pre31_part2

pre31_part2 - Class 31, second half THIS BEGINS UNIT 5...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Class 31, second half Biol 002 4/14/08 THIS BEGINS UNIT 5 Reading: Chapter 27: 554-556 Topic: Human symbioses I. Our "commensal" load has aspects of mutualism and parasitism Think of examples of both consider the mouth (554) parasitism: dental caries (tooth decay) and the large intestine (557) Mutualism: large colonies of bacteria that produce B12 and K vitamins that humans cannot produce alone. Dental plaque: example of bacterial biofilms Dental caries: sucrose causes tooth decay in two ways 1. Sugar is fermented into lactic acid that reduces the pH of the mouth, loses calcium 2. If sucrose continues to be present, the pH of the mouth is always low and the enamel of teeth is broken down further. Soft matrix of teeth is vulnerable to bacterial attack How is bacterial metabolism involved? Bacterial cells surrounded by polysaccharide matrix; filaments of rod- shaped cells that project out perpendicular to the tooth surface; many different bacteria are involved. II. Disease mechanisms
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 2

pre31_part2 - Class 31, second half THIS BEGINS UNIT 5...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online