文档介绍：Chapter 2 Cell Biology
Overview of the structure of microbial cells
Procaryotic cell wall
Cytoplasmic membrane
Cellular ic information
Cytoplasmic matrix – Ribosome and Inclusions
external to the cell wall
Bacterial endospores
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 peptidoglycan
The prokaryotic cell
1. Their ic material (DNA) is not enclosed within a membrane and they lack other membrane – anelles
2. Their DNA is not associated with histidine
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 8 x 50 um
parison of anisms
Visibility scale
Meters
Relative size of Microbes
Prokaryotes
Eukaryotes
Viruses
Naked eye
Light microscope
Electron microscope
a cell increases in size, its surface area – to – volume ratio decreases
Surface area and volume relationships in cells
spirallum
Shape: Bacteria have a few basic shapes
spherical us
Rod-shaped bacillus
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 (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