Microbial Cell Structure and Function Flashcards
Cocci
spheres
Diplococci
pairs of spheres
Streptococci
chains of spheres
Staphylococci
grape-like clusters of spheres
Tetrads
4 cocci in a square
Sarcinae
cubic configuration of 8 cocci
Bacilli
rods
Coccobacilli
very short rods
Vibrios
resemble rods, comma shaped
Spirilla
rigid helices
Spirochetes
flexible helices
Filamentous
- mycelium (mat)
- network of long, multicellular filaments
Pleomorphic
- variable in shape
- may not have cell wall so their shape can depend on what they are against
- default shape is round
Unique shapes
star
Unique arrangements
palisades (picket-fence)
What is the size range for eukaryotes?
0.8 micrometers-hundreds of mircometers
What is the size range for bacteria/archaea?
0.2 micrometers-750 micrometers
What is the size range for viruses?
0.01 micrometers-2.3 micrometers
How does surface to volume ratio change with size?
smaller organisms have a larger surface to volume ratio
Why is being small an advantage?
- large surface to volume ratio
- faster binary fission
- more room for diffusion
- get nutrients in and wastes out faster
- get mutations faster which leads to natural selection
What is the cytoplasmic membrane?
a thin structure that separates the cytoplasm from the environment
What are the major functions of the cytoplasmic membrane?
- permeability barrier
- site of many proteins: transport systems, bioenergetics, chemotaxis
- energy conservation: proton motive force
What is the cytoplasmic membrane composed of?
- lipid bilayer composed of amphipathic phospholipids (polar heads and nonpolar tails)
- phospholipids can be saturated or unsaturated depending on the environment
- have hopanoids to add structural stability
- have integral and peripheral proteins
What are the saturation levels reflected by?
- the environment
- cold environment: unsaturated (to increase membrane fluidity)
- warm environment: saturated (to decrease membrane fluidity)