cell differentiation and stem cells

Question 1

define the different stem cell potencies

Answer 1

• omni - can differentiate into any cell type including placenta
• pluri - can differentiate in to any cell type other than placenta
• multi can differentiate into a few cells types
• unipotent a reserve population that can be used to regenerate new cells of one lineage

Question 2

Give 3 examples of ectoderm derived cells

Answer 2

skin cells, neuron, pigment

Question 3

Give 3 examples of mesoderm derived cells

Answer 3

bone, cartilage, muscle
cardiac muscle
heart, blood blood vessels
rbc

Question 4

Give 3 examples of endoderm derived cells

Answer 4

gut tube derivatives eg: lung, thyroid, pancreas

Question 5

what do transcription factors do

Answer 5

determine which genes are switched on and off

Question 6

what is the relationship between transcription factors and specification

Answer 6

assorted TFs can be switched off and on at various points during specification thereby changing the gene expression (and so spec/differentiation)

Question 7

what can influence cell fate?

Answer 7

internal and external factors eg ECM

Question 8

what are the 2 commitment stages and what are their features

Answer 8

1) Specification - capable of differentiation autonomously in a neutral env. but can be reversed in a non-neutral env
2) determination - capabale of differentiating even when moved about. Pretty much irreversible

Question 9

Define:
Dedifferentiation
Transdetermination
Transdifferentiation

Answer 9

Dedifferentiation in which a cell reverts to a less-specialized progenitor state within a discrete lineage(F allows re-population of the stem cell population).
Transdetermination in which a cell dedifferentiates to a less-committed progenitor state and then switches lineages to re-differentiate to a cell type in a new lineage.
Transdifferentiation in which a cell moves directly from one lineage to another without moving through a dedifferentiated or pluripotent intermediate €

Question 10

what can cause necrosis

Answer 10

trauma, disease, infection

Question 11

Define the process of apoptosis

Answer 11

Membrane blebbing, shrinkage of cell, nuclear collapse (nuclear fragmentation, chromatin condensation, chromosomal DNA fragmentation), apoptoticbody formation. Then, engulf by white blood cells

Question 12

define necrosis process

Answer 12

Membrane disruption, respiratory poisons and hypoxia which cause ATP depletion, metabolic collapse, cell swelling and rupture leading to inflammation

Question 13

give 3 treatments for necrosis

Answer 13

antioxidants
debridement
maggot debridement

Question 14

What benefits does maggot debridement have?

Answer 14

secrete antibacterial substances
do not eat healthy tissue
promote healing

Question 15

why does apoptosis happen in foetal development

Answer 15

fingers and toes, caudal eminence, nervous system, 50% more cells than needed

Question 16

50-?bn cells ___ each___ in an ___

Answer 16

die, day, adult

Question 17

what are caspases?

Answer 17

initiators and executioners(!) of apoptosis

Question 18

which are initiator caspases?

Answer 18

2,8,9,10

Question 19

which are executioner caspases

Answer 19

3,6,7

Question 20

describe the intrinsic and extrinsic apoptosis pathways

Answer 20

intrinsic: cell notices it’s a bit knackered, targets the mitochondria. Cytochrome C is released which activates Caspase 9, then activating the executioner caspases

Extrinsic:
cell receives death ligands bound to its death receptors. Caspase 8 is activated by the DED domain and that activates the executioner caspases

Question 21

name the type of cells which closely reside with stem cells, limiting their environment

Answer 21

stroma cells

Question 22

Name 2 ways in which stem cells differ from other cells

Answer 22

They can divide to renew themselves indefinitely
* Self-renew
They can generate specialized (differentiated) cell types
* Multipotent or unipotent
The environment around them controls their activation
* Niche

Question 23

how is a constant pool of stem cells maintained?

Answer 23

symmetric and asymmetric division

Question 24

how does asymmetric cell division happen (2)

Answer 24

asymmetric distribution of cell fate determinant during mitosis or facing one daughter cell away from the niche (different environment

Question 25

what’s a haemocytoblast

Answer 25

blood cell stem cell

Question 26

name 5 types of blood cells

Answer 26

erythrocyte
mast cell
B/T lymphocyte
basophil
neutrophil
eosinophil
macrophage

Question 27

name some other stem cell populations

Answer 27

Skin
Hair
Gut
Bone
Muscle
Neuronal

Question 28

name the steps of artificially using stem cells to make a skin graft

Answer 28

biopsy
cell isolation
cell proliferation
scaffold
tissue development
implantation

Question 29

what are iPS and what can you do with them

Answer 29

induced pluripotent cells. Ie somatic cells whcih have been reprogrammed back ro pluripotent cells

make tissue

Question 30

what i senescence

Answer 30

irreversible cell hibernation forever.

Question 31

what causes senescence

Answer 31

same stimulus as apoptosis

Question 32

what happens to telomeres over time

Answer 32

get shorter

Question 33

what happens if there’s too much telomerase?

Answer 33

stem cells proliferate more efficiently and can lead to cancer