Chapter 4 - Bacteria and Archaea - 4.3 The Cell Envelope: The Boundary Layer of Bacteria - 4.3 Learning Outcomes-Assess Your Progress - Page 96: 8

The two main types of bacterial envelop structures are as follows: 1. Gram Positive: It has a thick petidoglycan layer in which teichoic acids are embedded. Many bacteria also have an S layer which consists of proteins. This layer helps bacteria to avoid being engulfed. 2. Gram Negative: It has a thin petidoglycan layer. It also has an additional membrane outside this layer for interaction with environment. Membranes called porins control in and out flow.

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