stem cells Flashcards
what is a stem cell?
an undifferentiated cell which can divide to produce more cells of the same type or differentiate to form other cells
where are stem cells found in?
-bone marrow
-meristems
-embryos
two types of stem cells found in animals
-embryonic
-adult
describe how embryonic stem cells are formed?
- A sperm cell fertilises an egg cell and they form a zygote
- The cell divides mitosis to form a ball of cells called an embryo
- The cells in the embryo are known as embryonic stem cells
what can adult stem cells differentiate to form?
-cells in the blood (red & white blood cells, platelets)
difference between adult and embryonic stem cells
embryonic stem cells can differentiate into any type of cell unlike adult stem cells
meristems
plant tissues that is continually growing and contains stem cells
where are meristems found?
tips of shoots
tips of roots
what are meristems used for?
-produce plant clones quickly and cheaply for research
-grow more plants of rare species to prevent them from going extinct
-used to grow crops of identical plants if they have an ideal characteristic
when can stem cells in meristems differentiate?
throughout the plant’s life-anytime
what can meristems differentiate into?
any type of plant cell
uses of embryonic stem cells
-replace faulty cells
-treat conditions such as paralysis and diabetes as they divide to replicate damaged cells
what is paralysis?
when nerve cells are damaged
stages of stem cell treatment
- extract embryonic stem cells from embryos
- grow them in a laboratory
- stimulate them to differentiate into whichever specialised cells we want
- give them to patient to replace faulty cells
stages of therapeutic cloning
- nucleus taken out of human egg cell
- nucleus from a patient’s cell put into the egg cell
- egg cell stimulated to divide and develop into an embryo
- stem cells taken from the embryo after 4-5 days
- stem cells grow in a container of warm nutrients
- stem cells treated to develop into required cell types for a patient
advantage of therapeutic cloning
the body won’t reject the cells
disadvantages of using embryonic cells in stem cell therapy
-risk of rejection
-stem cells in limited supply
-ethical issues as you are destroying a potential human life
advantages of adult cells
-won’t cause rejection as taken directly from patient
-taken from patient so not in limited supply
disadvantages of adult cells
-have to be extracted from bone marrow which is painful
-can only differentiate into a few types
-could transfer infections
risks of stem cells in medicine
-could be infected with a virus in the lab which could infect the patient and make them worse
-chance of dividing uncontrollably and develop into a tumour once transplanted
uses of adult cells
differentiate into several cell types to replace dead or damaged tissues
what is therapeutic cloning?
a cloning method where an embryo is produced with the same genetic makeup as the patient, stem cell will not be rejected so can be used to treat conditions
what is the function of the meristem in the growth of a plant?
- meristem cells are undifferentiated
- meristem cells divide
- by mitosis
- to give rise to new tissues
