Cell Differentiation

Question 1

Important features of Stem Cells:

Answer 1

1) Unspecialised
2) Can differentiate (see semester 2)
3) Self-renewal (i.e. regenerate / lifelong)

Question 2

Stem cells have an unlimited capacity to…

Answer 2

…self-renew and produce ‘differentiated’ cells of various types

Question 3

The ‘progenitor cells’, midway down have…

Answer 3

…limited capacity to self-renew and
and differentiate

Question 4

Terminally differentiated cells do not…

Answer 4

…self renew and do not differentiate

Question 5

Totipotent stem cells are known as the…

Answer 5

…‘ULTIMATE’ stem cell

Question 6

Totipotent stem cells have the ability to…

Answer 6

…differentiate into ALL body cell
types, including cells that make
the placenta

Question 7

Pluripotent stem cells can differentiate into the…

Answer 7

…3 ‘germ’ layers of the human body

Question 8

Multipotent stem cells can differentiate into…

Answer 8

… limited cell types

Question 9

The 3 germ layers of pluripotent stem cells:

Answer 9

Ectodermal, Mesodermal and Endodermal

Question 10

Ectoderm will form…

Answer 10

… epidermal layer of skin

Question 11

Endoderm will form…

Answer 11

…the lining of the gut, the liver, and the lungs.

Question 12

The neural ectoderm will form …

Answer 12

…the nervous system

Question 13

The gray crescent is the site where…

Answer 13

… major cell movement will begin.

Question 14

Mesoderm will form…

Answer 14

…muscle, bone, kidneys, blood, gonads, and connective tissue.

Question 15

Stem cells are NOT named after their characteristics, but…

Answer 15

… the type of tissue that they can differentiate into

Question 16

Within multicellular organisms, tissues are…

Answer 16

…collections of different types of specialised cells that function together

Question 17

The evolution of multicellular life corresponded with…

Answer 17

…an increase in atmospheric oxygen levels ~1.8 billion years ago

Question 18

Cells divide by…

Answer 18

…binary division i.e., one cell produces two offspring cells

Question 19

For differentiation one of the offspring cells must retain…

Answer 19

…phenotypic plasticity and self-renewal properties, whilst the other must
differentiate along a given lineage

Question 20

The niche is central for…

Answer 20

…cellular differentiation & maintaining stem cells

Question 21

Whats the stem cell niche?

Answer 21

The niche is a special microenvironment that provides physical signals.

1) Cell-cell contact
2) Cell matrix interactions
3) Mechanical
4) Biochemical (growth factors, hormones)

Question 22

In vitro studies formally show that asymmetric cell division is dependent on…

Answer 22

…mechanical cues, even in the absence of biochemical signals.

Question 23

Cell adhesion molecules are expressed on the…

Answer 23

…plasma membrane.

Question 24

The extracellular domain interacts with …

Answer 24

…the extracellular matrix i.e., collagen

Question 25

The intracellular domain interacts with…

Answer 25

…the cytoskeleton

Question 26

The mechanical interaction between the extracellular matrix and the cell cytoskeleton allows the cell to…

Answer 26

…exert traction forces

Question 27

The mechanical interaction between the extracellular matrix and the cell cytoskeleton allows the cell to exert traction forces.

These forces are transmitted
through…

Answer 27

…intracellular pathways to the nucleus in a process called ‘mechanotransduction’

Question 28

The mechanical interaction between the extracellular matrix and the
cell cytoskeleton allows the cell to exert traction forces

These forces are transmitted
through intracellular pathways
to the nucleus in a process
called ‘mechanotransduction’

This results is a pattern of …

Answer 28

…specific gene expression
changes in the cell

Question 29

Integrins anchor…

Answer 29

…progenitor cells

Question 30

Integrins anchor progenitor cells permitting…

Answer 30

… differentiation

Question 31

Cadherins anchor…

Answer 31

…the stem cells to niche cells and ECM permitting self-renewal.

Question 32

Cadherin proteins hold…

Answer 32

…stem cells in the niche and provide mechanical signals.

Question 33

Progenitor cells (differentiating)
rely on…

Answer 33

…integrin proteins for
mechanotransduction

Question 34

What are isotropic forces?

Answer 34

pulling & stretching. Pull the cytoskeleton equally.

Question 35

In vitro models demonstrate that ‘isotropic forces’ - pulling & stretching
of the cytoskeleton along with differential forces exerted by the ECM /
niche cells, plus the partial pressure of oxygen initiate…

Answer 35

…differentiation

Question 36

Anisotropic forces pull…

Answer 36

…the cytoskeleton unequally, causing
the cell to elongate.

• Forces are also applied back from the
  niche

Question 37

Using progenitor cells, the effect of isotropic forces (soft) on cell
differentiation can be appreciated by …

Answer 37

…in vitro modelling

Question 38

Using progenitor cells, the effect of isotropic forces (soft) on cell
differentiation can be appreciated by in vitro modelling

In this very clean experimental system, the cells on the left will form …

Answer 38

…cardiac muscle cells (cardiomyocytes)

Question 39

Using progenitor cells, the effect of isotropic forces (soft) on cell
differentiation can be appreciated by in vitro modelling

In this very clean experimental system, the cells on the left will form
cardiac muscle cells (cardiomyocytes), whereas the cells on the right
will form…

Answer 39

…neuronal cells

Question 40

Using progenitor cells, the effect of isotropic forces (soft) on cell
differentiation can be appreciated by in vitro modelling

In this very clean experimental system, the cells on the left will form
cardiac muscle cells (cardiomyocytes), whereas the cells on the right
will form neuronal cells. In both cases…

Answer 40

…differentiation is altered.

• You will notice the ‘random’ dendrite formation in the neuronal cells.

Question 41

slide 19, 20, 21, 22, 23.