Warm-Up 3/12/12

•What is the purpose of gel electrophoresis?•To which end of a gel box (+ or -) will DNA

travel? Why?Answers: The purpose is to separate

molecules by size and charge in an agarose gel. DNA travels to the positive end of a gel box because it is negatively charged.

Turn in your purple GE Virtual Lab and yellow GE Pre-Lab to be stamped/returned at my leisure.

Goals for this week

•Review stem cells, gene therapy, and gel electrophoresis basic content

•Learn about cloning•Learn the Dye Lab procedure and practice

micropipetting skills for next week’s gel electrophoresis labs

Put a new entry in your lab book table of contents: Biotechnology Practice Questions

Also, take out your Gene Therapy and Stem Cells Guided Notes

Gel Electrophoresis Practice Question•Copy the drawing of the agarose gel from

the board.•For each sample (A-D), predict which

direction and relatively how far each sample will travel through the gel. Draw your prediction on the gel.

A = positively charged, smallB = positively charged, largeC = negatively charged, smallD = negatively charged, large

Stem Cells Practice Question•What is the difference between a

totipotent, pluripotent, and multipotent stem cell? Which is used most by researchers in attempting to re-grow dead cells?

Stem Cells Answer•Totipotent stem cells are fertilized eggs (0-1

days old). They can become any cell type.•Pluripotent stem cells are 4 day old embryos

that can become over 200 cell types.•Multipotent stem cells are ‘adult’ stem cells

that regenerate skin, blood cells, etc.•Most research is done using pluripotent

stem cells- they are easiest to ‘catch’ and have the most possibility

Gene Therapy Practice Question•Explain how gene therapy could be used

to: a: cure a genetic disorder in an adultb: change the genes present in human

embryos to create a ‘designer baby’

Gene Therapy Answer• In gene therapy, beneficial human genes are

cloned inside bacteria and then loaded into empty virus shells. The virus is injected into people with genetic disorders. The beneficial genes should join the DNA of the patient when the virus injects its DNA into host cells, replacing the defective gene causing the disorder.

• Gene therapy could be used to deliver genes for beneficial and/or desired traits directly to embryos. The virus would infect the embryo cells with the desired genes just like described above.

Designer Babies Practice Question•A couple decides they want to produce a

disease-free male heir. Explain how In-Vitro fertilization can be used to select for this child

•http://www.flickclip.com/flicks/jurassicpark3.html

Designer Babies Answer•First, sperm from the father and eggs from the

mother would be united in a Petri dish, making multiple embryos to select from. Then, each embryos DNA would be run through a computer program comparing it to normal DNA to find which embryos have which genetic disorders. Also, each embryo would be screened for a Y chromosome. Disease-free embryos with the chromosome combination XY would be selected and implanted back into the mother’s uterus.

How We Clone Animals1. Cells from desired animal are stored in

petri dish2. An egg from another animal is used to

grow the desired clone- Egg’s nucleus is removed- Nucleus from desired cell is inserted- Egg grows into blastocyst- Blastocyst is implanted into surrogate

mother

This is called Somatic Cell Nuclear Transfer

Cloning Clips

•http://www.pbs.org/wgbh/nova/nature/t-rex-blood.html

Biotechnology Practice Question•Of the three biotechnology advances you

have learned about (designer babies, gene therapy, stem cells), which do you find the most promising for improving human existence? Why?