Stem cells and gene switching What is the difference between stem cells and differentiated cells? Starter: Watch this clip and see if you can figure out what is going on

Learning Outcomes outline the sources and potential medical applications of stem cells H: briefly outline the stages involved in mammalian cloning H: recall that it is possible for scientists to reactivate inactive genes in the nucleus of a body cell to form cells of all tissue types

A central problem for biologists: All body cells have the same genetic material. But not all body cells are the same. How does this happen??!?!

6 mark Q – 6 minutes Humans all develop from 1 cell. Explain in detail, how it is possible for a human to end up with so many types of cell. (think mitosis and cell specialisation) Task: answer this question and write a marking scheme to go with it. (1 mark will be for SPAG)

We start off like this : A fertilized egg cell divides to form cells for a new individual.

zygote mitosis embryo Blastocyst (ball of cells containing embryonic stem cells which are unspecialised. Implantation (cells now start to specialise) mitosis

Go Round the room to fill in your fact sheet. 10 mins

Focus- therapeutic cloning Read the article and use it to describe what gene therapy is and some uses.

Card Sort Come up with your own grouping system to sort out the cards e.g. fact, opinion (for and against) and theory. Select the most important card from each section Discard any irrelevant or weak arguments/ facts

Task Complete the exam questions. Some you need to answer – some you need to mark. Use the mark scheme to help you.

Use of embryonic stem cells. Sources: Aborted foetuses, milk teeth, umbilical cord.

The cells produced are genetically identical to other body cells so there is no risk of rejection. Genes can be switched back on in order to change the type of cell produced.

This is called Therapeutic Cloning