Micro Exam 4
Organisms that exhibit mutualism Buchnera aphidicola and aphids
Gram-negative
617 kb genome (E. coli ~4.6 Mb)
Lives in the aphid (insect)
Buchnera aphidicola Inside aphid cells —>
bacteriocytes (mycetocyte)
Transmitted vertically from mother to
daughter
The two have evolved together for millions of
years
~75% of the Buchnera genome has been
What does the aphid do for Buchnera?
lost
Aphid provides Buchnera with amino
acids that Buchnera can’t make
“gnotobiotic” aphids (gnotobiotics = germ free)
Grow normally provided a diet
supplemented with amino acids
What does Buchnera do for the aphid?
Aphids cannot make Trp
Buchnera synthesizes & provides
Trp for the aphid
Mutualism is obligatory and the two organisms
need each other to survive
How is cooperation different from Mutualism? Cooperation results in both organisms
benefitting but they can each still survive
independently
Commensalism One organism benefits (the commensal) while
the other (host) isn’t harmed or helped
Staphylococcus epidermidis
Commonly found growing on skin
Organisms that exhibit mutualism Buchnera aphidicola and aphids
Gram-negative
617 kb genome (E. coli ~4.6 Mb)
Lives in the aphid (insect)
Buchnera aphidicola Inside aphid cells —>
bacteriocytes (mycetocyte)
Transmitted vertically from mother to
daughter
The two have evolved together for millions of
years
~75% of the Buchnera genome has been
What does the aphid do for Buchnera?
lost
Aphid provides Buchnera with amino
acids that Buchnera can’t make
“gnotobiotic” aphids (gnotobiotics = germ free)
Grow normally provided a diet
supplemented with amino acids
What does Buchnera do for the aphid?
Aphids cannot make Trp
Buchnera synthesizes & provides
Trp for the aphid
Mutualism is obligatory and the two organisms
need each other to survive
How is cooperation different from Mutualism? Cooperation results in both organisms
benefitting but they can each still survive
independently
Commensalism One organism benefits (the commensal) while
the other (host) isn’t harmed or helped
Staphylococcus epidermidis
Commonly found growing on skin
