Stem cells + plant stem cells Flashcards
what are the features of a stem cell
undifferentiated cells that continually divide and become more specialised
give rise to specialised cells
capable of self renewal
no limit to division
can be:
totipotent
pluripotent
multipotent
features of a totipotent stem cell
give rise to every specialised cell in the body (all 216)
undifferentiated/unspecialised cells
can keep dividing
form 8 embryo cell
all genes are switched on
features of pluripotent stem cells
give rise to most cells in the specialised cells in the body (except totipotent embryonic cells)
undifferentiated/unspecialised cells
no limit do division
from blastocyst or umbilical cord blood
some genes switched off
features of multipotent stem cells
undifferentiated/unspecialised cells
give rise to only those of closely related family
found from birth onward (e.g. bone marrow)
many genes switched off as cells have become differentiated
where are totipotent stem cells found
from the zygote
until the 8 cell embryo
all cells are totipotent since they have the potential to develop into all body cells
where are pluripotent stem cells found
5 days after fertilisation the blastocyte forms
outer blastocyte cell layer will form the placenta
inner cell mass will eventually form the embryo
source of pluripotent stem cells till day 16
where are multipotent stem cells found
after birth
found in bone marrow and body tissue
how do cells become specialised
some genes become switched on and some become switched off
switched on genes are transcribed and translated into proteins which are then used for specific function of that cell
what potency do plant cells remain there whole life and why is this important
remain totipotent
important since it allows plants to be grown from a fragment (explant) of a leaf, stem, root or from a single cell by plant tissue culture
how does plant tissue culture work
explant (fragment) of plant tissue is placed on sterile agar which contains growth regulators and nutrients using an aseptic technique
explants are then placed under a light bank for around 4 week
cells then differentiate to form a whole new plant
new plant is a genetically identical clone of the original plant
what are plant tissue cultures used for
improve plant and food crop species (e.g. create disease resistant plants)
produce increased quantities of plant chemicals used in drugs
produce commercial plants that are difficult to grow from seeds
conserve endangered plants
