Chapter 27 (2)

Chapter 27 (2) - Chapter 27 Chapter 27 Prokaryotes...

Info iconThis preview shows pages 1–11. Sign up to view the full content.

View Full Document Right Arrow Icon

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

View Full DocumentRight Arrow Icon

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

View Full DocumentRight Arrow Icon

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

View Full DocumentRight Arrow Icon

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

View Full DocumentRight Arrow Icon

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

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

Unformatted text preview: Chapter 27 Chapter 27 Prokaryotes Overview: They’re (Almost) Everywhere! Most are microscopic – What they lack in size they make up for in #’s # of prokaryotes in single handful of fertile soil – Greater than # of people who have ever lived Thrive almost everywhere – Places too acidic, too salty, too cold, or too hot for most other organisms Figure 27.1 Concept 27.1: Structural, functional, and genetic adaptations contribute to prokaryotic success Most prokaryotes are unicellular – Some species form colonies Variety of shapes – 3 most common are spheres (cocci), rods (bacilli), & spirals 1 μ m 2 μ m 5 μ m (a) Spherical (cocci) (b) Rod-shaped (bacilli) (c) Spiral Figure 27.2a–c Cell-Surface Structures Cell-Surface Structures One of most impt. features of nearly all prokaryotic cells – Cell wall (maintains cell shape, physical protection, prevents cell from bursting in hypotonic environment) Using technique called Gram stain – 2 groups based on cell wall composition, Gram- positive & Gram-negative (a) Gram-positive. Gram-positive bacteria have a cell wall with a large amount of peptidoglycan that traps the violet dye in the cytoplasm. The alcohol rinse does not remove the violet dye, which masks the added red dye. (b) Gram-negative. Gram-negative bacteria have less peptidoglycan, and it is located in a layer between the plasma membrane and an outer membrane. The violet dye is easily rinsed from the cytoplasm, and the cell appears pink or red after the red dye is added. Figure 27.3a, b Peptidoglycan layer Cell wall Plasma membrane Protein Gram- positive bacteria 20 μ m Outer membrane Peptidoglycan layer Plasma membrane Cell wall Lipopolysaccharide Protein Gram- negative bacteria Some have fimbriae & pili – Allow them to stick to substrate or other individuals in a colony 200 nm Fimbriae Figure 27.5 Motility Motility Most propel by flagella – Structurally & functionally different from eukaryotic flagella Flagellum Filament Hook Cell wall Plasma membrane Basal apparatus 50 nm Figure 27.6 In a heterogeneous environment, many...
View Full Document

This note was uploaded on 01/18/2011 for the course BIO 103 taught by Professor Sanders during the Spring '10 term at Northwestern IA.

Page1 / 46

Chapter 27 (2) - Chapter 27 Chapter 27 Prokaryotes...

This preview shows document pages 1 - 11. Sign up to view the full document.

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