21 SEP SEP 12
How did scientists come up with the term VIRUS? In the 1890s, two scientists independently investigate the cause of the disease.
How did scientists come up with the term VIRUS? The scientists extracted sap from unhealthy leaves and put it on the leaves of normal, healthy plants
How did scientists come up with the term VIRUS? They filtered the sap to remove bacteria and then repeated the tests.
How did scientists come up with the term VIRUS? Their conclusion was that something smaller than bacteria were causing the disease.
Latin – Slime; poisonous liquid Modern – Agent that causes infectious disease
If viruses are smaller than bacteria, how big do you think they are? PREFIXSYMBOLFACTOR yottaY10 24 zettaZ10 21 exaE10 18 petaP10 15 teraT10 12 gigaG10 9 megaM10 6 kilok10 3 hectoh10 2 dekada10 1 decid10 -1 centic10 -2 millim10 -3 microµ10 -6 nanon10 -9 picop femtof attoa zeptoz yoctoy10 -24
What are the main components of a virus? Viruses are simple agents Capsid – Protein Shell Nucleic Acid Core Envelope – Outer Membrane Surface Receptors
PROTEINS Isoleucine Ile, I Asparagine, Asn, N Serine, Ser, S Proline, Pro, P Glutamic acid, Glu, E Threonine, Thr, T Amino Acids
Helical Viruses Tobacco Mosaic Virus
Polyhedral Viruses Adenovirus
Complex Viruses Bacteriophages T4
Capsid Head Tail sheath DNA T4 Bacteriophage Tobacco Mosaic Virus Influenza Virus RNA Tail fiber RNA Capsid proteins Surface proteins
DNA Deoxyribonucleic acid Adenine Guanine Thymine Cytosine
RNA Ribonucleic acid Adenine Guanine Uracil Cytosine
Viruses genomes can be either double stranded or single stranded.
Viruses can only have one type of nucleic acid. It must be DNA or RNA, not both!
Helps get the virus into the host cell.
Acquired from the host cell.
Is sensitive and can be disrupted by desiccation, heat, and exposure to detergents.
Help the virus recognize the host cell.
Are very specific – have a key and lock relationship.
Protein Shell DNA or RNA Membrane around virus Proteins that help virus get into proper host