Virology Unit 1

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tapper1808
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132709
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Virology Unit 1
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2012-03-02 21:46:15
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Virology Biology Viruses
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Biology of Viruses, Virology Chapter 1, 2
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  1. Porin
    A transmembrane protein of a cell that serves as a tranport channel for ions and other small nutrient molecules.
  2. LPS
    • Lipopolysaccharide
    • Play a major role in viral/ bacterial cell interactions.
    • Fount on Gram-negative bacteria.
    • A common binding site on E. Coli for the T4 bacteriophage.
    • Part 1: Lipid A anchors LPS to the outer membrane.
    • Part 2: The core, is a long chain of sugars.
    • Part 3: The O antigen, a repeating set of sugars (probably used for reconition by virus).
  3. T4
    • Bacteriophage infecting E. Coli
    • Icosohedral head
    • Helical tail
    • Baseplate
    • Six spikes and tail fibers
    • Reversible and irriversible attachment components
  4. Plasmid
    A circular form of DNA that replicate independently from the chromosome. They are not essential but may give the bacteria a selective advantage such as antibiotic proteins that can kill other bacteria.
  5. λ
    • Bacteriophage of E. Coli
    • Icosahedral head and helical tail
    • Single tail fiber (no baseplate)
    • binds to lamB protein present when maltose is available
  6. Pilot protein
    Protein bound to the end of viral DNA that assists in it's transfer and initiation of replication within the bacterial host cell.
  7. Picornaviruses
    • Pico(small)rna(RNA)virus;
    • Naked icosahedron
    • Baltimore class IV
    • Enter by endocytosis

    • enteroviruses (polioviruses)
    • echoviruses (enteric, cytopathic, human, orphan{not assoc. w/ disease})
    • rhinovirus ( rhino=nose, cold viruses)
  8. Monoclonal antibody
    A single antibody producing cell is cloned (made to proliferate) in vitro.
  9. Glycoprotein
    A molecule that consists of a carbohydrate plus a protein. Glycoproteins play essential roles in the body. For instance, in the immune system almost all of the key molecules involved in the immune response are glycoproteins. A glycopeptide is similar in structure to a glycoprotein but has a shorter chain of amino acids.
  10. Carbohydrates (saccharides)
    Molecules consist of carbon, hydrogen and oxygen atoms. A major food source and a key form of energy for most organisms. When combined together to form polymers, carbohydrates can function as long term food storage molecules, as protective membranes for organisms and cells, and as the main structural support for plants and constituents of many cells and their contents.
  11. Lipids (fats)
    Molecules consist of carbon, hydrogen, and oxygen atoms. The main constituents of all membranes in all cells (cell walls), food storage molecules, intermediaries in signaling pathways, Vitamins A, D, E and K, cholesterol.
  12. Proteins
    Molecules contain nitrogen, carbon, hydrogen and oxygen. They act as biological catalysts (enzymes), form structural parts of organisms, participate in cell signal and recognition factors, and act as molecules of immunity. Proteins can also be a source of fuel.
  13. Nucleic acids
    DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). These molecules are involved in genetic information, as well as forming structure within cells. They are involved in the storage of all heritable information of all organisms, as well as the conversion of this data into proteins.
  14. What are saccharides?
    Saccharides, or carbohydrates, are sugars or starches. Saccharides consist of two basic compounds:Aldehydes - composed of double-bonded carbon and oxygen atoms, plus a hydrogen atom. Keytones - composed of double-bonded carbon and oxygen atoms, plus two additional carbon atoms.There are various types of saccharides:Monosaccharide - this is the smallest possible sugar unit. Examples include glucose, galactose or fructose. When we talk about blood sugar we are referring to glucose in the blood; glucose is a major source of energy for a cell. In human nutrition, galactose can be found most readily in milk and dairy products, while fructose is found mostly in vegetables and fruit.
  15. Maltose
    A white crystalline sugar, C12H22O11, formed during the digestion of starch.
  16. SU
    The HIV envelope glycprotein
  17. CD4
    The receptor for HIV, an enveloped virus, which is located on the surface of helper T lymphocytes
  18. TM
    transmembrane glycoprotein holds SU in place
  19. Virus (General)
    • Latin for "poinson"
    • Causative agent for numerous diseases.
    • Small and cannot be seen under a light miscroscope and can pass thru flters.
    • Cannot be cultivated on artificial media, must be in a living host cell - intracellular parasites.
  20. Virus
    • Contains a single type of nucleic acid - either DNA or RNA
    • The remainder is protein or glycoprotein (no lipids, glycolipids, simple sugars, polysaccharides, nucleotides (ATP & ADP), free amino acids or other small molecules.
  21. Telomere
    A region of repetitive nucleotide sequences at the end of a chromosome, which protects the end of the chromosome from deterioration or from fusion with neighboring chromosomes.
  22. Nucleocapsid
    Viral structure, consisting of a capsid with the enclosed nucleic acid.
  23. Capsid
    Protein shell of a virus.
  24. Capsomer
    • The morphological units of the capsid.
    • Formed of a definite number of individual proteins (structural subunits or protomers).
  25. Icosahedron
    • "Sphereical" shaped nucleocapsid.
    • 3-D structure wth 20 faces in the shape of equilateral triangles.
    • Forms "head"
  26. Tail
    • Helical arrangement of proteins attached to the head.
    • May contain various spikes and fibers used for attachement.
  27. Envelope
    • Membrane derived from host cell.
    • Presence means that the virus particle contains lipids in addition to prteins and nucleic acids.
    • Enveloped viruses may have either helical or icosahedral nucleocapsids.
    • Frequently contain spikes.
    • Ether-sensitive: can be destroyed by organic solvents like ether.
  28. Spikes
    • Projections
    • Virus specific proteins inserted into the basic membrane system of the host cell.
  29. Naked virus
    • Non-enveloped
    • Not affected by organic solvents, don't interact with nonpolar solvents.
    • Contain no lipids.
    • Protein nucleocapsids are hydrophilic.
  30. Fluid-mosaic membrane model
    Phospholipid bi-layer arranged with hydrophobic fatty acid tail towards center and hydrophilic phosphate and other charged groups facing outer and inner surfaces.
  31. Integral proteins
    • Go thru the entire membrane and can serve as pores.
    • Intrinsic proteins.
  32. Peripheral proteins
    • Embedded in only one side of the cell membrane.
    • Extrinsic proteins.
  33. Gram-positive cell wall
    • In prokaryotic cells, a thick surrounding layer.
    • Composed of peptidoglycan, cross linked chains of amino acids and sugars.
    • Does not allow viruses to identify specific species of bacteria since this basic architecture is shared by all Gram-positive bacteria.
  34. Gram-negative cell wall
    • Thin peptidoglycan layer (usually 1 or 2 layers thick).
    • Fewer amino-acid chains involved in cross-linking the glycan chains.
    • Have phospholipid bilayer outer membrane containing prteins sililar to plasma membranes.
    • Outer membrane contains lipopolysaccharides (LPS)
  35. Flagella
    • Appendage on a bacterium that is hollow and whiplike.
    • Used for locomotion.
    • Composed of protein, flagellin, arranged in a hexagonal pattern.
    • Attachment site for some viruses.
  36. Pilus
    • Very fine hairlike tubule.
    • Attachment site for some viruses.
  37. Central Dogma of Molecular Biology
    • DNA is replicated to make more.
    • DNA is transcribed to make mRNA.
    • mRNA is translated to make proteins.
  38. Prokaryotic Cell
    • 1DNA molecule
    • Circular DNA
    • Haploid
    • Operons
    • Polycistronic mRNA's
    • No postranscritional modifications
    • No compartmentalization
    • Continuous life cycle
  39. Operon
    A functioning unit of genomic DNA containing a cluster of genes under the control of a single regulatory signal or promoter. The genes are transcribed together into an mRNA strand and translated together in the cytoplasm.
  40. Euykaryotic cell
    • >1 DNa molecule
    • Linear DNA
    • Diploid
    • No operons
    • Monocistronic mRNA's
    • Cappoing, tailing, and splicing of transcript
    • Compartmentalization
    • May exit cycle to G0
  41. Polycistronic
    • mRNA carries genetic information to translate several protein chains (polypeptides).
    • These polypeptides usually have a related function (they often are the subunits composing a final complex protein) and their coding sequence is grouped and regulated together in a regulatory region, containing a promoterand an operon.
    • No 5' cap or 3' tail
  42. Plasmid
    • A DNA molecule that is separate from, and can replicate independently of, the chromosomal DNA.
    • They are double-stranded and, in many cases, circular. Plasmids usually occur naturally in bacteria.
  43. Steps of viral replication
    • 1. Attachement
    • 2. Penetration and uncoating
    • 3. Synthesis of viral proteins and nucleic acids
    • 4. Synthesis of viral structural proteins
    • 5. Maturation
    • 6. Release
  44. Baltimore classification
    Viral classfication based upon relationship between the viral genome and the mRNA.

    • Positive mRNA can be used to synthesize proteins
    • Negative mRNA are the compliment to positive mRNA
  45. Class I virus
    • ds-DNA
    • mRNA synthesized in the normal fashion using the negative strand DNA as the template.
    • mRNA created in the 3' to 5' direction.
  46. Class II virus
    ss-DNA

    • IIA= +
    • IIB= -

    Both create a double stranded DNA intermediate to creating mRNA.
  47. Class III virus
    • ds-RNA
    • One strand equivalent to mRNA.
  48. Class IV virus
    • ss-RNA
    • Positve and can serve as mRNA.
  49. Class V virus
    • ss-RNA
    • Negative and cannot serve as mRNA.
    • It is a template for mRNAsynthesis.
  50. Class VI virus
    • ss-RNA
    • Positive strand but expression and replication require synthesis of a double stranded DNA molecule.
    • Retroviruses.
  51. Host ranges
    Types of different cells or organisms a virus can infect.
  52. Paramyxoviruses
    • Enveloped helix viruses
    • Use carbohydrates as host recognition molecules
    • Paramyxoviruses: beside + mucus
    • (were included in orthomyxo group until differences were found)
    • Mumps
    • Morbillivirus (Measels)
  53. Orthomyxoviruses
    • Enveloped helix viruses
    • Use carbohydrates as host recognition molecules
    • Orthomyxoviruses: straight + mucus
    • Influenza A
  54. What mediates binding?
    • Electrostatic interactions
    • Correct 3-d shapes to fit together
    • Correct ionization
  55. OmpC
    Porin on E. Coli that T4 bacteriophages use to recognize and bind.
  56. Penetration
    Viral nucleic acid moves from the virion to the host cell.
  57. Uncoating
    If necessary
  58. Coliphage
    Virus that infects E. Coli
  59. Pilot protein
    Attached to the end of T4 viral DNA to provide assistance in transferring it thru the tube and initiating DNA replication.
  60. Canyon
    • Area where capsomeres of rhinovirus and some other picornaviruses meet at a vertex causing a depression.
    • It allow it to bind to ICAM-1 receptor site on cells.
  61. Spike
    Long slender fiber with a knob at its end that is attached to12 vertices of its capsid.
  62. Hemagglutination
    Causing erythrocytes to clump together.
  63. Erythrocyte
    • A cell that contains hemoglobin and can carry oxygen to the body.
    • Also called a red blood cell (RBC).
    • Do not carry out ant of the processes of the Central Dogma and are incapable of supporting viral replication.
  64. Enveloped virus
    • Membrane surrounding capsid.
    • Usually derived from host cell membranes.
    • Contain proteins and glycoproteins as well.
    • Binding proteins often form projections or spikes.
  65. Rhabdovirus
    Bullet shaped; envelope surrounds helical nucleocapsid wrapped into a spiral that tapers at one end.
  66. Clathrin-coated pits
    • Funciton in endocytosis and are vesicles that have a crystalline coat made up of the protein clathrin.
    • Are found in virtually all cells and form domains of the plasma membrane termed clathrin-coated pits.
    • They can endocytose large extracellular molecules.
    • Used by Adenoviridae viruses to enter cells.
  67. Adenoviridae
    • Naked icosahedron
    • Spiked
    • enters thru clathrin-coated pit
    • Baltimore class I

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