Stem cells

Question 1

what are the properties of stem cells

Answer 1

to self replicate
to be able to differentiate

Question 2

what are the two types of stem cell devision

Answer 2

Asymmetric devision
symmetric devision

Question 3

what are the different levels of potency in stem cells

Answer 3

totipotent
pluripotent
multipotent
unipotent

Question 4

from what stage of embryonic development are embryonic stem cells taken from

Answer 4

the inner cell mass in the blastocyst. These cells are pluripotent.

Question 5

how is the inner cell mass removed from the blastocyst

Answer 5

immunosurgery
micromanipulation
lazer disection

Question 6

how does immunosergery work

Answer 6

the blastocyst is incubated with antibodies that recognise the cells membrane proteins
unbound antibodies are then washed away
compelment proteins are added which lyse the decorated cells, leaving only the inner cell mass

Question 7

how does micromanipulation work

Answer 7

a very fine needle is inserted into the blastocyst. the inner cells are the sucked out of the blastocyst.

Question 8

how does laser dissection work

Answer 8

the blastocyst is cut open with a laser and the inner cell mass is then removed by tweezers.

Question 9

what genes are over expressed to induce pluripotentcy in adult cells

Answer 9

Oct4, Sox2, Klf4, c-myc

Question 10

what are IPSCs

Answer 10

induced pluripotent stem cells

Question 11

what are reprogramming waves

Answer 11

the reprogramming of IPSCs occurs in two waves before becoming pluripotent stem cells

Question 12

what is PiggyBac

Answer 12

a human vector that contains all four yamanaka factors that can reprogram an adult cell into a IPSC.

Question 13

why are retroviruses not used as a IPSC vector when the stem cells are used in therapy

Answer 13

retroviruses integrate the gene into the genome of the cell, which leaves a footprint. This could lead to cancerous mutations down the line.

Question 14

how are pluripotent stem cells cultured in vitro

Answer 14

stem cells need a living media to grow. they are grown on top of a layer of fibroblast cells which provide the required growth factors and metabolites.
the layer of fibroblasts (feeder layer) are pretreated with UV or gamma rays to stop them from proliferating and taking over the culture.

Question 15

what are feeder free cultures

Answer 15

feeder layers will result in some variability since different feeder cell cultures are exactly the same. scientists are looking to use new methods (feeder free layers) to grow stem cells

Question 16

what are embryoid bodies

Answer 16

in a solution, stem cells will agregate in the same way they would in the blastocyst, forming an embryo like structure.
embryoid bodies can stimulated to differentiate into different cell lineages similar to an embryo.