Stem cells lecture Flashcards
What are types of cell division?
Symmetric, asymmetric, self-renewing
How does asymmetric division in caulobacter work?
Cells follow a chemotactic gradient (halt growth on nutrient starvation and swim to new nutrient-rich location)
Parent cell is stalked and adheres to surfaces
Divides into 1x stalked and 1x swarmer cell (flagellated and mobile)
Parent cell is polarised before division with emergence of flagella and chemotactic pilli at the end opposite the stalk
Thus on division daughter cells are different
How does division in persister bacteria work?
Persister bacteria= normally occuring phenotypic variants that result from gene activation putting the cell in a slow-growing state like quiescence
They evade the environmental stress of antibiotics
Persister behaviour is lost after a few divisions and progeny become sensitive to original stress
Progeny switch between persister and normal growth by chance (stochastic)
What is key property of stem cells?
They can self-renew indefinitely or produce progeny that differentiate
What are multipotent stem cells?
Can generate multiple types of differentiated cells eg. blood stem cells
What are unipotent stem cell? (give an example)
Give rise to one cell type eg. epidermal stem cell
What are adult stem cells?
Stem cells responsible for tissue maintenance and regeneration
What are pluripotent stem cells?
Embryonic stem cells, can self-renew indefinitely and maintain capacity to generate all cell type in adult
What is a totipotent stem cell?
Fertilised egg, gives rise to all cells in organism AND extra-embryonic tissue that sustains embryo development
Draw diagram of haemopoetic system
(see notes for diagram)
Each cell type created by step-wise restriction of differential potential eventually making unipotent progenitors, then maturation to fully differentiated functional blood cells
What is blood system’s daily cell turnover?
10^11 cells
What are some other stem cell systems with regular turnover?
Epidermis (skin) gut epithelium, stomach, small intestine, sperm
When are other stem cells activated?
In injury/development
On injury what happens to a mouse HSC, and what happens when it recovers?
Gets activated and proliferates once every 36 days (normally 145 days)
Reverts to quiescence when steady state restored
Describe HSC quiescent vs. active
Q: low metabolic activity and protein production, resident in specific bone marrow region (niche) distant from blood cells
A: moves away from niche, activates energy and protein production, cycles more often
