Biology 151 CHOLERA AND ECOLI Very basic concept of evolution 1 All species are related by common ancestry 2 Species evolve because of natural selection for variable heritable traits 3 Selection is when a trait leads to reproductive advantage the trait s fitness 4 Individual s do not adapt species evolve Cholera is able to survive in water When not in water it forms associations with copepods eggs and other organisms and aquatic environments Water will move in or out of the cell based on the molecules dissolved on each side of the membrane OSMOSIS 1 Membranes are permeable to water but not ions 2 So water goes into the cell if there s more solute in there 3 Water goes out if there s solute in intestine Cholera is caused by bacteria that attack the lining of the colon Onset of the disease is extremely fast so there isn t always adequate time to obtain treatment Death can occur in one or two days The second is that the disease frequently occurs after flooding or other natural disasters in impoverished areas This means that medication antibiotics clinics doctors are frequently not available or accessible What makes the disease so deadly is the severe dehydration it causes once symptoms begin to set in Water leaves cells due to osmosis The intestine then fills with water Treated with immediate rehydration Electrolytes and sugar and salt with 1 liter of water