Stem cells (easy)

Question 1

Describe the characteristics of an iPSC [2]

Answer 1

1. UNDIFFERENTIATED/UNSPECIALISED cell capable of undergoing PROLIFERATION and SELF-RENEWAL
   » proliferation = daughter cells of varying differentiation potential
   » self-renewal = daughter cells of same differentiation potential
2. Capable of forming all cell types of an organism except EXTRAEMBRYONIC TISSUE
3. Can DIFFERENTIATE to produce specialised cells upon receiving MOLECULAR SIGNALS
4. Normal adult somatic cells that are reprogrammed to be pluripotent

Question 2

Suggest why it is necessary to introduce the Yamanaka factors in iPSC formation [1]

Answer 2

They are methylated/silenced in differentiated somatic cells, but not in PSCs

Question 3

Describe 2 similarities between ESCs and iPSCs [2]

Answer 3

1. Pluripotent
   » Can differentiate to form an entire foetus except extraembryonic tissue
   » Undifferentiated/unspecialised
2. Can self-renew and divide continually (active telomerase)
3. Similar DNA methylation patterns

Question 4

Suggest why Yamanaka factors must be removed before stimulating differentiation [1]

Answer 4

Yamanaka factors allow cells to remain pluripotent&raquo_space; impedes differentiation

+ reduce risk of insertional mutagenesis???

Question 5

Describe the normal functions of ESCs [2]

Answer 5

1. Form ICM of BLASTOCYST&raquo_space; develops into the foetus

2. PLURIPOTENT - differentiate into all cell types of an organism except extraembryonic tissue (placenta)

Question 6

Describe 2 pros and 2 cons of both ESCs and iPSCs

Answer 6

PROS:

• pluripotent&raquo_space; any type of cell
• easily cultured in laboratories in large quantities

CONS:

• self-renewal&raquo_space; risk of uncontrolled CD&raquo_space; tumour formation
• differentiation of cells is hard to control&raquo_space; unintended types of cells