One can isolate the gene for human insulin from human cells, and put that gene into a plasmid (small circular DNA molecule). That plasmid is then put into bacterial cells, and the bacteria produce insulin as coded for by the human gene. It is necessary to include the neccessary bacterial promoters etc, so that the cell can actually read the DNA message, but because the genetic code and the language of codon/anticodon/mRNA/tRNA etc. is universal, a gene in one organism is readable by another organism.
A gene from one organism can be expressed in another, because the size and structure of all genes is exactly the same (of course, the code is different). Scientists insert a gene from organism “A” into the gene of organism “B”. They do this by first cutting the gene of organism “B”, and inserting gene “A”. Then, (this wasn’t in the lesson. I’m just guessing) certain proteins inorganism “B”, which are responsible for gene repair, connect gene “A” to genes “B” properly. When it is time for transcription to take place, the enzyme/proteins read the new DNA also, including it in the RNA sequence
Cytotoxic T cells secrete granzymes and perforins when targeting cells. Additionally they secrete cytokines such as IFN-, TNF-α and TNF-β that act to activate macrophages and help kill infected cells.
