Viruses • Viruses are nucleic acids (DNA/RNA) wrapped in protein • Typically the protein coat, or capsid, of an individual virus particle, or virion, is composed of multiple copies of one or several types of protein subunits, or capsomeres. Some viruses contain enzymes, and some have an outer membranous envelope. Many viruses have striking geometrically regular shapes
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Viruses• Viruses are nucleic acids
(DNA/RNA) wrapped in protein
• Typically the protein coat, or capsid, of an individual virus particle, or virion, is composed of multiple copies of one or several types of protein subunits, or capsomeres. Some viruses contain enzymes, and some have an outer membranous envelope. Many viruses have striking geometrically regular shapes
Virus Shapes3 main shapes:• Icosohedron/polyhedron: 20 triangular
sections (HIV)• Spiral: RNA surrounded by capsomere
host cells that they infect to reproduce. When found outside of host cells, viruses exist as a protein coat or capsid, sometimes enclosed within a membrane. The capsid encloses either DNA or RNA which codes for the virus elements.
Helpful Viruses• Viruses carry out natural "genetic
engineering": by incorporating genetic material into its host
• This is known as transduction, and in some cases it may serve as a means of evolutionary change
• Certain varieties of flowers have been developed using viruses to alter the genetic code.
• Dr Patrick Lee uses reovirus to kill brain cancer cells transplanted into laboratory mice, while sparing normal, healthy cells. Clinical trials involving reovirus in people are now underway.
• Virus Rap
Helpful Viruses• A good virus• Most of us go out of our way to avoid viruses. But
Dr Patrick Lee - formerly of the University of Calgary and now at Dalhousie University - spends a lot of time in the company of a very common virus known as a reovirus. Normally this bug causes nothing more serious than a mild infection. But Dr Lee’s team discovered that the reovirus has the ability to kill brain cancer cells transplanted into laboratory mice, while sparing normal, healthy cells. Clinical trials involving reovirus in people are now underway.
How do they get in?• Lambda phage Replication
• Replication of a Positive (+) Sense Strand of Lytic RNA Phage
• T4 Replication• Entry into Animal Cell • Release of Enveloped Viruses• Replication of Retrovirus• Influenza
Essential knowledge 3.C.3: Viral replication results in genetic variation, and viral infection can introduce
genetic variation into the hosts.
b. The reproductive cycles of viruses facilitate transfer of genetic information.1. Viruses transmit DNA or RNA when they infect a host cell.
• Transduction in bacteria (Specialized Transduction)• Transposons present in incoming DNA
2. Some viruses are able to integrate into the host DNA and establish a latent (lysogenic) infection. These latent viral genomes can result in new properties for the host such as increased pathogenicity in bacteria.
LO 3.29 The student is able to construct an explanation of how viruses introduce genetic variation in host organisms.
Lysogenic Cycle• When it comes into contact
with a host cell, a virus can insert its genetic material into its host, literally taking over the host's functions. An infected cell produces more viral protein and genetic material instead of its usual products. Some viruses may remain dormant inside host cells for long periods, causing no obvious change in their host cells (a stage known as the lysogenic phase).
Lytic Cycle• when a dormant virus is
stimulated, it enters the lytic phase: new viruses are formed, self-assemble, and burst out of the host cell, killing the cell and going on to infect other cells
Essential knowledge 3.C.3: Viral replication results in genetic variation, and viral infection can introduce
genetic variation into the hosts.
a. Viral replication differs from other reproductive strategies and generates genetic variation via various mechanisms.
1. Viruses have highly efficient replicative capabilities that allow for rapid evolution and acquisition of new phenotypes. Viral Recombination , 1918 Spanish Flu, 2, 3
2. Viruses replicate via a component assembly model allowing one virus to produce many progeny simultaneously via the lytic cycle.
3. Virus replication allows for mutations to occur through usual host pathways.4. RNA viruses lack replication error-checking mechanisms, and thus have higher rates
of mutation.5. Related viruses can combine/recombine information if they infect the same host cell. (
Antigenic Shift)6. HIV is a well-studied system where the rapid evolution of a virus within the host
contributes to the pathogenicity of viral infection.
LO 3.30 The student is able to use representations and appropriate models to describe how viral replication introduces genetic variation in the viral population.
Life Cycle of HIV HIV Life Cycle 2 HIV Replication Future of HIV
BB CheckpointBB#1SB1a. Explain the role of cell organelles for both prokaryotic and eukaryotic cells, including the cell membrane, in maintaining homeostasis and cell reproduction.
BB#8 SB2e. Compare the advantages of sexual reproduction and asexual reproduction in different situations
BB#10 SB3b. Compare how structures and function vary between the six groups (archaebacteria, eubacteria, protists, fungi, plants, and animals).
Kingdom Protista• All protists are eukaryotes.
This means that their cells contain a nucleus, a membrane-bounded structure that encloses the
cell's genetic material. • Some protists are
autotrophs like plants, others are consumers like animals. Unlike plants and animals, however, protists do not have cells organized into specialized tissues.
Protista Classified by Nutrition• The first detailed descriptions of
protists were made in 1676 by the inventor of the microscope, Dutch naturalist Leewenhoek.
• The classification is currently based on the structure and organization of the cell, the presence of organelles, and the pattern of reproduction or life cycles. The five-kingdom system divides the Protista into 27 phyla. However, classifications based on DNA sequences suggest that many protist phyla may be sufficiently large and diverse to be classified as kingdoms.
• Gallimaufry, cornucopia, hodge-podge, potpourri
• Auto trophic Protists are called “Algae”. Scientists believe they gave rise to the kingdome Plantae
• Ingestive Heterotrophic protists are called “Proto zoa”. Scientists believe they gave rise to the kingdom Animalia
• Absorptive heterotrophic protists are called “Slimemolds”. Scientists believe they gave rise to the kingdom Fungi
Bacteria Links•Bioterrorism: •Bacterial Cell Walls: •10 Ways a World Will End: Monster Plague•Discovery of the Germ Theory•Antibiotics Tutorial •Anti-antibiotics/Efflux Pump•Immunology Primer •When Worlds Collide, Macro vs. Micro •Immuno- biology Animations
Fungi Links•Fungi Chapter 30•Tom Volk’s Fungi
Virus LinksVirus Pictures:
Virus Review:
Exploring Life:
Big Picture Book of Viruses:
AIDS Online:
Replication of Herpes Animation:
Influenza Entry Animation:
Antigenic Shift Animation
Immuno- biology Animations
Chapter 6 Viruses
Introduction to Plasmids & Viruses
Bozeman Viral ReplicationSuper Flu: Antigenic shift in influenza