Nerve membrane can be premised to allow posiive ions in. This results in depolarizaion and a message being sent. Acion potenial can be controlled by channelrhodopsin from chlamy. Remember: once light hits channelrhodopsin, it opens and allows ions to low. Pull out its nuclear dna and chop it up to obtain channelrhodopsin gene. Paste it into other dna in order to create recombinant molecules. One way is to get it where the gene originates from cdna genes can be created by reverse transcripion of mrna. Take mrna and reverse transcribe double stranded dna into cdna. One other way to get channelrhodopsin into mice from chlamy. Observe the bacteria: add genes into plasmids (circular chromosomes) and use them as our vehicles for transport. Geing them inside is not enough, however. Need it to be expressed in the plasmid chromosome. Thus, move eukaryoic gene --> prokaryoic gene. Biolisic gene gun delivers transgenes to plant nuclei.