organelles structurally located in the plasma membrane, which serve a variety of specific roles for normal cell function and to keep the body functioning normally. processes.
Animal Cell Types
There are a variety of cells from animals, all created to perform a specific function. The most popular kinds comprise:
- Skin Cells: Melanocytes, keratinocytes, Merkel cells and Langerhans cells
- Muscle Cells: Myocyte, Myosatellite cells, Tendon cells, Cardiac muscle cells
- Blood Cells: Leukocytes, erythrocytes, platelet
- Nerve Cells: Schwann cell, glial cells etc
- Fat Cells: Adipocytes
Animal Cell Diagram and Structure
The cell of the animal is composed of a variety of structural organelles that are enclosed within the plasma membrane. These organelles allow it to function effectively by triggering mechanisms that are beneficial to those who are the hosts (animal). The interaction of all cells provides an animal the capacity to move, reproduce as well as respond to stimuli in a way, take in and digest food, etc. In general, the effort put forth of all animal cells is what provides the regular working of the human body.
List of Animal cell organelles
- Plasma membrane (Cell membrane)
- Endoplasmic Reticulum (ER)
- Golgi apparatus (Golgi bodies/Golgi complex)
- Cilia and Flagella
Plasma membrane (Cell membrane)
Definition of Plasma membrane (Cell membrane)
It’s a thin, semipermeable layer of protein membrane that is surrounded by the cell of an animal.
Structure of Plasma membrane (Cell membrane)
The thin membrane is semi-permeable. It has a proportion of lipids, creating an impermeable barrier between cells and their surroundings. It also contains some proteins. It’s very consistent throughout the cell. Every living cell has the plasma membrane.
Functions of Plasma membrane (Cell membrane)
- To protect and enclose the content of the cell
- It also regulates the molecules that enter and out of cells through the membrane. This is why it regulates homeostasis.
- The proteins are active in the transportation of substances across the membrane
- The proteins and lipids enable cell communication, as do carbohydrate (sugars as well as sugar chains) are used to decorate the lipids and proteins and assist cells in recognizing one the other.
Definition of Nucleus
It is a spherical-shaped organelle that is located in the middle of cells and is enclosed by a double-layered membrane, which separates it from cells’ cytoplasm. It is anchored to the cytoplasm through the help of microtubules and filaments. It is also home to other organelles in the cell such as nucleosomes, nucleolus and chromatins. Cells have one nucleus, which divides to produce multiple nucleated cells e.g. the fibers of skeletal muscle cells. Certain cells shed their nuclei during maturation e.g. those that make red blood cells.
Structure of Nucleus
The membrane with two layers can be described as a continuous conduit membranous that originates from the endoplasmic network. The membrane is porous and permit entry of large molecules. Nucleoli (Singular Nucleolus) are tiny or small bodies that are found within the nucleus. The nucleus as well as its constituent organelles are suspended inside the nucleoplasm (House of the chromosomal DNA as well as genetic material)
Functions of Nucleus
- The main function for the nucleus’s role is to regulate and regulate the activities of cells during growth and to maintain metabolism of cells.
- It also contains genes that carry the hereditary information in the cell.
- The chromosomal DNA as well as genetic materials that are composed of genetic coded end up making the amino acid sequences, which are utilized by cells.
- The nucleus, therefore, is the information center.
- It is the place where Transcription takes place (formation of mRNA out of DNA) and the mRNA gets transported into within the nucleus.
It’s a gel-like compound that houses all cell organelles, which are enclosed in cells’ membranes. Organelles that are included include: Mitochondria endoplasmic Golgi apparatus, reticulum microfilaments, intermediate filaments of lysosomes microtubules and Vesicles.
Definition of Mitochondria
They are membrane-bound organelles found within the cell cytoplasm in all eukaryotic cells. The amount of mitochondria present in every cell is different according to the purpose of the cell that it serves. For instance, erythrocytes may not contain mitochondria, whereas the muscles and liver cells contain hundreds of mitochondria.
Structure of Mitochondria
They can be rod-shaped, oval or spherically formed and have a diameter that ranges from 0.5 to 10 millimeters. Mitochondria are composed of two distinct membranes, the outer and the inner membrane. They also have a mitochondrial gel-matric within the middle mass. The membranes are bent into folds, referred to as the cristae.
Functions of Mitochondria
- Their main purpose is to provide energy to cells i.e they function as power generators. They generate energy in the form of Adenosine Tri-phosphate (ATP), by converting oxygen and nutrients into energy that allows cells to fulfill their job and also to let excess energy out of the cell.
- Mitochondria are also a source of calcium, which aids in cell signaling by generating mechanical and cellular heat, as well as mediating cell expansion and dying.
- The membrane’s outer layer is permeable and allows for small molecules to be transported as well as a channel that can move large molecules.
- The membrane of the mitochondria’s inner membrane is less permeable and allows tiny molecules to enter the mitochondrial gel matrix in its central region. It is comprised of mitochondria’s DNA and enzymes that aid in the Tricarboxylic Acid (TCA) cycle or the Kreb’s Cycle.
- The TCA cycle is a process that uses up nutrients, and converts them into by-products which the mitochondria utilize to generate energy. The process takes place within the membrane’s inner layer because the membrane is bent into folds, known as the cristae. in which the protein components are used to make the primary cells of the energy production system, called known as the Electron Transport Chain (ETC). ETC is the major source of ATP production in the body.
- The ETC comprises a variety of oxidation-reduction reactions that transport electrons across proteins from one component to the next which generates energy to phosphorylate ADP (Adenosine diphosphate) to ATP. This is known as the chemiosmotic co-coupling of oxygenative phosphorylation. This mechanism provides energy to a variety of cell activities, such as muscle movement, and they help to boost the general brain function.
- Certain proteins, if not all and the molecules that compose the mitochondria originate from the nucleus of cells. Its mitochondrial genome contains 37 genes of which thirteen of them produce the majority of the components of ETC. But mitochondrial DNA is extremely susceptible to mutations since they do not possess a substantial repair mechanism for DNA. This is an element that is common to other DNAs in the nuclear chain.
- Additionally, Reactive Oxygen Species ((ROS)) often referred to as free radicals can be found within the mitochondrion as a result of the tendency to abnormal release of free electrons. The electrons that are produced get neutralized when antioxidants are present within the mitochondrion. However, certain free radicals may harm mitochondrial DNA (mtDNA).
- Consumption of alcohol may cause damage to mitochondrial DNA because excessive alcohol in the body triggers the overproduction of detoxifying enzymes, resulting in the release extremely reactive electrons across the cytoplasmic membrane, and eventually into mitochondrial matrix, when they combine with other molecules in the cell, producing a myriad of radicals that cause cell destruction.
- The majority of organisms inherit mtDNA of their mother. This is because the mother’s egg provides the bulk parts of the cytoplasm that is transferred to embryos. However, mitochondria that are inherited from the father’s sperm are destroyed. This results in the emergence of mitochondrial diseases that are acquired or inherited because of mutations that are transmitted to the embryo through the paternal and maternal DNA, or the maternal mtDNA. The diseases that are affected include Parkinson’s disease and Alzheimer’s disease. The accumulation of mutated mtDNA over time, it has been linked to aging as well as the formation of cancers as well as illnesses.
- Naturally mitochondria play an important part in the process of programmed cell death (apoptosis) and because of mutations in mtDNA that stop cell death and cause the development of cancer.
Definition of Ribosomes
They are tiny organelles that are composed by 60% of RNA in the cytoplasm granules, and 40% proteins. In all living cells, ribosomes are present that are circulating in the cytoplasm, and they may be bound to the endoplasmic-reticulum. This is the place where protein synthesis takes place.
Structure of Ribosomes
Ribosomes consist of ribosomal proteins as well as an RNA molecule called ribosomal (rRNA). In eukaryotic cells, they are half ribosomal DNA in addition to half ribosomal proteins. The ribosome is composed of two parts i.e. one large subunit as well as a small subunit , each with its distinctive forms. The subunits are referred to by the 1940s as well as the 60s in the cell of an animal.
Functions of Ribosomes
- Ribosomes which form free particles are connected to the endoplasmic membrane in huge numbers making up about one quarter of cell organelles. A single cell with a replicated copy contains about 10 million Ribosomes.
- The ribosomal subunits serve as the place where genetic code is encoded into proteins. In ribosomes, MRNA is the one that determines the coding transfer RNA (tRNA) which in turn determines the amino acids in the protein sequences. This results in the creation of rRNA, which is involved in the catalyzing of peptidyl transferase , which creates the peptide bonds between amino acid sequences that make the proteins. The proteins formed are then released from ribosomes and migrate to other cells to be utilized by cells.
Endoplasmic Reticulum (ER)
Structure of Endoplasmic Reticulum (ER)
It is a continuous membranous organelle folded in the cytoplasm. It is comprised of an incredibly thin and flattened network of connected compartments (sacs) that connects the cytoplasm to the nucleus. Inside its membranes membranous spaces known as the cristae spaces . These spaces as well as the membrane folding process is called the cristae. There are two kinds of ER according to their structure as well as the role they fulfill, which includes the Rough Endoplasmic Reniculum as well as the Smooth endoplasmic Reticulum.
Functions of Endoplasmic Reticulum (ER)
- Manufacturing, processing , and transporting proteins that are essential for the utilization of cells within and out of cells. This is due to the fact that it is directly linked with the nucleus, allowing an avenue between the nucleus as well as the cell cytoplasm.
- The ER contains more than half of the membranous cells, which means it has a huge surface area on which chemical reactions occur. They also have the enzymes that are responsible for the majority of cell lipid synthesis , and therefore are the main site for the synthesis of lipids.
The differences in functional and physical features differentiates those who have ER into two kinds i.e rough endoplasmic reticulum as well as smooth endoplasmic-reticulum.
Types of Endoplasmic Reticulum
- Rough Endoplasmic Reticulum (Rough ER) – The ER that is rough is referred to as “rough” because its the surface is covered by the ribosomes that give rough appearance. The purpose of the Ribosomes that reside on the their rough ER is to synthesize proteins. They are equipped with a signaling pathway, sending them to the reticulum of the endoplasmic ring to process. The rough ER transports proteins and lipids throughout cells into the cristae. They then go to the Golgi bodies or placed inside the cell membrane.
- Smooth Endoplasmic Reticulum (Smooth ER) – Smooth ER is not connected with ribosomes. Their function differs from that of the endoplasmic reticulum although it is located close to the endoplasmic reticulum. It’s role is to produce of lipids (cholesterol as well as phospholipids) which are used for creating new cell membranes. They also play a role in the production of steroid hormones made from cholesterol in certain cell types. They also aid in the liver’s detoxification following the consumption of toxic chemicals and drugs.
Additionally, there is a specific kind of smooth ER, known as the sarcoplasmic retina. Its role is to control the level of Calcium ions within the muscle cell’s cells’ cytoplasm.
Golgi apparatus (Golgi bodies/Golgi complex)
Structure of Golgi apparatus (Golgi bodies)
They are cell organelles that are bound to membranes. They can be that are found in the cytoplasm an eukaryotic cell. They are located next to the endoplasmic retina and close to the nucleus. Golgi bodies are surrounded by microtubules in the cytoplasm and held by a protein matrix . It is composed of flattened pouches that are referred to as cisternae.
These cisternae can range from 4-10 in size for Golgi cells of animal cells but some single-celled organisms can have around 60 cisternae. They are comprised of three main compartments referred to as the cis (Cisternae closest to to the Endoplasmic Reticulum) and medial (central layers of cisternae) and trans (cisternae further away from the endoplasmic Reticulum). Animal cells possess a few (1-2) Golgi bodies , whereas plants have around a hundred.
Functions of Golgi apparatus (Golgi bodies)
- They are primarily used to transport protein, modify it and then pack it and lipids in the Golgi vesicles, which then transport them to their intended locations. Animal cells have several Golgi bodies, while plants have only a few hundred.
- Cis as well as the trans Golgi network form the upper layer of cisternae that lies between the trans and cis faces and are responsible for sorting proteins as well as fats that are received by the cis face , and released from the trans face, and by the Golgi bodies.
- The cis surface collects the lipids and proteins of the vesicles fused in clusters. The vesicles fused are able to are transported along microtubules to the specialized area known as the vesicular tubular cluster. This is a space between the endoplasmic as well as the Golgi apparatus.
- The vesicle clusters join the trans Golgi network, which carries proteins and lipids into Cisternae on the cis side. As they shift from the face of the cis to the faces of trans, they are transformed into functional units. These functional units are then transported to extracellular and intracellular cells.
- Modification mechanisms comprise:
- Cleaving of chains of oligosaccharides
- Sugar moieties are attached to various side chains
- The addition of fatty acids or groups of phosphates by phosphorylation or removing monosaccharides e.g. the removal of mannose moieties is done in the cis as well as the medial cisternae, while the addition of galactose is done inside the trans-cisternae.
- Sorting of modified proteins , lipids and proteins is carried out within the trans-Golgi system and is packed into trans vesicles. The vesicles then sends them to the Lysosomes, or occasionally into the cell membrane to allow exocytosis. Facilitated by ligands attached to receptors, causing an fusion reaction and the secretion of proteins.
It’s also called cell vesicles. Lysosomes were first discovered through Christian Rene de Duve, an Belgian Cytologist in the 1950s.
Structure of Lysosomes
They are round subcellular organelles that are found in nearly all cells of the eukaryotic family. Lysosomes can be described as extremely acidic organelles, containing digestive enzymes, and every lysosome is enclosed by a membrane that protects it from the external environment.
Functions of Lysosomes
- This is where you can find the digestion of cells’ nutrients, excretion and cell renewal.
- Lysosomes break down macromolecules and components that are found outside the cell into smaller components that are then carried to the cytoplasm through an electron pump. This is used to construct new cell materials.
- These macromolecules are composed of parts and cells from the past of cell waste products microorganisms, cell debris.
- The digestive enzymes that are found in lysosomes are known as acid hydrolases or hydrolytic enzymes that break down massive molecules into smaller molecules that are then utilized by cells.
- They also breakdown large molecules, e. carbohydrates, proteins and lipids into smaller molecules e.g. simple sugars and amino acids as well as fatty acids.
- Notice That the enzymes work only inside the acidic lysosome. The acidity prevents cells from being destroyed in the event of lysosomal leakage due to the fact that the pH of cells is between neutral and slightly alkaline.
Structure of Cytoskeleton
It’s a fibrous system made up of and by various proteins that form lengthy chains of amino acids. These proteins are located in the in the cytoplasm of eukaryotic cells. They are made up of three kinds of tiny filaments that include The Actin filaments (Microfilaments) Microtubules Intermediate filaments.
Functions of Cytoskeleton
- The cytoskeleton is responsible for creating an organized network of cells components, and also to keep the shape of the cell.
- It also allowed for a consistent motion of the cell as well as its organelles by the filament system that is found in the cell’s cell cytoplasm.
- It also organizes the cell components to maintain the cell’s shape
- It is a key player for the motion of cells and certain organelles of the cell in the cytoplasm.
- The tiny filaments comprise:
- Actin filaments; Actin filaments, also known as microfilaments. It’s an interconnected network of fibers that run parallel to one another. they play a major function in giving cells its shape. They alter continuously, assisting cells to move as well as facilitate certain cell functions such as adhesion ability to substrates as well as cleavage mechanisms during the mitotic cell division
- Microtubules– Microtubules are the long filaments that aid in mitosis, moving daughter chromosomes from the original daughter cells.
- Intermediate filaments– Intermediate filaments are more stable filaments as compared to microtubules and actin. They constitute the real cell skeleton, and they keep the nucleus in its proper place inside the cell.
- It also enhances the cell’s elastic factor to enable it to withstand physical stress.
- Other proteins that can be added to the cytoskeleton of cells comprise septin (assembles the filaments) and spectrin (help to maintain the shape of cells by bringing together the cell membrane and the intracellular membrane of the cell).
Structure of Microtubules
These are straight, long hollow cylinder filaments which consist of 13-15 subfilaments (protofilament) string of a specific tubulin-like globular protein only found in eukaryotic cell. They are present in the cytoplasm within the animal cell.
Functions of Microtubules
- Organelles that transport certain organelles, such as mitochondria and vesicles i.e. transporting vesicles from the cell to tips of the axons, and then back to the cell body.
- Structural support. They provide particular support to Golgi bodies, keeping them in the gel matrix of the celluloid.
- They form the rigid and well-organized component of the cytoskeleton cell, allowing it to assume a certain shape.
- They are the principal components that form the locomotive projections in cells (cilia as well as flagella)
- They also play an important role in the creation of the spindle fibers of chromosomes of the cell when the mitotic cell division.
It is found specifically within the cell of an animal which is able to duplicate or create copies on its own. It’s comprised of 9 microtubule bundles . their main function is to help in coordinating the process of cell division.
Structure of Centrioles
It is a tiny structure made up of nine microtubules that are arranged in groups of three , which is why they are known as triplet microtubules. Because they are triplets, they are extremely solid and are observed within structures like cilia or flagella. The microtubules that make up the triplet are joined by proteins, which gives the centriole shape. They are found inside the centrosome and are responsible for creating and holding microtubules in the cell. The microtubules of the triplet are enclosed by a pericentriolar structure that is populated with molecules that make up microtubules. Each microtubule of the triplet microtubule structure is comprised of tubulin subunits, which connect to form lengthy hollow tubes, which appear as if they are made of straw (microtubules).
Functions of Centrioles
- The centriole microtubules facilitate the transport of compounds that are joined by glycoprotein to any cell. The glycoprotein linkage functions as a signaling device to transport specific proteins.
- The centrioles bind the microtubules which extend out from it and hold the necessary factors to form more tubules.
- Mitosis occurs through reproduction of every centriole that produces duplicates of every centriole (4 centrioles). Centrioles that have been formed break up into two centrosomes, with each centriole angled to the other centriole. The microtubules that connect the centrosomes push the centrioles’ pairs apart and to opposite ends within the cell. When the centrioles have been put in place, the microtubules stretch to the cell’s cytoplasm in search of the chromosome. Microtubules are then bound to the chromosome in the centromere. The microtubules then break away from the centriole, tearing the chromosomes away.
These are tiny bodies that are found within the celluloid.
Structure of Peroxisomes
They have a spherical form and are bound by a membrane , and are the most frequent micro-bodies that reside in cells’ the cytoplasm.
Functions of Peroxisomes
Peroxisomes are responsible for:
- Lipid metabolism
- Chemical detoxification is the process of the removal of hydrogen atoms from different oxygen molecules to create hydrogen peroxide. This neutralizes the effects of alcohol on the body.
- The mechanism it uses in the Reactive Oxygen is important.
Cilia and Flagella
They are projections of locomotives that can be found on the outside of the cell.
Structure of Cilia and flagella
They are composed of of filaments. These filaments are made up of partially and fully formed microtubules that prolong the projections. Microtubules that are partially extended don’t reach the edge of the cilium while the full microtubules reach the top of the cilium. They also have motor proteins called Dynein that form a bridge between partial microtubules and entire microtubules. The entire collection is joined as extensions of the plasma membrane of cells.
Functions of Cilia and flagella
- Sperm cells are equipped with flagella, which allows them to swim to egg for fertilization. For individual cells, like Sperm, this permits they to swim.
- Cilia inside the animal cell help move fluids away from and through cells that are immobile.
- Cilia aid in moving surface particles , particularly in the epithelial linings of the nostrils. They also move mucus on the cell’s surface.
They are vesicles that are bound to membranes and created by the process of endocytosis. They can be found within the cell’s the cytoplasm.
Structure of Endosome
Organelles membranous attached to the cell membrane.
Functions of Endosome
- Its primary purpose is to fold within the plasma membrane. It allows the diffusion of molecules through extracellular fluids.
- Their main purpose is to eliminate waste material from cells through endocytosis and the process of phagocytosis
They are organelles of cells that are filled with liquid protected by an outer membrane.
Structure of Vacuoles
They are membrane-bound sacs that reside within the cell’s in the cytoplasm. Vacuoles have only one membrane around it that is known as a tonoplast. This membrane is similar to its plasma membrane.
Functions of Vacuoles
- Their primary purpose is to store water, food as well as carbohydrate in the form sugars, and the waste material.
- Tonoplast can be described as an regulating device that controls the flow and outflow of proteins that are small across the pump
- is the guardian for the kinds of things that can be accessed out of vacuoles
- They also remove harmful substances and waste material from the cells as security measures.
- They also eliminate weakly folded proteins from cells.
- Vacuoles can also be used modify their function to fulfill the roles to the cell by changing the shape and size.
They are protrusions that appear on the surface within the intestinal lining on the egg cell’s surface, as well as on white blood cells.
Structure of Microvilli
They are surface protrusions that are formed by the accessory proteins of filaments of actin. The accessory proteins join to form microvilli that are located on the surface of the cell membrane.
Functions of Microvilli
- Within the small intestines they enhance the surface to allow the absorption of digested foods and water. There are microvilli in the ear to detect of sound. They transmit sounds to the brain using an electrical signal.
- They also aid in anchoring the egg’s sperm to facilitate fertilization.
White blood cells serve as anchors that allow the white blood cells circulate throughout the system, allowing them to connect to pathogens.