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 McGraw Hill Life Cycle of a T2 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 circular RNA (no protein coat) molecules that are several hundred nucleotides long. Infect plants

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 McGraw 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