20.2 Stem cells and totipotency

Question 1

define totipotency

Answer 1

Having the ability to differentiate into all cell types

Question 2

where are totipotent cells often found?

Answer 2

Early embryo stages (zygote)

Question 3

why do stem cells self-renew and differentiate?

Answer 3

self-renewal maintains the stem cell pool
differentiation replaces dead or damaged cells throughout your life e.g creates muscle or nerve cells etc..
differentiated cells produce different proteins

Question 4

list the types of stem cells

Answer 4

embryonic 
adult
umbilical
placental
induced pluripotent (iPS) stem cells

Question 5

where do we find embryonic stem cells?

Answer 5

blastocyst

the cells inside, the inner cell mass

Question 6

What is the outer layer of a blastocyst called?

Answer 6

trophectoderm

Question 7

what is the process of collecting embryonic stem cells for use?

Answer 7

remove from blastocyst
culture in a lab to grow more cells (in a fluid with nutrients)
differentiate cells into the specialised cell type required

Question 8

what potency to embryonic stem cells have?

Answer 8

early embryo stages are totipotent

later stages are pluripotent

Question 9

where do we find adult stem cells?

Answer 9

surface of the eye
brain
skin
breast
testicles
muscles
bone marrow
intestines (gut)

Question 10

what potency do adult stem cells have?

Answer 10

multi-potent

Question 11

what potency do umbilical cord blood stem cells have?

Answer 11

multi-potent

Question 12

where can we find placental stem cells

Answer 12

found in the placenta

Question 13

what potency do placental stem cells have?

Answer 13

multi-potent

Question 14

what types of cells can we differentiate adult stem cells into?

Answer 14

only specialised types of blood cell

red blood cells, white blood cells, platelets

Question 15

how do we create iPS cells?

Answer 15

collect a cell from the body
genetically reprogram, add certain genes to the cell
cell behaves like an embryonic stem cell and can now be differentiated

Question 16

what is an advantage of iPS cells?

Answer 16

no need for embryos

Question 17

define potency

Answer 17

a measure of how many types of specialised cell a stem cell can make

Question 18

define pluripotent

Answer 18

can make almost all types of specialised cells in the body

Question 19

define multipotent

Answer 19

can make multiple types of specialised cells, but not all types. e.g tissue stem cells

Question 20

define unipotent

Answer 20

can make one type of cell, derived from multipotent stem cells

Question 21

what are stem cells?

Answer 21

a stem cells is a cell that is able to replicate itself while maintaining an undifferentiated state, and is then able to differentiate into mature cell types

Question 22

generally, where can adult stem cells be found?

Answer 22

within most organs, where they replace dead or damaged cells

Question 23

where can we obtain stem cells?

Answer 23

spare embryos created during IVF : those that aren’t implanted can have stem cells removed from the inner blastocyst.
umbilical cord blood
adult stem cells obtained from several places, come in small quantities and are hard to harvest but are used to treat many cancers

Question 24

how are we currently using stem cells in research?

Answer 24

used in research about creating replacement human organs

therapeutic cloning

Question 25

describe the process of therapeutic cloning

Answer 25

the nucleus of an ovum is removed and replaced with the nucleus of a cell from the patient
the cell is then administered a small electric shock to start it dividing.
once it reaches the blastocyst stage, the stem cells could be removed and cultured to create genetically identical tissues for the patient
this research has been allowed by the government, but all embryos must be destroyed after 14 days to avoid human cloning.

Question 26

who would benefit from stem cell research

Answer 26

it could help people suffering from diseases caused by faulty cells