Stem cells 6.5

Question 1

what is differentiation and what does it involve

Answer 1

• process of cell becoming specialised
• involves expression of some genes but not others in the cell’s genome

Question 2

what are stem cells

Answer 2

Undifferentiated/unspeciliased cells that originate from mitosis and meiosis

Question 3

once stem cells are differentiated what happens to them

Answer 3

they enter G0 which means they lose the ability to divide

Question 4

what is the function of stem cells and what about them allow it to carry out this function

brief

Answer 4

• generate cells needed for growth and tissue repair
• able to undergo division continuously so these can be done perpetually

Question 5

why does stem cell division have to be strictly controlled

Answer 5

• if not fast enough will lead to ageing and unefficently growth and repair
• if too fast can lead to tumors (cancer)

Question 6

what is meant by a stem cells potency

Answer 6

A stem cells ability to differentiate into different cell types is called potency. The greater the number of cell types it can differentiate into, the greater its potency

Question 7

what are totipotent stem cells

Answer 7

• these stem cells can differentiate into any type of cell
• totally potent

Question 8

what are pluripotent stem cells

Answer 8

• can form ectoderm, endoderm and mesoderm but not whole organisms.
• present in early embryos

Question 9

what is a multipotent stem cells

Answer 9

• can form a range of cells within a certain type of tissue
• e.g. Haematopoetic stem cells in bone marrow can become various blood cells

Question 10

what influences a stem cell to differentiate into a specific type of cell

Answer 10

It is dependent on the function of the tissue, organ and organ system to which the cell belongs

Question 11

what are sources of animal stem cells found in both early and later life

Answer 11

Embryonic stem cells and tissue (adult) stem cells

Question 12

explain what embryonic stem cells are and there characteristics

Answer 12

• found in early embyros
• are totipotent
  ^after 7 days blastocyst forms and stem cells are pluripotent until birth

Question 13

what are the characteristics of adult tissue stem cells

Answer 13

• found in specific areas such as bone marrow
• They are multipoint
• they can be artificially triggered to become pluripotent.

Question 14

where can stem cells be found in plants

Answer 14

• found in meristematic tissue
• found wherever plant is growing
• also located in vascular cambium

Question 15

what illnesses and diseases can be treated by the transplantation of stem cells to affected sites

Answer 15

• heart disease
• parkinsons disease
• alzheimers disease
• spinal injuries

Question 16

what are some ethical concerns there could be about the use of stem cells (especially embryonic)

Answer 16

• moral obligations to using embryos as people consider destruction of embyros mudered life

Question 17

what could be done to overcome the ethical issues involved with embryonic stem cell harvesting

Answer 17

• use of umbilical cord stem cells
  ^however multipotent not pluripotent
• use of plant stem cells
• Induced pluripotent adult stem cells