6.5 stem cells

what are stem cells

• undifferentiated cells from mitosis or meiosis

• not adapted to a particular function

• have potential to differentiate to become specialised

what is G0 phase for stem cells

when stem cells become specialised and lose ability to undergo cell division

how are tumours related to stem cells

uncontrolled division form masses of cells which can lead to development of cancer

what does potency mean

stem cells ability to differentiate into different cell types

what does totipotent mean

• can differentiate into any type of cell

• can also differentiate into extra-embryonic tissues (amnion and umbilicus)

examples of totipotent cells

fertilised egg, zygote, 8 or 16 cells from first few mitotic divisions

what does pluripotent mean

can form all tissue types but not whole organisms

examples of pluripotent cells

early embryos

what are multipotent cells

cells that can only form a range of cells within a certain type of tissue

examples of multipotent cells

haematopoetic stem cells in bone marrow - only creates types of blood cell

lifespan of RBC

around 120 days, need to be replaced constantly, bone marrow produce 3 billion per kg of body mass per day

life span of neutrophils

6 hours, bone marrow produce 1.6 billion per kg of body mass per hour, inc during infection

what are two sources of animal stem cells

• embryonic

• tissue (adult)

how potent are embryonic stem cells

totipotent

when does the potency of embryonic stem cells change

after a blastocyst is formed, cells are now pluripotent and remain until birth

where are adult stem cells found

bone marrow

what potency are adult stem cells

multipotent, but can be artificially triggered to become pluripotent

where can stem cells be harvested from newborn babies

umbilical cord

why would you use stem cells form umbillical cord

if needed in the future, stem cells will not be rejected in a transplant

where are stem cells found in plants

meristematic tissue

where are meristematic tissue found

root tips and between phloem and xylem (vascular cambium)

what do stem cells in vascular cambium differentiate into

different cells present in xylem and phloem tissues

what potency are plant stem cells

pluripotent

how can stem cells be used for heart disease

replace damaged muscle tissue in the heart

how can stem cells be used for type 1 diabetes

regenerate insulin-producing cells in the pancreas

how can stem cells be used for parkinson’s disease

caused by death of dopamine-producing cells in brain, delay progess of disease

how can stem cells be used for alzheimers disease

brain cells destroyed as a result of the build up of abnormal proteins, drugs alleviate symptoms

how can stem cells be used for macular degeneration

researching into use of stem cells to combat blindness in the elderly and diabetics

how can stem cells be used for birth defects

reversed birth defects in mice

how can stem cells be used for spinal injuries

restore some movement to hind limbs of rats with damaged spinal cords

how can stem cells be used for burns

stem cells grown on biodegradable meshes can produce new skin

how can stem cells be used for drug trials

potential new drugs can be tested on cultures of stem cells before being tested on animals and humans

how can stem cells be used for developmental biology

study of the changes that occur as multicellular organisms grow and develop from a single cell, and why some things go wrong

what are the ethical problems with embryonic stem cells

removal of embryonic stem cells normally result in destruction of embryos, some believe that this is taking a potential life and therefore murder. lack of consent from embryo

what are induced pluripotent stem cells iPSCs

adult stem cells that have been genetically modified to act like embryonic stem cells