DNA identification: Read the story and then answer: How did you save Dr. N time when you said: 'third row'?

Read the following then proceed to the laboratory portion of this activity.








Imagine this. It's fourth period and you arrive at your Science class to find (dramatic music please) ... a substitute teacher!





Who is this guy with the glasses and pocket protector you wonder.





His name is Dr. Nerdlicious. He proudly announces that fact along with the list of PHd's, Nobel prizes and Jeopardy championships he's got on his resume.





The courteous and respectful student that you are, you make your way to your seat (before the bell of course) open up your notebook and set your pen upon the desk. Hey, why should learning stop just because the regular teacher isn't in?





Some of the class neer-do-wells are giving the sub a hard time as he distributes a few dittos. Making loud noises, calling out, asking purposely dumb questions.





It happens as Dr. Nerdlicious turns his back to the class to write the assignment on the board. A wad of gum whizzes right past the bespectacled genius and sticks to the slate mere centimeters from the chalk in the good doctor's hand.





You wonder how the sub is going to handle this. You know it's a make or break move. The wrong reaction and this class is history; the hooligans will take over the asylum. The right move and Dr. Nerdlicious will survive to teach another day.





The sub turns slowly toward the class. You can't read any emotion on his face. Is he too angry or terrified to speak? Still without so much as blinking he makes his way to his brief case which lies atop the teacher's desk at the front of the room. Though his stare never leaves the class he manages to open the case.





Click! the locks on the professor's case seem to echo in the room. Now no one is talking or moving. Everyone is waiting for Dr. Nerdlicious's next move.





He reaches in to the briefcase. (To every student his eyes appear locked on them personally.) The classes collective breath is held. His hands withdraw from behind the cover of the briefcase revealing ... revealing ... revealing ... a stack of envelopes.





Nobody knows what to say. What do you do when the sub pulls out envelopes?





Nerdlicious hands out the envelopes. Eyes never leaving the students. He directs each person to put their name on the outside of the envelope, lick and seal it. He is like a robot in giving directions, still emotionless. Confused looks spread throughout the students. He collects the envelopes, staring into the eyes of each child and saying their name as he adds their contribution to the stack.





For the rest of the period there is a stale mate. Nobody talks. Not the doctor, not the thugs, not nobody! The bell eventually rings and the students exit the room in eerie silence.





Dr. Nerdlicious closes the door behind the last student. Click.





Halfway to period five you realize that in your stunned condition you left your pen on your desk. Being the fastidious student that you are, you trot (ok so you do break some rules) back to pick up your writing implement.





As you open the classroom door you see the substitute teacher at the board. He's wearing latex gloves and appears to be scraping the aforementioned 'masticated projectile' (the gum) into a small Petri dish. The thin dish is covered, taped shut and placed into the briefcase along with the small spatula and the rubber gloves.





He catches you off guard by calling you by name. He poses a question to which you reply, ';Third row. Sir.';





You grab your pen and fumble out of the room.





It's the next day. Again it's period four. Dr. N intently stares at each student as they enter the room. The bell rings and on one is talking. Even yesterdays hooligans are stone faced and silent. You look over to where they sit and you notice one of them is missing.





Dr. N barks four words before beginning class. ';Don't mess with me.';





And nobody does.DNA identification: Read the story and then answer: How did you save Dr. N time when you said: 'third row'?
You told him that the offending party sat in the third row. Knowing this, he only had to sequence the DNA of the kids in that row in order to compare them to the DNA left in the saliva on the gum.