7.2.3 - Stem cells and differentiation

Question 1

What are stem cells?

Answer 1

Unspecialised cells that can divide and develop into other types of cell

Question 2

How do stem cells become specialised?

Answer 2

Genes that are expressed get transcribed into mRNA which is then translated.
These proteins will modify the structure of the cell

Question 3

What are totipotent stem cells?

Answer 3

Occur for a short length of time in mammalian cells (before development and growth of embryo)
can create any cell type

Question 4

What are pluripotent stem cells?

Answer 4

Occurs in the embryo, can create most cell types

Question 5

What are multipotent stem cells?

Answer 5

Found in mature mammals, can oly produce a limited amount of cells

Question 6

What are unipotent stem cells?

Answer 6

Found in mature mammals, can only differentiate into one cell type

Question 7

Comment on the potency of:
1) Embryonic stem cells
2) Adult stem cells
3) Umbillical cord stem cells

Answer 7

1) Totipotent
2) Multipotent
3) Pluripotent

Question 8

Where are the following stem cells found?
1) Embryonic stem cells
2) Adult stem cells
3) Umbillical cord stem cells

Answer 8

1) Early embryo before blastulation
2) In organs, bone marrow
3) Umbillical cord

Question 9

What happens to the embryo when embryonic stem cells are removed from it?

Answer 9

The embryo is destroyed

Question 10

What happens to the stem cells in a zygote as it divides?

Answer 10

They start as totipotent and then become pluripotent as they divide

Question 11

Why do the stem cells in an embryo become pluripotent when they totipotent initially?

Answer 11

Due to transcription factors and epigenetic controls switching on and off the transcription of certain genes.
Parts of the chromosome may become supercoiled to prevent genes from being read silencing them