stem cells

Question 1

What are stem cells ?

Answer 1

undifferentiated cells that
- can divide repeatedly
- have the potential to differentiate into specialised cell types

This ability is called
- potency
- plasticity
the more potent a cell -> the more cell types it can become

Question 2

every cell contains t
he ——- ——— but only certain —- are expressed depending on the cell —-

Answer 2

same DNA, genes , type

Question 3

stem cells become specialised because

Answer 3

only specific genes are transcribed and translated

Question 4

what influences which genes are expressed ?

Answer 4

The environment

Question 5

These conditions trigger the

Answer 5

production of specific proteins that cause the cell to differentiate

Question 6

type of stem cells and their potency

Answer 6

• totipotent SC
• Pluripotent
• multipotent
• unipotent

Question 7

1. totipotent stem cells
   where’s it found ?
   can form what type of cells ?
   What can it become ?

Answer 7

Can form all types of cells, including embryonic and extra-embryonic tissues ( placenta )

-found in very early embryo
- A single totipotent cell can become a whole new organism

Question 8

2. Pluripotent stem cells
   where’s it found ?
   can form what type of cells ?

Answer 8

can form cells from the three germ layers
- Ectoderm - skin, nervous system
- Mesoderm - muscles, bones, connective tissue
- endoderm -internal organs ( liver, pancreas )

Question 9

3. multipotent stem cells
   where’s it found ?
   can form what type of cells ?

Answer 9

• found in adult tissues
• can differentiate into limited range of cell types
• example - bone marrow stem cells
  red marrow -> Blood cell
  yellow marrow -> cartilage, fat, bone cells

Question 10

1. unipotent stem cells
   where’s it found ?
   can form what type of cells ?

Answer 10

• can only form one specific cell type
• example : cardiac progenitor cells
• can only divide to form heart muscle cells

Question 11

potency ———– as cells specialise

Answer 11

decrease
totipotent -> pluripotent -> multipotent -> unipotent

Question 12

specialisation happens as more

Answer 12

genes are switched off

Question 13

2 sources of stem cells

Answer 13

embryonic stem cells
- collected from unused IVF embryos
- embryos donated for research rather than being discarded

adult stem cells
- extracted from places like bone marrow
- can be removed through a minor operation, but may cause discomfort

Question 14

comparing embryonic and adult stem cells
- potency
- source
- ethical issues
- risk of rejection
- medical potential

Answer 14

pluripotent multipotent
ivf embryos bone marrow, tissue
yes lesser
higher lower ( IF DONER IS PATIENT )
Higher more limited

Question 15

medical uses for embryonic stem cells

Answer 15

used to treat
- Parkinson’s disease
- spinal cord injuries
- type 1 diabetes
- severe burns
- potential for organ generation = reduced need for donors

Question 16

medical uses for adult stem cells - bone marrow transplants for :

Answer 16

• leukaemia
• lymphoma
• sickle cell anemia
• SCID
• also used in treating paralysis cases

Question 17

stem cell storage

Answer 17

• umbilical cord blood or placental tissue may be stored after birth
• offers genetically identical stem cells for future use
• ethical and economic concerns : often only accessible to wealthier families

Question 18

How are induced pluripotent stem cells made ?

Answer 18

1) start with specialised cells
2) reprogram using viral vectors to introduce transcription factors
3) these transcription factors turn on genes typical of pluripotent stem cells
4) resulting cells behave like embryonic stem cells, but are generally identical to the patients

Question 19

Advantage of Induced pluripotent stem cells

Answer 19

• NO need for embryo use
• no risk of immune rejection
• potential to treat many conditions