aa motif / Coiled-coils

3.6 a.a / turn in helix 

abcdefg 'a' &'d’ are hydrophobic residues 'e' and 'g' are found to be charged amino 

7.2 a.a / 2 turns acids 

 —7 amino acids per 2 turns in the helix 

For every turn there could be one hydrophobic residue coming same side of the helix 

Ex: GCN4

TLS Online TPP Program

#Id: 5737

#Unit 10. Ecological Principles

Five Hypotheses Explain How Species Richness Affects Community Services Diversity-stability hypothesis, more species are present, the more stable the community.

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#Id: 5738

#Unit 10. Ecological Principles

Elton’s hypothesis suggests there is a linear correlation between species richness and community services

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#Id: 5739

#Unit 10. Ecological Principles

Paul and Ann Ehrlich (1981) proposed an alternative called the rivet hypothesis Some species play a small but critical role in keeping the plane, the community, airborne, while other species do not

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#Id: 5740

#Unit 10. Ecological Principles

 Brian Walker (1992) proposed the Redundancy hypothesis Species that play the same roles in a community can compensate for each other if some are lost under particular conditions

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#Id: 5741

#Unit 10. Ecological Principles

Keystone hypothesis

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#Id: 5742

#Unit 10. Ecological Principles

Idiosyncratic hypothesis Community services change as the number of species increases or decreases, but that the direction of change is not predictable