Chapter 2 Cell biology.ppt

Chapter 2 Cell Biology
Overview of the structure of microbial cells
Procaryotic (原核生物的) cell wall
Cytoplasmic(细胞质的)membrane
Cellular ic information
Cytoplasmic matrix(基质) – Ribosome(核糖体) and Inclusions(内含物)
external to the cell wall(细胞壁的外部组分)
Bacterial endospores(内生孢子or芽孢)
of the prokaryotic and eukaryotic cell
Chapter outline
A procaryotic cell
A eucaryotic cell
Overview of cell structure
3. Their cell wall almost always contain plex haride(多糖)— peptidoglycan(肽聚糖)
The prokaryotic cell
1. Their ic material (DNA) is not enclosed within a membrane and they lack other membrane – anelles(细胞器)
2. Their DNA is not associated with histidine(组氨酸)
4. They are very small!!
Size: Most bacteria fall within a range from to um in diameter and from 2 to 8 um in length
A rod-shaped prokaryote is typically about 1-5 micrometers (μm) long and about 1 μm wide
anisms in general are very small and pletely invisible to the naked eye.
A cyanobacterium(藻氰菌) 8 x50 um
parison of anisms
Visibility scale
Meters
Relative size of Microbes
Prokaryotes
Eukaryotes
Viruses
Naked eye
Light microscope
Electron microscope
Spirallum(螺菌)
Shape: Bacteria have a few basic shapes
spherical us(球菌)
rod-shaped bacillus(杆菌)
The cell wall of the bacterial cell is plex, semi-rigid structure that is responsible for the characteristic shape of the cell. The cell wall surrounds the underlying, fragile plasma(细胞质) (cytoplasmic) membrane and protects it and internal parts of the cell from adverse changes in the surrounding environment.
Almost all prokaryotes have cell walls.
Prokaryotic cell wall
Gram+
Gram-
Schematic diagram of bacterial cell walls
Bacteria can be divided into two major groups, called gram-positive and gram-negative. The original distinction between gram-positive and gram-negative was based on a special staining procedure, the Gram stain
The Gram-positive cell wall has a peptidoglycan(肽聚糖) layer that