Stem Cells

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  • Created by: Hindleyc
  • Created on: 12-04-19 13:48
What do all cells contain
the same genes
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What does this mean every cell is capable of
everything the body can produce
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What are some genes
permanently expressed (switched on) in all cells
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What are other genes
permanently not expressed (Switched off)
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What isn't every cell using
every gene in genome= silent- not expressed wound up tight so not transcribed into mRNA= no protein
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What do most body cells only do
express a few of their genes so can Carry out a limited set of functions
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What are these cells
specialised (differentiated)
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What do organisms develop from
single fertilised egg which has the ability to give rise to all types of cell
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In animals what are specialised cells
irreversibly differentiated so they and their daughter cells will keep their specialisation and cannot become any other kind of cell
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However what are there
few cells that remain undifferentiated and so can become any type of cells called stem cells
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What do stem cells have
no limit on the number of times they can divide
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What 2 key properties do they possess
Potency- stem cells have potential to differentiate into specialised cell types (range) and immortality- stem cells can divide indefinitely
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4 types of stem cells
totipotent, pluripotent, multipotent, unipotent
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What are totipotent stem cells
Everything-cells which can mature into any body cell (divide and reproduce into any type of body cell)
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Where are they found
Early embryo and can differentiate into any type of cell that makes up the body
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what are the examples
all body cells formed from a zygote follows that zygote is totipotent (fertilised egg cell)
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As zygote divides and matures what happens
its cells develop into slightly more specialised called pluripotent stem cells
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What do they have the power to
make up whole organism
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What do the cells occur for
only a limited time in early mammalian embryos
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Also cells that support the
embryos eg placenta
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During development what can cells do
can translate only part of their DNA resulting in cell specialisation
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What are pluripotent
Many- found in embryos and can differentiate into almost any type of cell eg embryonic stem cells and fetal stem cells
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What do they have the power to
differentiate into any of specialised cells of body but not the placenta
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What don't they have the power to do
generate whole new individual
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after a few days of development what happesn
human embryo to blastocyst (hollow ball) to inner cell mass containing pluripotent
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What can they do
Divide in unlimited numbers and can be used in treating human disorders
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What are multipoint cells
few- found in adults and can differentiate into a limited number of specialised cells, usually develop into cells of a particular type
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eg
stems cells in bone marrow and can produce any type of blood cell, adult stem cells and umbilical cord blood stem cells
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In adults what contain them
some tissue (brain and bone marrow)
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What are unipotent
one- can only diff into a single type of cell derived from multipotent stem cells and are made in adult tissue eg in heart formation of cardiomyoctes cells that diff into new heart muscle cells
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Where are multipotent and unipotent found
in mature mammals and can divide to form a limited number of different cell types
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What did discovery of stem cells immediately lead to
suggestions that they could be used clinically
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idea
transplant tissue grown from stem cells into a patient where it would grow and replace damaged tissue eg hear and muscle cells, skeletal muscle cells, B cells of pancreas
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Using own stem cells=
no risk of rejection- no foreign antigens unlike conventional transplant
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What does it have potential for
long term cure eg cancer
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What else is it only
single treatment
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What do embryonic stem cells have
Greatest potency
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How are they grown
in vitro from human embryos (blastocysts) created by in vitro fertilisation
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What are these embryos
made to help infertile couples reproduce but any spare embryos no longer needed for reproduction can be used to create stem cells with the informed consent of the donor couple
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What are these stem cells
pluripotent so can be differentiated into a wide variety of different cell types for clinical use
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However was does there remain
debate about whether it is ethical to use human embryos for this purpose
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What has embryonic stem cell research been
banned across Europe by the European parliament although UK government does allow such research in the UK
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In the UK up to how old can human embryos be used in stem cell research
up to 14 days old
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What surround use of stem cells
much controversy- particularly embryonic stem cells and there are strict regulations controlling their use
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What is therefore an attractive prospect
alternative sources of stem cells
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What ar induced pluripotent stem cells (iPSCs)
normal specialised adult cells that have been genetically reprogrammed to become undifferentiated pluripotent stem cells
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What are they
very new development, and still at research stage but they may solve some of the problems of both adult and embryo stem cells
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How can they be produced
from adult somatic cells using appropriate protein transcription factors
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Where are adult stem cells extracted from
certain tissues of the body
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What is thought
most organs and tissues contain small number of undifferentiated stem cells which body uses for repair
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The tissues where stem cells have been found include
brain, bone marrow, blood vessel, muscle, skin, heart, gut and liver
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What does the use of these cells have
no ethical issues and no problems of rejection if the stem cells are taken from the patients own body
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however
however they are difficult to find and difficult to grow in culture and they are only multipotent
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Card 2

Front

What does this mean every cell is capable of

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everything the body can produce

Card 3

Front

What are some genes

Back

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Card 4

Front

What are other genes

Back

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Card 5

Front

What isn't every cell using

Back

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