Jumping genes Regulation Not so simple Commentary

Barbara McClintock genetics

Jumping genes

• Something turns genes on and turns them off
• and, as it turns out, some genes move about.
• Barbara McClintock discovered the first transposons,
• responsible for random colorations of kernels of maize,
• naming them Activator and Dissociator.
• This disproved the theory that genes were fixed
• in their positions on their chromosomes,
• and introduced the uncomfortable fact
• that Mendelian inheritance and random mutations
• did not entirely explain genetic variation.

Regulation

• An archaeon, bacterium, or eukaryote
• does not need all its genes all the time
• but can express a gene to make a protein as needed.
• Cells of multicellular organisms differentiate
• to have different structures and functions
• even though they contain complete genomes.

Not so simple

• “Not so simple, buddy,”
• said the Voice of Reality to the Poet.
• “Remember all this evolved by chance.
• Your simple notions, your simple lines
• don’t begin to describe reality,
• let alone if you had to make them rhyme!”