MODULE TWO- STEM CELLS

What is the name of the intermediate ball of cells that a zygote develops into, before it becomes an embryo?

The blastocyst

What does a blastocyst consist of?

The trophoblast (outer layer) and the inner cell mass, ICM (inner layer)

What does the trophoblast of a blastocyst develop into?

The placenta

What does the inner cell mass of a blastocyst develop into?

The embryo

How does mitochondrial replacement therapy work?

• Egg from mother contains mitochondrial DNA with a mutation

• Nucleus of a donor egg is removed and nucleus from mother is transferred to egg

• Donor egg will contain healthy mitochondrial DNA from donor

What are ‘bad quality’ blastocysts used for?

Used to derive embryonic stem cells

Describe the concept of ‘differentiation path commitment’.

A pluripotent cell that could be anything becomes more and more differentiated at the expense of not being something else

What was the experiment carried out by Spemann and Mangold, and what did it show?

• (done with newts) Donor piece is taken from embryo of newt (‘organizer’) and transferred to an embryo of another newt

• After being left to develop, organism has two heads

• The donor piece was not destined to be a head- instead, donor cells sent signals to recipient cells (that were not supposed to become a head), forcing them to differentiate to become a head

How could you use stem cells to study ALS?

Using stem cells, scientists can make neurones that do die in ALS and neurones that don’t die in ALS (e.g eye cells- this is how Stephen Hawking is able to communicate). Study the difference between them

How could scientists create clones from stem cells?

• Take the nucleus containing the genetic material of the person to be cloned

• Mix it with an egg that has had its nucleus removed

• Allow egg to develop into a blastocyst

Why must scientists use induced pluripotent stem cells rather than clones to study disease?

Cloning is illegal

What was the first success of using induced pluripotent stem cells to treat disease?

Making motor neurones for a patient with ALS

How would you make a rat-mouse chimera?

Mixing rat pluripotent stem cells with the inner cell mass of a mouse

What are two potential advantages of cloning animals?

• Could potentially preserve endangered species

• To breed livestock with desirable traits

What was the first successful cloning of an animal?

Dolly the sheep