Embedded Files
Cells are the basic building blocks of all living things. The human body is composed of trillions of cells. 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.
Cells have many parts, each with a different function. Some of these parts, called organelles, are specialized structures that perform certain tasks within the cell.
Cell
Characteristics of Cells
Following are the various essential characteristics of cells:
Cells provide structure and support to the body of an organism.
The cell interior is organized into different individual organelles surrounded by a separate membrane.
The nucleus (major organelle) holds genetic information necessary for reproduction and cell growth.
Every cell has one nucleus and membrane-bound organelles in the cytoplasm.
Mitochondria, a double membrane-bound organelle is mainly responsible for the energy transactions vital for the survival of the cell.
Lysosomes digest unwanted materials in the cell.
Endoplasmic reticulum plays a significant role in the internal organization of the cell by synthesizing selective molecules and processing, directing and sorting them to their appropriate locations.
Types of Cells
Cells are similar to factories with different laborer's and departments that work towards a common objective. Various types of cells perform different functions. Based on cellular structure, there are two types of cells: -
Eukaryotes
Prokaryotes
Type of Cell
1) Eukaryotic Cells
Eukaryotic cells have a nucleus enclosed within the nuclear membrane and form large and complex organisms. Protozoa, fungi, plants, and animals all have eukaryotic cells. They are classified under the kingdom Eukaryota.
They can maintain different environments in a single cell that allows them to carry out various metabolic reactions. This helps them grow many times larger than the prokaryotic cells
Eukaryotic cells are characterized by a true nucleus.
The size of the cells ranges between 10–100 µm in diameter.
This broad category involves plants, fungi, protozoans, and animals.
The plasma membrane is responsible for monitoring the transport of nutrients and electrolytes in and out of the cells. It is also responsible for cell to cell communication.
They reproduce sexually as well as asexually.
There are some contrasting features between plant and animal cells. For eg., the plant cell contains chloroplast, central vacuoles, and other plastids, whereas the animal cells do not.
Eukaryotic Cell
2) Prokaryotic Cells
Prokaryotic cells are single-celled microorganisms known to be the earliest on earth. Prokaryotes include Bacteria and Archaea. The photosynthetic prokaryotes include cyanobacteria that perform photosynthesis.
A prokaryotic cell consists of a single membrane and therefore, all the reactions occur within the cytoplasm. They can be free-living or parasites.
Prokaryotic cells have no nucleus. Instead, some prokaryotes such as bacteria have a region within the cell where the genetic material is freely suspended. This region is called the nucleoid.
They all are single-celled microorganisms. Examples include archaea, bacteria, and cyanobacteria.
The cell size ranges from 0.1 to 0.5 µm in diameter.
The hereditary material can either be DNA or RNA.
Prokaryotes generally reproduce by binary fission, a form of asexual reproduction. They are also known to use conjugation.
Prokaryotic Cell
Difference between Prokaryotic and Eukaryotic Cells
Though these two classes of cells are quite different, they do possess some common characteristics. For instance, both possess cell membranes and ribosomes, but the similarities end there. The complete list of differences between prokaryotic and eukaryotic cells is summarized as follows:
Difference between Prokaryotic and Eukaryotic Cells
Cell Structure
The cell structure comprises individual components with specific functions essential to carry out life’s processes. These components include- cell wall, cell membrane, cytoplasm, nucleus, and cell organelles. Read on to explore more insights on cell structure and function.
Cell structure
Cell Membrane
The cell membrane supports and protects the cell. It controls the movement of substances in and out of the cells. It separates the cell from the external environment. The cell membrane is present in all the cells.
The cell membrane is the outer covering of a cell within which all other organelles, such as the cytoplasm and nucleus, are enclosed. It is also referred to as the plasma membrane.
By structure, it is a porous membrane (with pores) which permits the movement of selective substances in and out of the cell. Besides this, the cell membrane also protects the cellular component from damage and leakage.
It forms the wall-like structure between two cells as well as between the cell and its surroundings.
Plants are immobile, so their cell structures are well-adapted to protect them from external factors. The cell wall helps to reinforce this function.
Cell membrane
Cell Wall
The human skeletal system is the internal skeleton that serves as a framework for the body.
The cell wall is the most prominent part of the plant’s cell structure. It is made up of cellulose, hemicellulose and pectin.
The cell wall is present exclusively in plant cells. It protects the plasma membrane and other cellular components. The cell wall is also the outermost layer of plant cells.
It is a rigid and stiff structure surrounding the cell membrane.
It provides shape and support to the cells and protects them from mechanical shocks and injuries.
Cell Wall
Cytoplasm
The cytoplasm is a thick, clear, jelly-like substance present inside the cell membrane.
Most of the chemical reactions within a cell take place in this cytoplasm.
The cell organelles such as endoplasmic reticulum, vacuoles, mitochondria, ribosomes, are suspended in this cytoplasm.
Cytoplasm
Nucleus
Nucleus
The nucleus contains the hereditary material of the cell, the DNA.
It sends signals to the cells to grow, mature, divide and die.
The nucleus is surrounded by the nuclear envelope that separates the DNA from the rest of the cell.
The nucleus protects the DNA and is an integral component of a plant’s cell structure.
Nucleus
Cell Organelles
Cell Organelles
Cells are composed of various cell organelles that perform certain specific functions to carry out life’s processes. The cell organelles are as follows:
Nucleolus
Nuclear membrane
Chromosomes
Endoplasmic reticulum
Golgi Bodies
Ribosome
Mitochondria
Lysosomes
Chloroplast
Vacuoles
Cell organelles
Nucleolus
Nucleolus
The nucleolus is the site of ribosome synthesis. Also, it is involved in controlling cellular activities and cellular reproduction.
Nucleus is the control center of the cell. The nucleus contains DNA or genetic material. Nucleus also contains a nucleolus, which is a structure where ribosomes are made. After ribosomes leave the nucleus they will have the important job of "synthesizing", or making, proteins. The nucleus controls and regulates the activities of the cell (e.g., growth and metabolism) and carries the genes, structures that contain the hereditary information.
Nucleolus
Chromosomes
Chromosomes are the highest level of organization of DNA and proteins. The main function of chromosomes is to carry the DNA and transfer the genetic information from parents to offspring. Chromosomes play an important role during cell division. They protect the DNA from getting tangled and damaged.
Chromosomes play a crucial role in determining the sex of an individual. Each human cells contain 23 pairs of chromosomes.
Chromosomes
Endoplasmic reticulum
The Endoplasmic Reticulum is a network of membranous canals filled with fluid. They are the transport system of the cell, involved in transporting materials throughout the cell.
There are two different types of Endoplasmic Reticulum:
Rough Endoplasmic Reticulum – They are composed of cisternae, tubules, and vesicles, which are found throughout the cell and are involved in protein manufacture.
Smooth Endoplasmic Reticulum – They are the storage organelle, associated with the production of lipids, steroids, and also responsible for detoxifying the cell.
Endoplasmic Reticulum
Golgi Bodies
Golgi Apparatus is also termed as Golgi Complex. It is a membrane-bound organelle, which is mainly composed of a series of flattened, stacked pouches called cisternae. This cell organelle is primarily responsible for transporting, modifying, and packaging proteins and lipids to targeted destinations. Golgi Apparatus is found within the cytoplasm of a cell and is present in both plant and animal cells.
Golgi bodies
Mitochondria
Mitochondria are called the powerhouses of the cell as they produce energy-rich molecules for the cell. The mitochondrial genome is inherited maternally in several organisms. It is a double membrane-bound, sausage-shaped organelle, found in almost all eukaryotic cells.
The double membranes divide its lumen into two distinct aqueous compartments. The inner compartment is called a ‘matrix’ which is folded into cristae whereas the outer membrane forms a continuous boundary with the cytoplasm. They usually vary in their size and are found either round or oval in shape. Mitochondria are the sites of aerobic respiration in the cell, produces energy in the form of ATP and helps in the transformation of the molecules.
For instance, glucose is converted into adenosine triphosphate – ATP. Mitochondria have their own circular DNA, RNA molecules, ribosomes (the 70s), and a few other molecules that help in protein synthesis.
mitochondrion
Nuclear membrane
The nuclear membrane protects the nucleus by forming a boundary between the nucleus and other cell organelles. The critical function of the nuclear membranes is to act as a barrier that separates the contents of the nucleus from the cytoplasm. Like other cell membranes, the nuclear membranes are phospholipid bilayers, which are permeable only to small nonpolar molecules.
Nuclear Membrane
Lysosomes
Lysosomes are the garbage collectors that take in damaged or worn-out cell parts. They are filled with enzymes that break down this cellular debris. Lysosomes function as the digestive system of the cell, serving both to degrade material taken up from outside the cell and to digest obsolete components of the cell itself.
Lysosomes
Chloroplast
Some organisms such as plans that are photoautotrophic meaning they capture sunlight for energy have cells with an organelle called a chloroplast. The chloroplast is where photosynthesis happens. s It's green because it has a green pigment called chlorophyll. Chloroplasts are plant cell organelles that convert light energy into relatively stable chemical energy via the photosynthetic process. By doing so, they sustain life on Earth. Chloroplasts also provide diverse metabolic activities for plant cells, including the synthesis of fatty acids, membrane lipids.
Chloroplasts
Vacuoles
Vacuoles are mostly defined as storage bubbles of irregular shapes which are found in cells. They are fluid-filled organelles enclosed by a membrane. The vacuole stores the food or a variety of nutrients that a cell might need to survive. In addition to this, it also stores waste products. The waste products are eventually thrown out by vacuoles. Thus, the rest of the cell is protected from contamination. The animal and plant cells have different size and number of vacuoles. Compared to the animals, plant cells have larger vacuoles.
Vacuoles
RBC
The Red blood cells are also called erythrocytes. RBCs store the haemoglobin, which is a respiratory pigment that binds to oxygen or carbon dioxide molecules. This helps in the transportation of the oxygen to different tissues and organs of the human body. It also takes away the carbon-dioxide from different organs and tissues to be replenished in the lungs.
Haemoglobin is mainly composed of iron, which combines with the oxygen, thus giving a reddish colour to the blood. It occupies 40-45% of the total volume of blood. The primary function of the RBCs is the transportation of nutrients and hormones throughout the human body.
Lifespan of RBC
The lifespan of RBC is 100-120 days. When their lifespan is completed, they are eliminated through the circulatory system. When a person suffers from chronic diseases, the lifespan of RBCs is reduced.
RBC
WBC
WBC-white blood cells are also called leukocytes or leucocytes. They are cells of the immune system, which is mainly responsible for:
Protecting and fighting against invading pathogens.
Stimulates the production of the progesterone hormone
Play a vital role in the human reproductive system by producing a network of blood vessels within the ovary.
On an average, the total count of white blood cells in every microliter of blood ranges between 4 and11 thousands and a healthy person will produce around 80 to 100 billions of white blood cells every day. The lifespan of white blood cells ranges between 13 and 20 days.
White blood cells are nucleotide blood cells which are white in color, hence they are called white blood cells. These blood cells are characterized into granulocytes and agranulocytes.
WBC
Page updated
Google Sites
Report abuse