BIOL 1002 : Exam 2 Info
Document Summary
Chapter 19: microbes can be found in all three domains of life. Being a microbe doesn"t allow you to classify it into a domain. Prions developed as a by-product of living organisms. You might as well ask the origin of living organisms. Prokaryotes: bacteria & archaea domains, 12000 species described, may be 100-1000x that number, 1st organism to appear on earth at least 3. 5 billion years ago. The ones that make us sick e-coli. They are semi-rigid/flexible, permeable, made of peptidoglycan (carbohydrate with amino acids attached polysaccharide) gives bacteria shapes. Shapes: bacilli rod, cocci spherical, spirilla spiral. Most bacteria fall into gram-positive or gram-negative categories after being tested in a stain. Gram-positive has two structures: plasma membrane & peptidoglycan, surrounding it. A gram-negative has 3 layers, (plasma membrane + peptidoglycan layer is thin + outer membrane) loses dye that is easily rinses away. If they were endospores humans would be in trouble.
