stem cells Flashcards
what is differentiation
the process of a cell becoming specialised
what are stem cells
undifferentiated cells that are not adapted to any particular function and have the potential to differentiate to become any one of the range of specialised cell types in the organism
what happens to stem cells once they become specialised
- they lose the ability to divide and enter the G0 phase of the cell cycle
what is potency
a stem cell’s ability to differentiate into different cell types
totipotent
- can differentiate into any type of cell (fertilised egg, first 8/16 cells from mitotic divisions)
- can differentiate into extra embryonic tissues
pluripotent
- can form all tissue types but not whole organisms
- present in early embryos and are the origin of the different types of tissue in an organism
multipotent
- can only form a range of cells within a certain type of tissue
- (e.g. haematopoetic stem cells in bone marrow differentiate into blood cells
name for red blood cells
erythrocytes
name for white blood cells
neutrophils
where are all blood cells derived from
stem cells in the bone marrow
role of erythrocytes
- transport of oxygen around the body
- maximise their oxygen carrying capacity by having few organelles to make room for haemoglobin
- biconcave disc shape provides large surface area for gas exchange
- no nucleus
- short lifespan of 120 days so replaced constantly
role of neutrophils
- immune system
- live for 6 hours
- flexible shape allows them to engulf foreign particles
- many lysosomes contain digestive enzymes to break down the engulfed particles
embryonic stem cells
- present in early stage of embryo development
- totipotent
- after 7 days, blastoclyst is formed which is pluripotent
tissue (adult) stem cells
- present throughout life from birth
- found in bone marrow
- harvested from umbilical cord
- multipotent
source of plant stem cells
- meristematic tissue
- found where growth occurs (tips of roots or shoots)
- found in vascular cambium in between xylem and phloem
- pluripotent
uses of stem cells
- heart disease
- type 1 diabetes
- Parkinson’s disease
- Alzheimer’s disease
- macular degeneration
- birth defects
- spinal injuries
- treatment of burns
- drug trials
- developmental biology