stem cells Flashcards
define stem cell
undifferentiated cell with the potential to differentiate into a variety of the specialised cell types of the organism
define undifferentiated
unspecialised cell originating from mitosis or meiosis
define totipotent
stem cells capable of dividing to produce all cell types to form a whole organism
define pluripotent
stem cells capable of dividing to produce all cell types but not extraembryonic membranes so not a whole organism
define multipotent
stem cells capable of dividing to produce several cell types
what is a embryonic stem cell
another name for a pluripotent stem cell
what is an adult stem cell
another name for a multipotent stem cell
describe the characteristic abilities of stem cells compared to specialised cells.
- stem cells are able to undergo cell division indefinitely, specialised cells are not able to undergo cell division at all
- stem cells can differentiate into other cell types, specialised cells can’t
explain the importance of stem cells
source of new cells for growth, development and tissue repair
why must stem cell activity be carefully controlled?
- not dividing fast enough = tissues not efficiently replaced = ageing
- dividing too quickly without control = tumors which could lead to cancer
state the 3 types of stem cell and give examples of where they occur in animals
- totipotent - zygote + the 8/16 cells from its first few mitotic divisions
- pluripotent (embryonic stem cells) - early embryos
- multipotent (adult stem cells) - bone marrow
state where stem cells occur in plants and state which potency they have
- found in meristematic tissue (meristems) - wherever growth is occurring in plants
- also found between xylem and phloem - vascular cambium
- pluripotent
outline how a cell becomes specialised
- stem cells in the cell cycle replicate indefinitely until
- specific genes within stem cell activate so it differentiates by expressing features required for its function + becomes specialised
- cell has entered G0 once specialised and cannot divide anymore
explain why it is important for erythrocytes to be constantly produced.
- essential for transport of oxygen around the body
- short lifespan (120 days) so they need to be replaced constantly
explain why it is important for neutrophils to be constantly produced
- important role in immune system
- only live about 6 hours so must constantly be replaced (even more produced when infected)
outline how xylem vessels and phloem sieve tubes are produced from meristems
- meristematic tissue located between xylem and phloem tissues - vascular cambium
- cells originating from this region differentiate into diff cells present in xylem and phloem tissues
state 7 diseases that stem cells have the potential to treat
- heart disease
- type 1 diabetes
- parkinson’s disease
- alzheimer’s disease
- macular degeneration
- birth defects
- spinal injuries
suggest how stem cells could be used to treat heart disease
stem cells repair damage in muscle tissue in heart caused by heart attack
suggest how stem cells could be used to treat type 1 diabetes
- replace insulin producing cells in pancreas that were destroyed by body’s own immune system
suggest how stem cells could be used to treat parkinson’s disease
replace dead dopamine-producing cells in brain
suggest how stem cells could be used to treat Alzheimer’s disease
replace brain cells destroyed due to buildup of abnormal proteins
suggest how stem cells could be used to treat macular degeneration
replacing cells in retina to prevent blindness in elderly and diabetics
suggest how stem cells could be used to treat spinal injuries
replacing damaged spinal cords using stem cell implants
suggest how stem cells could be used to treat burns
- stem cells grown on biodegradable meshes can produce new skin for burn patients
- quicker than taking graft from another part of body
state two ways in which stem cells may be useful in research.
- drug trials
- developmental biology
describe how stem cells may be useful in drug trials
new drugs can be tested on cultures of stem cells before being tested on animals and humans
describe how stem cells may be useful in developmental biology
because they can divide indefinitely + differentiate into various types of cells they can be used to study changes that occur as multicellular organisms grow + develop from a single cell + why things go wrong
Describe arguments for the use of embryonic stem cells for research and medicine.
- allow us to find treatments for incurable diseases
- allow us to study developmental biology more closely
- embryos used were donated from those left over after fertility treatment - would have been discarded anyway
describe arguments against the use of embryonic stem cells for research and medicine.
- “life begins at conceptions and destruction of embryos is murder”
- experiments do not guarantee any benefits to human life
Define induced pluripotent stem cell
adult stem cells that have been genetically modified to act like embryonic stem cells/pluripotent stem cells
explain why induced pluripotent stem cells may be useful in research and medicine
- could be useful replacement for actually harvesting embryonic stem cells - not as controversial
- can readily be made in a lab
