2.1.6 cell division, cell diversity and cellular organisation > stem cells > Flashcards

stem cells Flashcards

(58 cards)

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1
Q

what is a stem cell

A

unspecialised cells able to express all of its genes and dividse by mitosis

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2
Q

what is differentiation

A

process by which stem cells become specialised into different types of cells

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3
Q

what does differentiation involve

A

the expression of some genes but not others

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4
Q

what is important to note about different cells in multicellular organism

A

they are specialised for different functions. despite being differentiated in structure and function all body cells within an organism have the same DNA (except those without a nucleus)

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5
Q

what do all cells begin as

A

undifferentiated cells originating from mitosis or meiosis

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6
Q

what is the name for unspecialised cells with the ability to differentiate to become any of the range of specialised cells

A

stem cells

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7
Q

what are stem cells able to fo

A

undergo division repeatedly and are the source of new cells necessary for growth, development and tissue repair

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8
Q

what happens once stem cells become specialised

A

they lose the ability to divide (entering the G0 phase of the cell cycle)

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9
Q

why does the activity of stem cells have to be strictly controlled

A

if they dont divide fast enough, then tissues arent repaired efficiently enough which can lead to ageing
however, uncontrolled division can form tumours leading to development of cancer

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10
Q

what happens at fertilisation

A

two haploid gametes fuse together to form a zygote

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11
Q

what does the single cell at fertilisation develop into

A

a whole organism and external tissues such as the placenta

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12
Q

what does the zygote become after a few divisions

A

a blastocyst

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13
Q

what is a blastocyst

A

a cluster of dividing cells made by a fertilized egg

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14
Q

what does the blastocyst form

A

the outer layer of cells form the placenta and the inner layer of cells forms the embryo

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15
Q

what do the inner cells have the potential to do

A

to differentiate into any part of the new embryo but not the placenta

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16
Q

what happens as the embryo develops

A

some cells differentiate fully and are no longer classes as stem cells since they become specialised. others develop into specific forms of stem cells

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17
Q

what is potency

A

a stem cells ability to differentiate into different cell types

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18
Q

the greater the number of cell types it can differentiate into….

A

….the greater its potency

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19
Q

how do stem cells differ

A

depending on the types of cell they can turn into

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20
Q

what are the different categories of stem cells

A

totipotent, pluripotent, multipotent

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21
Q

what are totipotent stem cells

A

these stem cells can differentiate into any type of cell. a fertilised egg, or zygote and the 8 or 16 cells from its first mitotic divisions are totipotent cells which eventually form a whole organism. they can also differentiate into extra embyronic tissues like the amnion and the umbilicus

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22
Q

what are pluripotent stem cells

A

these stem cells can form all tissue types but not whole organisms. they are present in early embryos and are the origin of the different types of tissues within an organism

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23
Q

what are multipotent stem cells

A

these stem cells can only form a range of cells within a certain type of tissue. haematopoetic stem cells in bone marrow are multipotent because they give rise to the various types of blood cell. they lie dormant in body tissues throughout adult life

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24
Q

what do haematopoetic cells do

Study These Flashcards
A

found in bone marrow
they divide to replace lost or damaged blood cells

25
are haematopoetic cells totipotent, multipotent, or pluripotent
multipotent
26
what can haematopoetic stem cells differentiate into
white blood cells, red blood cells, platelets
27
list the types of stem cells with examples from increasing potency to decreasing potency
totipotent (zygote) pluripotent (embryonic stem cells) multipotent (adult stem cells) somatic (red blood cell)
28
how have multicellular organisms evolved from
unicellular organisms
29
what can groups of cells with different functions do
they can work together as one unit and can make use of resources more efficiently than single cells operating by themselves
30
what can cells in multicellular organisms do
they can specialise to take on different roles in tissues and organs
31
why do cells have different shapes and sizes
theyre adapted to different roles in an organism so have many shapes and sizes often containing different organelles
32
why are erythrocytes and neutrophils different even though they are both present in blood
they have different functions. when cells differentiate they become adapted to their specific role
33
what are all blood cells derived from
bone marrow
34
what is the job of erythrocytes and how are they adapted to do this
they transport oxygen around the body and are adapted by having a few organelle making more room for haemoglobin
35
what does the lack of organelles mean erythrocytes have
a short lifespan (120 days) so they need to be replaced constantly
36
how many erythrocytes do stem cells in bone marrow produce per day
approx. 3 billion per kg of body mass per day to keep up with the demand
37
how long do neutrophils in the immune system live for
6 hrs and colonies of stem cells produce 1.6 billion per kg per hour - this increases during infection
38
what are the sources of animal stem cells
embryonic and adult stem cells
39
what are embryonic stem cells
they are present at an early stage of embryo development and are totipotent. after 7 days, a blastocyst forms and cells are pluripotent. they remain in this state in the foetus until birth
40
what are adult stem cells
they are present throughout life after birth. they are found in specific areas such as bone marrow. they are multipotent but can be artificially triggered to become potent
41
where can stem cells be harvested from
umbilical cords of newborns
42
what is the advantage of harvesting stem cells from umbilical cords
there are plenty of umbilical cords and no invasive surgery is needed . they can be stored when needed. tissues cultured wont be rejected in a transplant to the umbilical cords owner
43
what are the sources of plant stem cells
in meristematic tisssue.
44
what type of stem cell is meristematic tissue
pluripotent - can grow throughout plants life
45
where are meristematic tissue found
wherever the plant is growing (tips of roots and shoots) they are located sandwiched between the phloem and xylem. cells from this region differentiate into cells in xylem and phloem tissue
46
when does vascular tissue grow
as the plants grow
47
give some potential uses of stem cells
stem cells transplanted into specific areas have the potential to treat certain diseases - heart disease --> repair muscle tissue damage in the heart - type 1 diabetes --> produce cells that make insulin - parkinsons disease --> drugs that delay the progress of the disease. (symptoms are cause by death of dopamine producing cells) - Alzheimers disease --> brain cells are destroyed so drugs are made to alleviate symptoms - Macular degeneration - finding ways to treat the blindness in elderly and diabetics - birth defects - spinal injuries
48
how are stem cells being used already
treatment of burns - stem cells grown on biodegradable meshes can produce new skin. quicker than taking graft from another part of the body drug trials - potential new drugs tested on cultures of stem cells before humans and animals developmental biology - study of the changes that occur as multicellular organisms grow and develop from a single cell and why things sometimes go wrong
49
where do the embryonic stem cells come from
donated from leftover embryos - involves destroying the embryo
50
how have the laws changed for using embryos
embryos are now created specifically in the lab
51
why are there objections to using embryos
people have religious and moral objections as they believe that life begins at conception so destruction of embryos is murder. there is also a lack of consensus as to whether the embryo itself has rights and who owns the genetic material being used for research
52
what can solve the debate of using embryos
using leftover umbilical cords instead
53
what is the issue with using umbilical cords
theyre multipotent
54
what else can be used instead of embryos and umbilical cords
adult stem cells
55
what is the issue with using adult stem cells
they dont divide as well as embryonic stem cells and are likely to cause mutations
56
what is being developed to solve all these issues
artificially transforming tissue stem cells to pluripotent cells.
57
what are induced pluripotent cells
adult stem cells that are genetically modified to act like embryonic stem cells so are pluripotent
58
does using plant stem cells raise any ethical concerns
no

2.1.6 cell division, cell diversity and cellular organisation (6 decks)

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