Animated GIF: Extracellular electron transfer to soluble iron. Example of Geobacter respiration

extracellular electron transfer, geobacter
Electrons: yellow
iron: black
MacA protein: dark green
PpcA: blue
OmcB: black
other outer membrane cytochromes: orange and light green

When Geobacter are in an environment where soluble iron is present, this can serve as the terminal electron acceptor in metabolism through an elaborate electron highway.

Bacteria Chemotaxis Explained with Animated GIFs. Bacterial Behavior in Motion

bacteria, chemotaxis, random bias
With no attractant or repellant, bacteria have a “random bias”. This means they switch direction randomly.
bacteria, chemotaxis, attractant response
When bacteria are in an attractant gradient (colored orange), they switch direction less often when attractant concentration is higher.
bacteria, chemotaxis, repellant response
However, when a repellant is present (colored red), bacteria switch direction more often in high repellant concentrations.