文档介绍：A anization
A1 Prokaryotes
A2 Eukaryotes
A3 Microscopy
A4 Cellular fractionation
A1 Prokaryotes
Prokaryotes
Cell structure
Bacterial cell walls
Prokaryotes
Prokaryotes are the most anisms on earth. (bacteria and blue-green algae)
A prokaryotic cell dose not contain a membrane-bound nucleus.
Size from to 10 μm
Three basic shapes
Spherical(i:球菌)
Rodlike(bacilli:细菌,杆菌)
Helically coiled( spirilla:螺旋菌)
They fall into two groups:the eubacteria 真细菌and the archaebacteria(古细菌).
the eubacteria(真细菌)
Gram-positive
Gram-negative
Cyanobacteria (cyano深蓝色的-bacteria)
in soil,water and living in or on anisms
the archaebacteria(古细菌)
Sulfur硫 bacteria
Methanogens(methane-甲烷)
They grow in unusual environments:
salt brines,hot acid springs,in the ocean depths
Cell structure
Each prokaryotic cell is surrounded by a plasma membrane质膜.
The cell has no anelles,only infoldings of the plasma membrane called mesosomes中间体.
The deoxyribonucleic aid (DNA) is condensed within the cytosol to form the nucleoid拟核.
Some prokaryotes have tall-like flagella鞭毛.
Cell structure
Bacterial cell walls
The peptidoglycan (protein and a-ride) cell wall protects the prokaryotic cell from mechanical and osmotic pressure.
A Gram-positive bacterium has a thick cell wall surrounding the plasma membrane,whereas Gram-negative bacteria have a thinner cell wall and outer membrane,between which is the periplasmic space.
Gram negative cell walls