Category: Biology Second Paper

T2 bacteriophage attaches to the cell wall of E. coli bacteria. The virus attaches to the receptive spot of the bacterium by tactile fibers. Then the tangential fibers contract. The base plate of the virus comes into contact with the cell wall of the bacteria. An enzyme called lysozyme is released from the tail of the virus. Lysozyme dissolves mucopeptides in the bacterial cell wall. As a result, a fine pore or duct is formed. This process is called drilling. Virus DNA enters the bacterial cell through pores or tubules. But the capsid coat remains outside.

The process by which virus complete their life cycle by invading and destroying bacterial cells is called the lytic life cycle. The stages of the lytic cycle of T2 phage or virulent phage are discussed.
1. Infection stage: T2 bacteriophage attaches to the cell wall of E. coli bacteria. The virus attaches to the receptive spot of the bacterium by tactile fibers. Then the tangential fibers contract. The base plate of the virus comes into contact with the cell wall of the bacteria. An enzyme called lysozyme is released from the tail of the virus. Lysozyme dissolves mucopeptides in the bacterial cell wall. As a result, a fine pore or duct is formed. This process is called drilling. Virus DNA enters the bacterial cell through pores or tubules. But the capsid coat remains outside.
2. Dormant period: Virus DNA remains inactive for 12-22 minutes after entering the host cell. During this time the DNA of the virus takes control of the genetic activity of the host.
3. Production of phage organelles: After virus DNA enters the host cell, it establishes dominance over host DNA. Then, with the help of polymerase enzymes, it uses the host nucleotides to produce new DNA. The new DNA produced makes RNA. RNA makes proteins with the help of host ribosomes. The protein molecules join together to form the capsid. Note that separate proteins are produced to form the head, tail and tangential filaments of the phage. Dr. Siddiq Publications
4. Formation of T2 Phase: Protein molecules join together to form head, tail and tangential fibers. Later these three parts join together to form the protein shell. A copy of the DNA molecule enters the brain. The tail and other parts are then joined to form the T2 phase. In this way, the bacterial cell produces numerous false virus. Finally, the synthesis of lysozyme enzyme occurs in the tail of the virus.
5. Lysis: Virus multiply inside host cells. A great stress is created in the host’s cell wall. The mucoprotein complex of the host cell wall is damaged by the action of the enzyme lysozyme. As a result, the cell wall ruptures and T2 phase is released. The breaking down of the cell wall is called lysis. Fungi of such nature are called lytic fungi or virulent fungi.
The period from when the host infects the bacterium to the formation of a full-fledged virus is called eclipse. T2 phage takes 30 minutes for virus to multiply (eclipse). During this time 300 T2 phases are generated per cell. The released new phage then invades the new host cell. Dr. Siddiq Publications

HIV is a round virus. It consists of two parts. Nucleic Acids and Capsids.
1. Nucleic Acid: At the center of the virus is a core of nucleic acid. It is called nucleoid. It is made up of RNA. At its core is reverse transcriptase. Reverse transcriptase converts RNA into DNA. It carries the genetic characteristics of the virus and plays a role in the synthesis of new viruses.
2. Capsid: The outer coat of nucleic acid is called capsid. Capsids can be spherical or polygonal. It is made up of numerous protein molecules. Each protein molecule is called a capsomer. Outside the capsid is a 1100 µm thick phospholipid bilayer. Phospholipids consist of two types of glycoproteins. GP-120 and GP-41. GP-120 helps viruses attach to host cells. GP-120 is chemically related to GP-41.

HIV is the virus that causes the deadly human disease AIDS. The virus attacks and destroys human white blood cells, macrophages and T-cell lymphocytes. It destroys the immune system of the body. In 2000, the number of AIDS patients in the world was 3.6 million. Of these, 30 lakh patients die. AIDS was first identified in 1981 by French scientists Barre Sinoussi and Luc Montneil. For this reason, they won the Nobel Prize in Medicine in 2008.
In 1983, the French scientist Dr. Lue Montagnier discovered the AIDS virus and named it Lymphadenopathy associated virus (LAV). In 1984 American scientist Dr. Robert Gallo separately discovered this virus and named it Human T-cell Lymphotropic virus, strain III (HTLV-III). In 1986, the International Committee on Nomenclature of Viruses recognized it as Human Immunodeficiency Virus (HIV).

The Greek word phage means to devour. Viruse that attack and destroy or destroy bacteria are called bacteriophages. Scientist Twort discovered it. In 1915, British microbiologist Frederick Wort discovered bacteriophage or T2 phage. In 1917, scientist D. Herreli called virus that attack bacteria as bacteriophages. T2 bacteriophage is a flagellated virus. It consists of two parts. Head and tail. Dr. Siddiq Publications
1. Head: The swollen and hexagonal part of T2 bacteriophage is called head. Its length is 93-100 nm and width is 65 nm. It is covered by a bilayer coat made of proteins. The protein coat is called capsid. Each protein molecule in the capsid is called a capsomer. The number of capsomers is 2000. The interior of the capsid is hollow. The hollow part contains a ring-shaped double-stranded DNA. The DNA segment is about 5000 nanometers in length. 50% of the total weight of T2 bacteriophage is DNA. DNA is 50 µm in length. A DNA molecule consists of 60,000 pairs of nucleotides. It contains about 150 genes. DNA carries hereditary characteristics. Brain does not have cell wall, plasma membrane, mitochondria, lysosomes, ribosomes etc.
2. Tail: The narrow and cylindrical part after the tail of bacteriophage is called tail. It is soft and flexible. Its length is 95-110 nm and diameter is 15-25 nm. It is covered by a capsid made of proteins. Inside the coat is a contractile protein. Contractile proteins contain the enzyme lysozyme. The inner part of the tail is hollow. It contains no DNA. At the end of the tail is a base plate made of proteins. The base plate has 6 long and narrow tangential fibers and several spikes or spines. Tactile fibers help bacteria move. Bacteria stick to host cells with the help of spikes or thorns. At the junction of the head and tail is a collar made of protein.
Tail does not contain cell wall, plasma membrane, mitochondria, lysosomes, ribosomes etc.
Bacteriophage T2 is one of the most well-known of the flagellar viruses. Most of the research has been done on this topic. In 1917, scientist De Herreli named this virus as bacteriophage or phage. Dr. Siddiq Publications

HIV is a round virus. It consists of two parts. Nucleic Acids and Capsids.
1. Nucleic Acid: At the center of the virus is a core of nucleic acid. It is called nucleoid. It is made up of RNA. At its core is reverse transcriptase. Reverse transcriptase converts RNA into DNA. It carries the genetic characteristics of the virus and plays a role in the synthesis of new viruses.
2. Capsid: The outer coat of nucleic acid is called capsid. Capsids can be spherical or polygonal. It is made up of numerous protein molecules. Each protein molecule is called a capsomer. Outside the capsid is a 1100 µm thick phospholipid bilayer. Phospholipids consist of two types of glycoproteins. GP-120 and GP-41. GP-120 helps viruses attach to host cells. GP-120 is chemically related to GP-41.

HIV is the virus that causes the deadly human disease AIDS. The virus attacks and destroys human white blood cells, macrophages and T-cell lymphocytes. It destroys the immune system of the body. In 2000, the number of AIDS patients in the world was 3.6 million. Of these, 30 lakh patients die. AIDS was first identified in 1981 by French scientists Barre Sinoussi and Luc Montneil. For this reason, they won the Nobel Prize in Medicine in 2008.
In 1983, the French scientist Dr. Lue Montagnier discovered the AIDS virus and named it Lymphadenopathy associated virus (LAV). In 1984 American scientist Dr. Robert Gallo separately discovered this virus and named it Human T-cell Lymphotropic virus, strain III (HTLV-III). In 1986, the International Committee on Nomenclature of Viruses recognized it as Human Immunodeficiency Virus (HIV).

The length of the TMV is about 17 times the width. Width 15-18 nm and length 280-300 nm. It consists of two parts. Nucleic acid and capsid.
1. Nucleic acid: The core of nucleic acid in the center of the virus is called nucleoid. At its center is a single-stranded RNA. The cone-shaped cavity between the patches of RNA is 4nm in diameter. RNA content in TMV is 5%. The RNA sequence is made up of 6500 nucleotides. Its molecular weight is 2.4 million daltons. It carries the genetic characteristics of the virus and plays a role in the synthesis of new viruses.
2. Capsid: The outer coat of nucleic acid is called capsid. It is made up of numerous protein molecules. It contains 95% protein. Each protein molecule in the capsid is called a capsomer. TMV contains 2130-2200 capsomeres. Each capsomer is composed of 158 amino acids. Each protein subunit has a molecular weight of 17,000 daltons. The capsid acts as an antigen and protects the acid core. Dr. Siddiq Publications

TMV is a plant virus. For the first time in 1886, Dutch scientist Adolf Mayer (Adolf Mayer) saw the mosaic disease of tobacco leaves. In 1898, the scientist Beijerinck named the tobacco leaf virus Tobacco Mosaic Virus (TMV). In 1935, scientist W. M. Stanley isolated TMV from tobacco. In 1957, scientist Smith gave another name to TMV Nicotiana virus-1.

Virus are non-trophic and contain no metabolic enzymes. However, bacteriophage has lysozyme, influenza virus has neurominidase and HIV has reverse transcriptase enzyme. Besides, virus contain enzymes like RNA polymerase, RNA transcriptase etc. Dr. Siddiq Publications