华中农业大学微生物学第二章.pptVIP

Chapter 2 Cell Biology Concepts Prokaryotes are small and simple in structure when compared with eukaryotes , yet they often have characteristic shape and size. Prokaryotic genetic material is located in an area called the nucleoid and is not enclosed by a membrane. The prokaryotic cell wall almost always has peptidoglycan and is chemically and morphologically complex. 3. Their cell wall almost always contain the complex polysaccharide peptidoglycan The cell wall of the bacterial cell is a complex, semi-rigid structure that is responsible for the characteristic shape of the cell. The cell wall surrounds the underlying, fragile plasma (cytoplasmic) membrane and protects it and internal parts of the cell from adverse changes in the surrounding environment. Almost all prokaryotes have cell walls. Structure of cytoplasmic membrane Bacterial Chromosome Supercoiling and chromosome structure Chromosomal copy number 2. Plasmids The major function of S-layers is unknown. As the interface between the cell and its environment ,it is likely that in cells that produce them the S-layer at least functions as an external permeability barrier, allowing the passage of low-molecular-weight substances while excluding large molecules. 4.What are the major morphologies of prokaryotes? Draw cells for each morphology you list. 5. The discovery of the bacterial endospore was of great practical importance. Why? 6. How does the eukaryotic nucleus differ from the prokaryotic nucleoid? In what ways are these two structures similar? 2. From what you know about the nature of the bacterial cell will and membrane, explain why a rod-shaped bacterial cell becomes a spherical structure when its wall is removed under conditions such that cell lysis cannot occur.? 3. Assume you are given two cultures, one of a species of gram-negative Bacteria and one of a species of Archaea. Other than by sequencing ribosomal RNA, discuss at least five different ways you could te