Transcript Bacteria
Human Health and Disease Bacteria and Viruses Bacteria: Characteristics: •Prokaryotic •Kingdom Monera •Single-celled organism with no membrane-bound organelles •Reproduce asexually •Components: Cell wall, Cell membrane, cytosol, ribosomes and DNA plasmids. Some have cilia or flagella for movement Types of bacteria Gram-positive Bacteria Possess a thick peptide layer which retains a stain called crystal violet. Appear purple when viewed under a microscope. Gram-negative Bacteria • have a thin peptide layer, take up the pink stain, and appear pink when viewed under a microscope. Shapes of bacteria: Bacillus (rod-shaped), Cocci (round), Spirillum (corkscrew-shaped) Bacillus: Example: Anthrax ispub.com nanopatentsandinnovations.blogspot.com Cocci: Example: streptococcus (causes strep throat) medschool.lsuhsc.edu hardinmd.lib.uiowa.edu Spirillum/Spirochetes: Example: Treponema pallidum- causes syphilis www2a.cdc.gov www2a.cdc.gov www.kellykite.com How Bacteria Cause Disease • Metabolizing the host– Heterotrophic bacteria obtain nutrients by secreting enzymes that break down organic structures and absorb them – If the environment is your throat or lungs, this can cause serious problems! • Ex. – Tuberculosis bacteria settle into the lungs and use human tissue as their nutrients – Propionibacterium acnes causes acne • ToxinsSome bacteria secrete chemical compounds into their environment which are poisonous to eukaryotic cells (toxic) – Ex. Diptheria grows in the throat, but the toxins attack the heart, nerve, liver and kidneys – Food poisoning occurs when humans eat food where bacteria have grown and produced toxins What can you do? • Protect your food: – Heat – Freeze – Dry Evolution of Antibiotic Resistance: • Forty or fifty years ago, thanks to antibiotics, scientists thought medicine had all but eradicated infectious agents as a major health threat. • More recently, an upsurge of infectious disease is a problem we have unwittingly created for ourselves b/c: – rapid, frequent, and relatively cheap international travel allows diseases to leap from continent to continent – Many people have inadequate sanitation and lack of clean drinking water – We have overused the "miracle drugs“ to treat such diseases to the point that they lose their potency • Whenever antibiotics wage war on microorganisms, a few of the enemy are able to survive the drug. • Because microbes are always mutating, some random mutation eventually will protect against the drug. • Antibiotics used only when needed and as directed usually overwhelm the bugs. • Too much antibiotic use selects for more resistant mutants. • When patients cut short the full course of drugs, the resistant strains have a chance to multiply and spread.