Lecture 5: Bacterial taxonomy (cont.) Flashcards
Describe the general structure of a hyphomicrobium (visualize it) and how its structure relates to its lifestyle.
It consists of cells containing the cytoplasm and genome that are connected by a hypha. They use the hypha to stick to surfaces and sense whether it has enough nutrients to grow. Once it is ready to live elsewhere, it can detach the hypha and find a new habitat.
Name and visualize the 6 main bacterial colony forms.
Punctiform, circular, filamentous, irregular, rhizoid, spindle
Name and visualize the 5 main bacterial colony elevation types.
Flat, raised, convex, pulvinate, umbonate
Name and visualize the 6 main bacterial colony margin types.
Entire, undulate, lobate, erose, filamentous, curled
How do bacterial cells differ from human cells in terms of: diameter, surface area, volume, surface/volume ratio
Diameter: prokaryotes 10X smaller
Surface area: prokaryotes 405X less
Volume: 8057X smaller
Surface/volume ratio: 20X larger
Why are bacterial cells so much smaller than eukaryotic cells?
Because the goal of bacteria is to grow as fast as possible, so they need to be small and have a limited genome to be able to divide quickly.
Explain why the surface/area volume ratio in bacterial cells is so much larger than in eukaryotic cells.
In bacterial cells, nutrients enter via diffusion. At a higher surface area/volume ratio, the nutrients can access the cell in much greater numbers and more quickly, allowing faster growth.
Describe the structure of Thiomargarita namibiensis and its function.
Most of the cell is occupied by a large nitrate vacuole, which is used by the cells to grow. In the vacuole are circles made of sulfur. Its cytoplasm outlines the cell and is right up against the cell membrane. This is so that nutrients go directly into the cytoplasm after being uptaken.
What is the diameter of a bacterial cell vs the diameter of a human cell?
1 micrometer vs 10 micrometers
What is the surface area of a bacterial cell vs the surface area of a human cell?
3.1 um2 vs 1257 um2
What is the volume of a bacterial cell vs the volume of a human cell?
0.52 um3 vs 4190 um3
What is the surface area:volume of a bacterial cell vs the surface area:volume of a human cell?
6 vs 0.3
Give 3 examples of bacteria that are exceptions to the typical size of bacteria in that they are much larger.
Epulopiscium fishelsoni (gram +), thiomargarita namibiensis (gram -), and Thiomargarita magnifica (gram -)
What does the name epulopiscium fishelsoni mean?
It means “guest at a fish’s banquet”, as it is found in the gut of a brown surgeon fish.
How does the size of epulopiscium fishelsoni compare to E.Coli?
It is 1 million times larger than E. Coli
