VIRUSES-MEMORY CAPSULES

MEMORY CAPSULES  & MEMORY CHARTS

VIRUSES

Different types of nucleic acids present  in viruses

ss DNA	ds DNA	ss RNA	ds RNA
M13-bacteriophage QX-174 bacteriophage	Many animal viruses. T-even bacteriophages Coli phages Phyto phages--CMV,DMV	Many plant viruses TMV TNV Zoophages-polio virus, Influenza virus	Phyto phages-Wound tumour  virus,Maize rough dwarf virus,Rice dwarf virus Zoo phages-Reo virus Blue tongue virus Bacteriophage-Q6

TMV

        Shape – Rod.                                                       Length – 300 nm

        Diameter – 18 or 19 nm                                      

        No. of capsomeres – 2,130                                  Symmetry – Helical

        Type of Nucleic acid – ss RNA                          Type of virus – Phytophage

        Diameter of central hole – 4nm/40A°                 No. of amino acids in a polypeptide chain – 158

        Length of m RNA involved in the synthesis of each capsomer of TMV – 1621.8A°

        No. of nucleotides present in the mRNA involved in the synthesis of each capsomer of TMV – 477

        No. of nucleotides in the RNA – 6500               Length of RNA – 22100 A°

Bacteriophage

Ø  Length of head – 65 nm                                

Ø  Breadth of head – 95 nm

Ø  Shape of head – Hexagonal                           

Ø  Shape of virus – Tad pole

Ø  Shape of tail – Rod                                        

Ø  Type of nucleic acid – ds DNA

Ø  Length of tail – 95 nm                                               

Ø  Diameter of tail core – 8 nm

Ø  No. of capsomeres in tail – 144                     

Ø  Capsomere rings in tail – 24

Ø  Shape of the tail plate – Hexagonal               

Ø  No. of capsomeres in each ring – 6

Ø  No. of appendages attached to the tail – 12  

Ø  Approximate length of bacteriophage – 160 nm

Ø  Approximate length of bacteriophage DNA – 1,60, 000 nm = 0.16 mm

Sequence of changes takes place during  lytic cycle

Collision between the virions and the bacterial cells- The phages get attached to the surface of the host at specific sites - Secretion of lysozyme - Formation of a hole in bacterial cell wall due to the action of lysozyme - Injection of phage DNA in to the host cell - Degradation of host DNA - Synthesis of coat proteins - Replication of phage DNA- Synthesis of different components of capsid - Assemblage of components and formation of complete virions - Host cell wall ruptures due to the action of lysozyme and the virisons are released.

Scientist Name

Discovery

Alexander fleming Waksman Anton van leeuwenhoek Ehrenberg Louis Pasteur and Robert koch Earnest Haeckel Whittaker Christian Gram Frederick Griffith Lederberg and Tatum Lederberg and Zinder Heidi schulz Edward Jenner Louis Pasteur Andre Lwoff Iwanowski Beijerinck Stanley Pierie and Bawden Gierrer and Schramm Frankel and Conrat Franklin et al Twort Felix ‘d’ Herelle

Discovered pencillin from a fungus penicillium notatum Isolated an antibiotic from a bacterium Streptomyces griseus Discovered bacteria, coined the term “Animal cules”. Coined the term “Bacteria”. Discovered the pathogenic nature of Bacteria. Proposed three kingdom classification and placed bacteria under protista. Proposed five kingdom classification, placed bacteria under monera. Developed gram staining technique. Discovered bacterial transformation in Streptococcus pneumoniae. Discovered bacterial conjugation in E.coli Discovered transduction Salmonella typhimurium Discovered an ever largest bacterium Thiomargarita namibiensis Developed vaccine for small pox Developed vaccine for rabbies, coined the term virus, proposed germ theory of disease and established Pasteur research institute Said that A virus is a virus, former director of Pasteur research institute Discovered viruses. Discribed viruses as “contagium vivum fluidum”. Crystallized TMV. Chemical analysis of viruses. Discovered that the TMV is made up of nucleic acid and proteins. Proved the nature of nucleic acid as infections agent and genetic material Discovered that the genetic material in TMV is RNA Described the structure of TMV Discovered bacteria Coined the term bacteriophage

VIRAL DISEASES

Disease	Symptom	Examples
Chlorosis Mosaic Vein clearing Vein banding Ring spots Dwarfing/Stunting Malformation Breaking of flowers	Whitening or yellowing of entire leaf Loss of chlorophyll in isolated patches Loss of chlorophyll in the tissues close to veins Loss of chlorophyll in the lamina except in areas of veins Loss of chlorophyll in circular spots. Reduced growth. Abnormal growth Loss of colour at certain parts and formation of dark colour at certain parts	Peach yellowing disease Tobacco mosaic disease, Bean mosaic, Papaya mosaic , Cauliflower mosaic Bhendi vein clearing Citrus vein banding Tomato spotted wilt, cherry ring spot, papaya ring spot Rice stunting Swollen shoot of cocoa Tulip mosaic break

TRANSMISSION  OF  VIRUSES

Vector	Transmitted viruses
Vegetative parts Mechanical transmission Seeds (Post fertilized form of ovule) Pollen grains/Microspores (First cell of male gametophyte) Insects Nematodes(Xiphenima,Longidorus) Fungi(Olpidium brassicae) (Heterotrophic thallophyte) Phanerogamic parasites (Cuscuta) (Complete stem parasite)	Potato virus, Sugar cane virus, Banana virus Potato virus, TMV Bean mosaic, Lettuce mosaic Cherry ring spot virus Rice tungro, potato leaf roll, papaya mosaic Soil borne viral diseases TNV, soil borne viral diseases. Some viruses