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Developmental Biology. > Stem Cells and Planarian Regeneration. > Flashcards

Stem Cells and Planarian Regeneration. Flashcards

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1
Q

What are stem cells?

A

They are unspecialised/undifferentiated cells that have the ability to divide and differentiate into many different and specialised cell types.

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2
Q

Are stem cells similar to normal cells?

A

Yes.

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3
Q

In order to form specialised or differentiated cell types, what do stem cells need to do?

A

Stem cells will divide via meiosis and then enter the pathway that leads to specialisation.

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4
Q

What are the 3 main types of stem cell?

A

Totipotent stem cells.

Pluripotent stem cells.

Multipotent stem cells.

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5
Q

What are totipotent stem cells?

A

Totipotent cells are formed in the PGCs in early embryos and are able to develop into any cell in the body.

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6
Q

What are pluripotent stem cells?

A

These stem cells can form 1 of over 200 cell types. These are cells that are formed on the blastocyst after 5 days.

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7
Q

What are multipotent stem cells?

A

They are found in foetal tissue.

And as stem cells in some adults.

Even though they are differentiated, they can divide into a number of different tissues.

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8
Q

Stem cells are categorised by what?

A

Their origin.

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9
Q

What are embryonic stem cells?

A

These are stem cells that originate from the inner cell mass of the extra embryonic tissue of 5-6 day old human embryos.

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10
Q

What are embryonic germ cells?

A

These are derived from the PGCs.

Or from the parts of the embryo that will differentiate into different body parts.

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11
Q

What are adult stem cells?

A

They are undifferentiated cells that are found in various parts of the adult body such as the gut.

They replace cells that are used up such as blood cells.

They are essential for repair in various parts of the body.

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12
Q

What are scientists using stem cells for?

A

They are working with embryonic and adult stem cells to try and produce revolutionary medical techniques that could cure some of the worst diseases around.

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13
Q

Why is the use of stem cells considered to be immoral?

A

There is controversy around the harvesting of stem cells from fertilised human embryos.

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14
Q

How could stem cells cure arthritis?

A

By re-generating cartilage.

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15
Q

How can stem cells re-generate a broken spinal cord?

A

If stem cells are placed into the damaged area, they will differentiate into the required tissue and heal the damage.

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16
Q

What kind of cancer is stem cells hoped to cure?

A

Leukaemia.

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17
Q

The introduction of stem cells into a person has led to what disease?

A

Cancer.

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18
Q

How can stem cells cure autoimmune disease?

A

By replacing genes that have been destroyed by our immune system.

E.g. It is hoped that stem cells can replace the insulin producing cells that were destroyed by the immune system.

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19
Q

How are stem cells harvested?

A

From the inner cell mass of an embryo and then cultured in a petri dish.

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20
Q

Stem cells often develop on top of a layer of what cells in a petri dish?

A

Fibroblast cells.

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21
Q

What do we do to stem cells once we have cultured them?

A

We can try and manipulate them to go down a certain pathway

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22
Q

What has been the main problem with dealing with stem cells?

A

Manipulating them to go down a certain pathway and form a certain cell.

23
Q

What is often used to manipulate stem cell differentiation?

A

A secret sauce.

24
Q

What does the secret sauce do to induce stem cell development?

A

It seems to provide the conditions that would occur in the embryo when the cells differentiate normally.

25
Q

Stem cells will often go down how many pathways?

A

2.

26
Q

How can we genetically manipulate stem cells?

A

By inserting DNA into the nucleus.

27
Q

Stem cells that are treated with retinoic acid will often differentiate into what kind of cells?

A

Neural cells.

28
Q

When treating mice with sickle cell anaemia, what cells are removed?

A

Fibroblast cells.

29
Q

What kind of mouse are the fibroblast cells removed from when using stem cells to cure SCA?

A

A mouse that is homozygous for sickle cell anaemia.

30
Q

How do we differentiate the fibroblast cells from a mouse that has SCA?

A

The cells are forced to excrete certain genes that force them to revert back to a stem cell like state.

31
Q

What is used to open the DNA structure when removing genes from the fibroblast cells of a mouse that has SCA?

A

C-MYC.

32
Q

What is used to establish pluripotency when removing genes from the fibroblast cells of a mouse that has SCA?

A

SOX-2.

OCT-4.

33
Q

What effect do C-MYC, SOX-2 and OCT-4 have on the genome of cells?

A

They open the genome of the cells up and allow dormant genes the chance to be expressed while other genes that were active are suppressed.

34
Q

What does the genetic mutation of a cells genome allow us to do?

A

They allow us to target a mutant gene and replace it with a good copy.

35
Q

Once the altered cell is placed into the mouse with SCA, what will happen?

A

It will replicate leading to the cure of sickle cell anaemia.

36
Q

What is the benefit of taking a cell from the body and altering its genome to fix any defects?

A

There is no ethical dilemma as these cells are harvested from the body and not fertilised foetus’.

37
Q

Can problems in stem cells be derived from contaminations in the petri dish?

A

Yes.

38
Q

What happens if the stem cells are not compatible with the patients immune system?

A

They will get destroyed.

39
Q

What are the best re-generating organism that we know?

A

Planarians.

40
Q

If we cut a planarian into many pieces, what will happen?

A

Each piece will re-generate into a new planarian.

41
Q

What is one of the main problems that planarians face with regeneration?

A

Each segment needs to work out what needs to be regenerated.

42
Q

What allows planarians to re-generate?

A

Neoblast stem cells that are scattered throughout the body.

43
Q

Where are neoblast stem cells not found in the planarian?

A

Near the eyes.

44
Q

What gene needs to be present for eye regeneration in planarians?

A

PAX-6.

45
Q

Where is PAX-6 expressed in the planarian?

A

All over the body.

46
Q

What gene is expressed in the cephalic ganglia and nerve cords of the planarian?

A

GTPAX-6A.

47
Q

What is one of the 1st genes to be expressed in the developing planarian?

A

GTPAX-6A.

48
Q

What is the antisense technique?

A

The silencing of genes by synthesising a double strand of RNA that is complementary to a target. E.g. PAX-6.

It will bind to and degrade the RNA of PAX-6, silencing the gene.

49
Q

What do we use to synthesise the RNA in the antisense technique?

A

A plasmid.

50
Q

How do we get a plasmid for the antisense technique into a planarian?

A

They eat bacteria.

Insert a genetically modified bacteria and feed it to them.

51
Q

If PAX-6 is removed from a planarian, will there be eyes present when it re-generates?

A

Yes.

This means the eyes can develop without PAX-6.

52
Q

What genes are responsible for the development of the cells in the anterior posterior axis of the planarian?

A

The HOX genes.

53
Q

What are the 2 HOX genes responsible for re-development of the planarian?

A

DTHOX-E and DTHOX-F.

Developmental Biology. (21 decks)

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