The Fundamental Unit of Life. In this video we will discuss about the fundamental unit of life. Do you know what is the fundamental unit of life?
Cell. Cell is called as fundamental unit of life. Do you know who discovered the cell?
It's Robert Hooke. In 1665, Robert Hooke absorbed a thin slice of cork under his own microscope. He found small box-like structures. They were like small rooms of a honeycomb. Robert Hooke called these boxes as cells.
The meaning of word cell is small room. Cells are the building blocks of living things. All living things are made up of cells.
Certain organisms are made up of only one cell. Such organisms are called unicellular organisms. Uni means single. Examples of unicellular organism is amoeba, chlamydomonas, paramecium and bacteria. Some organisms are made up of many cells.
Such organisms are called multicellular organisms. All multicellular organisms are developed from a single cell. Cells produce cells of their own kind by cell division. All cells come from the pre-existing cells. Do you think the whole multicellular organism is made up of single type of cells?
No. Multicellular organisms are made up of different types of cells. Now, let us see different type of cells of our body.
Muscle cells, blood cells, nerve cells, bone cell, ovum, sperm cell, fat cell. Why these cells are in different sizes and shapes? The shape and size of these cells depends on the function they perform. You know that in our body, we have different systems to perform different tasks. For example, heart pumps blood, liver secretes digestive juices, kidneys filter the blood, brain controls the body.
This means that in our body, Different jobs are done by different parts. We call this as division of labor. In this way, we will see division of labor inside a cell also. Cell is very small. Still it has so many parts in it.
The parts present in the cell are called as cell organelles. These cell organelles keep the cell alive by helping the cell in performing its tasks. Each kind of cell organelle performs a special function, such as making new material in the cell, clearing up the waste material from the cell and so on. Every living cell has the capability to perform certain basic tasks.
These basic functions are common in all living things. Cytoplasm. We have learnt that a cell is covered by a cell membrane or plasma membrane.
But what is there inside the plasma membrane? The space inside the plasma membrane of a cell is filled by a semi-transparent fluid. This semi-transparent jelly-like material is called Cytoplasm.
What does the Cytoplasm consists of? Cytoplasm consists of water, minerals and enzymes and some organelles. It is the place where many biochemical reactions take place.
There are so many organelles floating in the cytoplasm. Let us look at these cell organelles. This is smooth endoplasmic reticulum, rough endoplasmic reticulum, Golgi apparatus, lysosomes, mitochondria and vacuoles.
Each of these organelle performs a specific function. Let's see the short details of each cell organelle. Rough endoplasmic reticulum.
This is called protein factory because it makes new proteins. Smooth endoplasmic reticulum. This is called fat factory because it makes new fats.
Golgi bodies. It's called dispatch center because it handles the packaging and distribution of materials that are prepared by endoplasmic reticulum. Mitochondria. It is called powerhouse of this cell because it produces energy from glucose. Vacuoles.
They are called storage bags. They store different materials. Lysosomes.
They are called suicide bags. Because they contain the digestive enzymes and they digest the foreign materials like bacteria and damaged cells. There are some special cell organelles that are only found in plant cells. They are plastids. They are called pigment stores.
Because plastids contain different pigments. Plastids also help in photosynthesis. Now let's see why do cells have cell organelles.
Let's find the answer to this question with the help of an example. We cannot play cricket, football, basketball and tennis all together in the same court. Different courts are required to play different games. Similarly, in a cell a lot of chemical activities takes place. Different chemical activities require different conditions and machinery to take place.
All reactions cannot take place in the cytoplasm. So they need separate organelles. To keep these chemical activities separate from each other, cells use membrane bound organelles.
These organelles are called cell organelles. Can we see these cell organelles under a compound microscope? No, we cannot see the cell organelles under a compound microscope.
But cell organelles can be seen under an electron microscope. In the next video, we will learn the structure and functioning of each cell organelles. If you like the video, please give us a like and don't forget to share this video to your friends.
Subscribe to our channel for more updates and press the bell icon to get the latest notifications. The internal structure of cell. If we observe a cell under a compound microscope, we will find three important parts in it. They are plasma membrane, nucleus and cytoplasm.
In this video, we will learn about plasma membrane. Plasma membrane or cell membrane. Plasma membrane protects the inner components of the cells.
Just like how your skin protects the inner parts of your body. Plasma membrane controls the entry of the materials into the cell and exit of materials outside the cell. This works like a check post between two different states. At the check post, checking of vehicles and verification of licenses is done. In the same way, cell membrane verifies the materials and decides whether allow it or not.
It permits only the selected materials. For this reason, cell membrane is called selectively permeable membrane. Now, let us see the exchange of materials between cell and its surroundings. The exchange of gases takes place between the cell and its surroundings.
And this happens by diffusion. Do you know what is diffusion? The movement of gas molecules from a high concentration area to low concentration area is called diffusion. Here we can see the concentration of oxygen outside the cell is high compared to its concentration inside the cell.
So, the oxygen molecules enter the cell through the plasma membrane. This process is called diffusion. There is one more phenomenon through which the exchange of water takes place between the cell and its surroundings.
It is osmosis. The movement of molecules through a selectively permeable membrane is called osmosis. The movement of water molecules from a place of high concentration to a place of low concentration through a semi-permeable membrane is called osmosis. But how the other materials enter the cell? For the transfer of other materials into the cell, energy is required.
This kind of transport is called active transport. Now let us see the composition of the plasma membrane. Can we see the structure of plasma membrane through a compound microscope?
No. The structure of plasma membrane can be seen only through an electron microscope. Plasma membrane is made up of carbon compounds like lipids and proteins. Organisms like amoeba engulf the food materials through their cell membrane.
This process is called endocytosis. In the next video, we will learn about the cell wall and nucleus. If you like this video, please subscribe to our channel.
Please give us a like and share this video with your friends. Cell wall and nucleus In this video, we will see the structure and functioning of cell wall and nucleus. Both plant and animal cells have cell membrane. But plant cells have one more outer rigid cover called cell wall. Do you know with which material the cell wall is made up of?
The plant cell wall is made up of cellulose. Cellulose gives strength to the plant cells. Sometimes plant cells undergo plasmolysis. Do you know what is plasmolysis? The water present in a living plant cell is lost through osmosis and then the contents of the cell shrink away from the cell wall.
This phenomenon is known as plasmolysis. Nucleus. Now let us look at the structure of nucleus. The nucleus is covered by a nuclear membrane. This nuclear membrane has two layers.
The nuclear membrane also has pores. Materials enter and exit the nucleus through these pores. The nucleus has chromatin.
Do you know how the chromatin looks like? It just looks like a tangled thread. But it changes into rod-like structures called chromosomes during cell division. Chromosomes contain DNA and protein. Let us look at an example to understand the functioning of chromosomes.
Your phone has software to control its functioning. In the same way, every cell has DNA to control their functioning. Our phones have different apps to execute different tasks. In the same way, DNA has different genes to execute different tasks.
Functional segments of DNA are called genes. Do all cells have a distinct nucleus? No. In certain single-celled organisms like bacteria, the nuclear membrane is absent. The nuclear region is undefined and contains only nucleic acids.
Such type of nucleus is called nucleoid. The organisms whose cells lack a nuclear membrane are called prokaryotes. Pro means primitive or primary. Karyote means carry-on.
Then what are the cells with a clear nucleus called? Eukaryotic cells. Are there any other differences between prokaryotic and eukaryotic organisms?
In prokaryotes, beside the absence of nuclear membrane, the membrane-bound organelles are also absent. On the other hand, the eukaryotic cells have a nuclear membrane as well as membrane-enclosed organelles. So by this, we understand that prokaryotic organisms have poorly organized cell organelles compared to eukaryotic organisms.
Endoplasmic reticulum. In this video, we will see the structure and functions of endoplasmic reticulum. First, let us locate the endoplasmic reticulum inside the cell. Yes.
This is endoplasmic reticulum. We can see that it is located around the nucleus. This looks like a network of tubes and sheets.
It is made up of some special membrane. This membrane of endoplasmic reticulum is similar in structure with the plasma membrane. The endoplasmic reticulum is of two types. This is rough endoplasmic reticulum and this is smooth endoplasmic reticulum. The rough endoplasmic reticulum is like a network of sheets folded around.
There are so many dot-like structures present in the rough endoplasmic reticulum. These dot-like structures are ribosomes. Under the microscope, the endoplasmic reticulum with ribosomes has a rough appearance. So, that's why endoplasmic reticulum with ribosomes is called rough endoplasmic reticulum. Now, let's see the function of rough endoplasmic reticulum.
Rough endoplasmic reticulum makes new protein molecules with the help of ribosomes. That's why rough endoplasmic reticulum is also called as protein factory. Then what is the function of smooth endoplasmic reticulum? Smooth endoplasmic reticulum manufactures new fat molecules.
What happens to the new proteins and lipid molecules? made in the endoplasmic reticulum. These proteins and fats are used by cell in different ways. These materials are used to make cell membrane. We know that cell membrane is made up of proteins and lipids.
So, for the formation of new cell membrane during cell division, these materials are required. Some proteins and fats are converted to enzymes. and hormones and are secreted out of the cell to execute various functions. Apart from protein and lipid manufacture, what are the other functions of endoplasmic reticulum?
1. Endoplasmic reticulum facilitates the transport of materials between various regions of cytoplasm. It also allows the transport of materials between the cytoplasm nucleus. 2. It provides surface for many important biochemical reactions to take place.
3. In vertebrates smooth endoplasmic reticulum plays an important role in detoxifying the toxins and drugs. So these are the structural features and functions of endoplasmic reticulum Golgi apparatus. In this video, we will see the structure and functioning of Golgi apparatus.
This is Golgi apparatus. Let us observe its structure. It looks like flattened bags or vesicles. These vesicles are arranged parallel to each other and form stacks called as cisterns. Now, let us see the functions of this Golgi apparatus.
apparatus. In a factory, the machines that manufacture the item and the machines that pack the item are different. Once the items are made, then they are sent for packing and dispatch. In the same way, in our cells, protein molecules are manufactured in the endoplasmic reticulum and then they are sent to the Golgi apparatus.
for modification and for packing and dispatch. The proteins that are modified by the endoplasmic reticulum are modified, stored and when needed they are packed and dispatched in the form of vesicles. Golgi apparatus performs three important functions. 1. Storage of materials. 2. Modification of materials.
3. packaging and dispatch of materials. The Golgi apparatus gathers simple molecules and combine them to make more complex molecules. Then it take the big molecules and pack them in vesicles.
It may store these vesicles for later use or dispatch them. These vesicles are delivered to different cell organelle or sometimes These vesicles are delivered outside the cell to the target location. The lysosomes are also prepared in this Golgi apparatus.
Since these cell organelles were discovered by Camillo-Golgi, these cell organelles are called as Golgi apparatus. Lysosomes and Mitochondria In this video, we will learn about lysosomes and mitochondria. First, let us look at lysosomes in the cell. These are lysosomes. Let us see the structure and functions of lysosomes.
Lysosomes are sac-like organelles. Lysosomes are covered by a membrane outside and filled by a fluid inside. This fluid contains digestive enzymes.
Now let us see the functions of lysosomes. Their main function is to clean the waste and unwanted materials inside the cell. They work as a waste disposal system of the cells.
What kind of waste materials are found inside the cell? Sometimes a bacteria or virus or some undigested food particle enters the cell. This is considered as a waste and it has to be removed. Sometimes The parts of the cell are damaged or worn out.
These parts are also considered as a waste or unwanted material. These kind of materials are cleared by lysosomes. Sometimes if a cell is damaged, the cellular components try to repair it.
Like proteins and fats from endoplasmic reticulum, they are diverted to repair the cell. But If the damage is beyond the repair, then lysosomes help the cell to self-destruct. Lysosomes burst and the digestive enzymes present in them, they will digest the components of the cell. That is why lysosomes are called as suicide bags. Mitochondria.
These are mitochondria. Let us see the structure and functions of the mitochondria. Mitochondria are double-membraned organelles.
Each mitochondria has two membranes, one outer membrane and one inner membrane. The outer membrane is porous, that means it has pores. The inner membrane is deeply folded. Do you know why the inner membrane of mitochondria is deeply folded? Mitochondria need more surface area to carry some special reactions in which a special energy molecule called ATP is produced.
So, to provide more surface area, the inner membrane is deeply folded. Now let us see what are ATP. ATP, adenosine triphosphate, these are the energy rich molecules. In our cells, many reactions takes place and all these reactions they need energy.
And in our cell, there are so many new materials are produced. So for the production of these new materials also ATP are required. That's why ATP are called as cell currency or energy currency of cell. Generally, in a cell, nucleus has DNA and it It passes the information to the cell organelles like endoplasmic reticulum to make proteins necessary for cellular activities. That means all the cell organelles, they follow the instructions of the nucleus.
But here in case of mitochondria, it is a bit different. Mitochondria they have their own DNA and ribosomes. So they can manufacture some of their own proteins.
That's why mitochondria are sometimes called as strange organelles. This is all about lysosomes and mitochondria. Plastids and vacuoles. In this video, we will learn about plastids and vacuoles.
First, let us see the structure and functions of plastids. These are the cell organelles that are found in the blood. Only in plant cells, plastids are of two types.
1. Chromoplasts 2. Leucoplasts First we see about Chromoplasts. Chroma means colored. The plastids that have color pigments in their stroma look colored and are called as Chromoplasts.
The Chromoplasts that contain more chlorophyll and carry on photosynthesis are called as Chloroplast. So, chloroplasts are green in color due to the presence of chlorophyll. Some chloroplasts contain yellow or orange colored pigments also along with chlorophyll.
Now we see the second type of plastids, leucoplast. Leuco means white. So, leucoplasts are colorless white plastids.
Their main function is the storage of materials. Do you know what are the different materials that are stored by the leukoplast? Starch, oils and protein granules are stored by leukoplasts externally.
That means from the outside look. Plastids, they look similar to mitochondria. If we observe the internal organization of a chloroplast, the innermost membrane is folded and arranged in stacks called as grana.
The space between the grana is filled by stroma. Just like mitochondria, plastids also have their own DNA and ribosomes and can make their own proteins. Now let us see about vacuoles. Vacuoles or the sacks for storage of materials.
Materials in the form of solids or liquids are stored in them. In animal cells, the vacuoles are in small size whereas in plant cells, the vacuoles are very big and occupy 50 to 90 percent of the cell volume. How do bigger vacuoles help the plant cell? The vacuoles in the plant cell are filled with cell sap and provide turgidity and rigidity to the cell. They store many important materials like sugars, amino acids and various organic acids and some proteins.
In unicellular organisms also, vacuoles perform some important function. In organisms like amoeba, The food enters the food vacuoles where it is digested and absorbed. In the same way, contractile vacuoles are formed to collect and excrete the excess water and waste materials.
So this is all about plastids and vacuoles. Cell division. In this video, we will see the process of cell division.
We know that living things grow and reproduce. Growth means adding new cells to the body. These new cells, they come from the cell division.
To reproduce, organisms need to produce new reproductive cells or sex cells. These cells are also produced by cell division. Sometimes, Our cells may get damaged. To replace the damaged cells, new cells are required.
These cells are formed by cell division. So, cell division is important for the formation of new cells for growth, repair and reproduction. Now let us see the different types of cell division.
What are the two different types of cell division? There are two different types of cell division that is one mitosis, two meiosis. First let us see mitosis. Most of these cells are divided by this mitosis. This kind of cell division helps in the growth and repair of body.
For example, a boy grows into a man. For this, his bones and muscles are to be grown. That means growth in the bones and muscles means formation of new bone and muscle cells.
These new cells are formed by the mitosis. In the same way, for repair and maintenance of our body, new cells are required. For example, if someone falls and get their hand or leg skin bruised, in few days we see new skin is formed. This is because of the mitotic divisions of skin cells. Do you know, our skin loses 30 to 40,000 cells a day?
All these cells are to be replaced with new skin cells. So these new skin cells are formed by mitosis. In mitosis, one parent cell divides into two daughter cells.
These two daughter cells are identical and have same number of chromosomes as mother cell. For example, the number of chromosomes in a mother cell are 46. The daughter cells also will have 46 chromosomes each. But sometimes, our body needs some special cells for reproduction.
These special cells should have only half of the chromosomes of the parent cell. So, to achieve this, our reproductive cells are produced by a special method of cell division called as meiosis. The main purpose of meiotic division is to produce reproductive cells or gametes. Now let us see how this is different from mitosis. In this meiotic division, first, the parent cell divides into two daughter cells that have the same number of chromosomes as their parent.
That means, if the parent has 46 chromosomes, then the daughter cells also have 46 chromosomes. But this is not the end of meiotic division. These two daughter cells, they divide further and produces four daughter cells. These daughter cells will have half of the chromosomes as compared to the mother cell.
That means, if the mother cell has 46 chromosomes, finally the daughter cells have 23 chromosomes each. So, In meiotic division, the number of chromosomes reduces to half. The sperm cells formed in the testes of males and egg cells formed in the ovary of females are formed by meiotic divisions. So, the gametes or sex cells have half the number of chromosomes compared to the other cells of our body.
Why the sex cells have half the number of chromosomes? This is because during fertilization, A male gamete with 23 chromosomes fuses with a female gamete with 23 chromosomes and forms a zygote with 23 pairs of chromosomes that means 46 chromosomes. This zygote further divides by mitosis and develops into a baby. Please subscribe to Greatbooster channel. Press the bell icon to get all the latest updates.
Check the description to find links of other useful videos. Check the end screens for our new videos.