MODULE ONE- STEM CELLS

What is cell differentiation?

The process by which a stem cell becomes a specialised cell type

What does pluripotent mean?

A cell that has the potential to become all the cell types of the body

What determines a cell’s germ layer?

Its location within the embryo and the chemical signals it receives

What are the three germ layers known as?

Endoderm, ectoderm, mesoderm

Once a stem cell has differentiated into a germ layer, what potency does it have?

Multipotent

What does multipotent mean?

A cell that can make many cell types within its germ layer

What does unipotent mean?

The cell can only become one cell type

What can ectoderm cells become?

Many different cell types, for example skin cells or neurones

What can mesoderm cells become?

All types of muscle cells, for example heart muscle, skeletal muscle

What can endoderm cells become?

Many of the cells in our organs, for example lung cells, thyroid cells, pancreatic cells

How do you create induced pluripotent stem cells?

• Add a combination of four proteins (known as transcription factors) to normal adult skin cells that must be dividing

• Transcription factors remove cell’s identity markers

• Cell acts in same way as a stem cell would

What are the two features needed in order for a cell to be a stem cell?

• Cell must be self-renewing

• Cell must be multipotent

What does self-renewing mean?

Stem cell can replicate itself into more cells of the same unspecialised cell type

What are embryonic stem cells?

Pluripotent stem cells found in an embryo

What are cord blood stem cells?

Pluripotent stem cells found in an umbilical cord, taken after a baby is born

What are adult stem cells?

Multipotent stem cells found in the adult body

What is bone marrow?

A spongy tissue found inside some of our bones that is abundant with stem cells

In which organs do stem cells regularly divide?

Gut and skin

In which organs do stem cells only divide under special conditions?

In the brain and heart

Why are stem cells important (four reasons)?

• For studying early human development (mice and human embryos are too different to be able to use mice to study)

• Studying disease (can create iPS cells from mutated cells to model disease arising from mutation)

• Drug development (use disease model from point two to look for drugs which can cure the disease, test for some side effects in a dish, not on subjects)

• Cell transplantations (can be used to restore or replace damaged tissue, can potentially 3D print organs using stem cells in future)

What is regeneration?

The reactivation of development in later life to restore missing tissues

Give four examples of organisms that can regenerate their limbs

Salamanders, cockroaches, starfish, axolotls

What can axolotls regenerate, and what’s special about their regeneration?

They can regenerate their limbs, spinal cord, jaw, tail, skin without scarring

What is special about flatworm regeneration?

They can regrow into complete organisms after being cut, flatworms which have been decapitated keep their memory

What is the meristem?

Plant stem cells found in shoots and roots to help plants grow in length, grow flowers, grow roots etc.