Topic 7.3 Stem cells

Question 1

What is a stem cell?

Answer 1

Undifferentiated cells, that can divide and turn into other specific cell types.

Question 2

Name the three types of stem cell

Answer 2

Totipotent

Pluripotent

Multipotent

Question 3

Define totipotent stem cells

Answer 3

Can develop into any cell type including the placenta and embryo

Question 4

Define pluripotent stem cells

Answer 4

Can develop into any cell type excluding the placenta and embryo

Question 5

Define multipotent

Answer 5

Can only develop into a few different types of cell

Question 6

How can embryonic stem cells be used in medicine?

Answer 6

To treat a variety of diseases e.g. Parkinson’s, and replace damaged tissue e.g. nerve cells.

Question 7

What is the main ethical issue around embryonic stem cell use?

Answer 7

Embryos are killed in the process of extracting stem cells.

There are other issue too - e.g. Risk of infection when cells are tranplanted, rejection of stem cells and they may become cancerous

Question 8

How do totipotent cells develop into other types of stem cell?

Answer 8

Epigenetic modifications recult in selective translation of the relevent parts of the DNA. Totipotent cells develop into pluripotent cells in the early stages of embryonic development, and then later into fully differentiaited somatic cells.

Question 9

How are induced pluripotent stem cells (iPS cells) produced?

Answer 9

From fibroblasts (fully differentiated connective tissue). Genes for transcription factors are inserted, and the cell regains the ability to differentiate into other types of cell.

Question 10

Whys is the use of iPS stem cells favoured over embryonic stem cells?

Answer 10

More himane to produce. Less risk of infection when tranplanted. Can be created in large numbers.