 So, we will continue with the general properties of the viruses. As we already know that viruses are non-living organisms, non-cellular, and contain a protein called the capsid, which is surrounding the genetic material of the virus. Similarly, some of the viruses have the envelope and some don't have the envelope. Because they are the non-living structures, because they need the host machinery to replicate. If they don't have the host, they don't have their own machinery to replicate by themselves. Similarly, they have a nucleic acid, the nucleic acid may be the RNA or DNA, ribonucleic acid or deoxyribonucleic acid, or maybe the both of them are inside them. They are capable to be producing only if they are inside the host. If they are not inside the host or they are not attacking the host, they will not be capable of reproducing themselves. Some viruses are enclosed in a protective envelope. Actually, the viruses are made up of three things, RNA, capsid and enveloped are non-enveloped. Some of the viruses have the envelope, which is protective coat and which is protecting and surrounding the capsid. Some viruses may have the spikes on the envelope. These spikes are helping to attack the host cell, because attaching an entry and attachment of the host cell is very important for the life cycle of the viruses. Most of the viruses are specific. For example, if some of the viruses need to attack the bovine animals, then they will only attack the bovine animals. They will not attack the equines or the felines. Similarly, if some of the specific for the felines, then they will not attack the human beings. Morphology of the viruses. As we already studied that actually virus is made up of three things. Sometimes two things, the RNA or DNA, the nucleic acid, the capsid, which is present, which is surrounding the nucleic acid and protecting the nucleic acid. And then enveloped are non-enveloped viruses. Some of the viruses are the capsid of the viruses is surrounded by some envelope. And then the envelope may also contain the spikes. Viruses come in a variety of the shapes. Some of them are helical in shape. Some of them are iso, icosahedral in shape, just like the Ebola viruses, they are helical. The same are polyhedral shapes, just like the, we can take the example of the influenza virus, which is the polyhedral. And then the others are the complex shapes like the bacteriophages. Bacteriophages are also containing the structure, which is helical in shape, while the icosahedral symmetry. Just to take example of some of the viruses, and we can see their pictures, their diagrams just on the left side is the virus, which is helical in shape. Just like we take the example of Ebola virus. So it contains the nucleic acid, then the capsid, capsids are made up of the capsomeres in this case. On the other side is the electron microscope shape. You can see of the same virus, Ebola virus. Then are the polyhedral viruses. Polyhedral viruses are actually having different corners. We take the example of the adenovirus, the mast adenovirus here you can see on the left side is actually the shape, the corners, which are very clear from this. It contains the nucleic acid and the capsid, which is again made up of capsomeres. And then the electron microscope, you can see that how the mast adenovirus looks like. Then there are some very complex viruses just like we take the example of the bacteriophages. Here is also the even bacteriophage example is given. It has the capsid, which is about 65 nanometer. And then it has the DNA inside, this is the DNA virus. And then the sheet, which is actually the helical in shape. At the same time, the capsid of the virus, which is containing the nucleic acid, that will be the icosahedral in shape. Then it also contains the tail fibers and pin base plates also present in the bacteriophages. This is the only ability of the bacteriophages that they are really very complex and very difficult for them to handle them. And then similarly, the electron microscope shape is also there.