2.6 Stem Cells Flashcards

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1
Q

what are stem cells?

A

unspecialised cells that can divide by mitosis and potentially differentiate into any type of cell during development

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2
Q

give examples of where stem cells can be found:

A

embryos
umbilical cords
bone marrow

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3
Q

what is potency?

A

a stem cells ability to differentiate into different cell types
the more cells it can differentiate into the greater it’s potency

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4
Q

what are totipotent stem cells?

A

can differentiate into any type of cell they have the potential to form a whole organism

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5
Q

what are pluripotent stem cells?

A

can form all tissue types but not whole organisms

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6
Q

what are multipotent stem cells?

A

only form a range of cells within a certain type of tissue

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7
Q

how do cells become specialised?

A

certain genes are expressed, the rest are switched off

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8
Q

where are totipotent stem cells found?

A

zygotes

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9
Q

after 7 days a blastocyst forms and the stem cells become what?

A

pluripotent

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10
Q

when are tissue stem cells present?

A

from birth

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11
Q

give an example of where tissue stem cells are found:

A

bone marrow

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12
Q

tissue stem cells are what type of stem cell?

A

multipotent

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13
Q

give examples of where multipotent adult stem cells can be found:

A
liver 
pancreas
umbilical cord
spinal cord
bone marrow
skin
blood
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14
Q

adult stem cells are multipotent and can be triggered to become what?

A

pluripotent

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15
Q

why are stem cells found in umbilical cords useful for research?

A

in plentiful supply
non invasive
can be stored

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16
Q

where is plant meristematic tissue found?

A

tips of roots and shoots where growth is occurring

between xylem and phloem - known as vascular cambium

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17
Q

what can cells from the vascular cambium do?

A

differentiate into xylem and phloem

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18
Q

what is the potency of the plant stem cells?

A

pluripotent (remain pluripotent throughout a plants life)

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19
Q

what is a RBCs average life span and why?

A

120 days

lack of organelles & nucleus (akaryotic)

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20
Q

stem cells in the bone marrow produce how many RBCs per kg of body mass per day?

A

3 billion

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21
Q

how long do WBCs live?

A

6 hours

22
Q

how many WBCs does bone marrow produce?

A

1.6 per kg per hour

23
Q

when does the no. of WBCs the bone marrow produces increase?

A

during infection

24
Q

what are the stem cells in the bone marrow called?

A

haematopoietic stem cells

25
Q

the ability of stem cells to differentiate means they have the potential to do what?

A

be transplanted and replace damaged tissues

26
Q

what often happens as a result of a heart attack? what could stem cells do?

A

muscle tissue becomes damaged

stem cells could be used to replace the damaged tissue (has been tried experimentally with some success)

27
Q

what happens to a persons beta cells in type 1 diabetes?

A

the bodys immune system attacks them so they don’t produce insulin

28
Q

what do stem cells have the potential to do in type 1 diabetes?

A

create new insulin producing cells

29
Q

what happens in Alzheimer’s disease?

A

nerve cells dies interrupting the interconnections of the cortex (involved in memory, personality and behaviour) resulting in memory loss

30
Q

how could stem cells be used to treat Alzheimer’s ?

A

grown into nerve cells to replace those that have died in the brain repairing the damage of Alzheimer’s

31
Q

what happens in Parkinson’s disease?

A

death of dopamine producing cells in the brain resulting in shaking & trembling

32
Q

how could stem cells be used to treat Parkinson’s?

A

using stem cells to create new dopamine producing cells

33
Q

with research into stem cells and Parkinson’s what problem has arisen?

A

producing enough reliable dopamine producing cells

34
Q

which stem cells show the greatest promise for treating parkinsons?

A

embryonic - totipotent

35
Q

which stem cells is it not possible to treat Parkinson’s with currently?

A

adult stem cells

36
Q

what is macular degeneration?

A

macula of the retina (light sensing nerve tissue at the back of the eye) deteriorates causing blindness in elderly & diabetics

37
Q

how could stem cells be used to treat macular degeneration?

A

replace the deteriorating nerve tissue

38
Q

what have scientists already done using stem cells, in rats & mice?

A

reversed birth defects

restored movement in some with damaged spinal chords

39
Q

what does gene therapy involve?

A

inserting healthy genes into a cell to replace faulty ones in the hope of treating a disease

40
Q

why would stem cells be beneficial in gene therapy?

A

they have the ability to self renew so the need to provide repeated administrations of gene therapy would be reduced

41
Q

stem cells are used in developmental biology to help us understand more about what?

A

developmental disorders & cancers

42
Q

stem cell use has the risk of what?

A

rejection of foreign tissue grown from stem cells by the patient’s immune system
risk of developing tumours & cancers

43
Q

what is an issue of the use of embryo’s for stem cells?

A

removal of stem cells results in the destruction of the embryo (religious & moral issues)

44
Q

where are embryos used for stem cell research from?

A

left over from IVF

law changes mean embryos can be created in a lab as a source of stem cells

45
Q

embryonic stem cell transplantation carries the risk of tumour formation why?

A

during normal growth, cell division & specialisation follow a set program which can be affected when stem cells are taken, cultured & transplanted

46
Q

why are adult stem cells and umbilical chord stem cells restricted in usefulness?

A

they are multipotent and are more likely to mutate

47
Q

What are many drugs in medicine derived from?

A

Plants

48
Q

Plant stem cells can be cultured leading to what?

A

An unlimited supply of cheap plant based drugs

49
Q

What is paclitaxel and what is it used for?

A

Common drug used in treatment of lung & breast cancer obtained from bark of yew trees

50
Q

Why is the supply of paclitaxel limited?

A

Trees have to be mature

51
Q

Recently stem cells of the yew trees have been used to do what?

A

Produce the drug cheaply in sustainable quantities

52
Q

Why do us of plant stem cells face few ethical issues?

A

Human life is not harmed in the process