Viruses Virus intracellular parasites small infectious agent that

Viruses

Virus “intracellular parasites” • small infectious agent that can replicate only inside the living cells of organisms

Chicken Pox and Shingles Virus

Virion: an entire virus particle • Consists of: • DNA or RNA • Protein Coat – called a capsid • Sometimes a lipid envelope around the protein coat • You Tube Lytic Cycle (2: 17)

Bacteriophage Virus • capsid

Sometimes glycoprotein spikes to help the virus enter and exit the host cell

LYTIC INFECTION • Animation of a Lytic Infection • Mc. Graw Hill Life Cycle of a T 2 Phage

HIV • The Human Immunodeficiency Virus (HIV) • Can lead to AIDS (acquired immunodeficiency syndrome)

HIV INFECTION • HIV infection: a retrovirus (high level) • Shows receptors and how anti-viral drugs can be effective HIV budding from a lymphocyte

Lytic Infection

Examples Lytic Infections • Common Cold • Influenza • Rabies • TMV (tobacco mosaic virus)

Lysogenic Infection

Temperate Viruses • Also called lysogenic viruses • are those that reproduce without killing their host cell.

Common Lysogenic Virus • • • Herpes (genital and cold sore) Papilloma HPV (cervical cancer) Retrovirus Hepatitis B Chicken Pox

Retroviruses • Retroviruses use RNA instead of DNA as their nucleic acid core. • also contain the enzyme reverse transcriptase

Retrovirus Examples • HIV • Rous sarcoma (first one discovered) • Leukemia viruses

Viroids • Viroids are naked • Infect plants circular RNA (no protein coat) molecules that are several hundred nucleotides long.

Viroid Attack on Potatoes • Used to make varieties in flowers

Prions • a form of a normal protein that is not folded correctly. • Cause degenerative brain disease

Mad Cow Disease • BSE = bovine spongiform encephalitis • It's. . . BSE You Tube • Can cause CJD in humans

CJD • Creutzfeldt-Jakob disease (CJD) is a form of brain damage that leads to a rapid decrease of mental function and movement. • You Tube The BSE Prion and Variant CJD

Vaccines • “Harmless” variants or derivatives of pathogenic microbes that stimulate the immune system to make antibodies against the pathogen.

Edward Jenner First Vaccine (for smallpox) • Gave cowpox to his son first • Lots of people were getting smallpox

BACTERIA • Prokaryotes • Most of its DNA is in a single chromosome

Bacteria Can Transfer DNA in 3 Ways • 1. Transformation – uptake of foreign DNA from the surrounding environment • 2. Transduction – transfer of bacterial genes by a bacteriophage • 3. Conjugation – physical union of two bacterial cells as they “mate”

Transformation

Transduction

Conjugation

Bacterial Plasmids • F Factor = fertility plasmid

F Plasmid • Resistance Plasmid • Carry genes to destroy antibiotics

Identifying Bacteria • Mc. Graw Hill Prokaryotic Cell Shapes

Can you name these shapes?

Can you name these shapes? • • A Bacilli with and without flagella B Streptococci C Staphylococci D Diplococci E Spirochete F Club rod G Filamentous H Streptobacilli

Spores • dormant, tough, and non-reproductive structure produced by certain bacteria