Stem cells Flashcards
what are stem cells
undifferentiated cells which can keep dividing to give rise to other cell types
definition of multipotent cells
are differentiated cells that can specialise into many different types of cells
definition of pluripotent cells
can give rise to many types of specialised cells, but not all cell types (such as placental cells)
definition of totipotent cells
undifferentiated cells that can divide and give rise to any type of specialised cells
what is a blastocyst
-a hollow ball of 50 or so cells
-a type of pluripotent stem cell
-the outer blastocyst cell layer goes on to form the placenta
-the inner 50 cells form the tissues of the developing embryo
definition of explant, callus and plantlet
explant- small piece of plant tissue transferred to growth medium
callus-a mass of undifferentiated cells
plantlet-young genetically identical plants
how to do tissue culture of plants
explants are taken from plants
-they are sterilised
-then placed on an agar medium with nutrients and growth hormones
-the cells divide to form a mass of undifferentiated cells called a callus
-the embryos develop into plantlets that are gentically identical clones
embryonic stem cells- where? type? use?
found in early stage embryos
pluripotent-can develop into almost any cell type in the body
uses- Due to their ability to differentiate into almost any cell type, embryonic stem cells have huge potential in the therapeutic treatment of many diseases
use is ethically debated
adult stem cells - where? type? use? risks?
found in bone marrow and brain
multipotent-can differentiate into a limited range of cell types
use- repair and maintaining tissues
risks- there is a chance that the cells used are rejected by the patient’s immune system if donor stem cells used
induced pluripotent stem cells
created by reprogramming adult cells into a pluripotent state
functions like embryonic stem cells w/o ethical concerns
useful for disease modelling and dry testing
therapeutically cloned stem cells
created using somatic cell nuclear transfer
can generate genetically matched stem cells for patients
used to repair damaged tissues
advantages and disadvantages of embryonic stem cells
+ can become any cell type
- ethical concerns, risk of immune rejection
advantages and disadvantages of tissue/adult stem cells
+ no ethical concerns and taken from the patient’s own body
-limited differentiation ability, harder to obtain
risks of using stem cells
- stem cells cultured in a lab could become infected with a virus
- low numbers of stem cell donors
what did the acetabularia experiment find
The nucleus controls cell development using mRNA as a messenger molecule
what did the dolly sheep experiment find
All the genetic info for making a complete organism is present in every cell( except haploid and red blood cells)
what did david and sargent find
As cells specialise, more genes are active and more mRNA is produced.
How does differential gene expression happen?
