B2.3 Cell Specialisation

Properties of stem cells

- can repeatedly divided
- they can stay undifferentiatied or differentiated into specific cells

Examples of adaptation to increase SA:volume: KIDNEY

- Kidneys has long thin tubles that filter out waste molecues and reabsorbs glucose, mineral ions etc.

- these tubes have invaginations to increase surface area

Examples of adaptation to increase SA:volume: Red blood cells

- the have a bioconcave disc shape that provides them a large SA:vol ratio to quickly load and unload oxygen

Adaptation of type I and II pneumocytes

PNEUMOCYTES: cells (TYPE 1 & TYPE 2) that line the alveoli and comprise of the majority of the inner surface of the lungs.

1) Type 1 pneumocytes (95%)

- thin cells forquick diffusion of gases in and out of vessels

2) Type 2 pneumocytes (5%)

- Produces a liquid called surfactant to stop aveolar wall from sticking (reduce surface tension)

Adaptation of cardiac muscle cells & striated muscle fibres

Adaptation of sperm and egg cells

Differentiation

- Differentiation is the process to developing different highly specialised cells from initial embro cells
- Differentiation happens when different genes are activated or expressed to create different cell types

production of unspecialiased cells

- Signalling chemicals (morphogens). determine which genes will be expressed

- The cell’s position in the embryo determines the concentration of these chemicals and which specialized cell type the cell will become.

Different stem cells

Toti-potent: can become any cell type (including placenta)
Pluri-potent: can become any cell type( excluding placenta)
multi-potent: can only become related cell types

Cell Size as an aspect of specilialisation (Rank the following)
(sperm, striated muscle fibres, neurons/nerve cells, Egg/ovum, red blood cells)

specific measurements are not to be memorised

acrynom: RSESN (race season ends soon noooo)

Surface area to volume ratio for cells

- the bigger the cell, the smaller the surface area-to- volume ratio
- increasing surface area of a cell increases the exchange of material in and out of the cell.
- The bigger the SA: vol ratio the more efficient the rate of exchange of material in and out of the cell
- the SA:volume ratio is important in how efficient a cell is at getting rid of waste

what happens to the surface area-to-volume ratio when cell divides?

the volume remains the same however surface area increase---hence, larger SA:volume ratio

Adaptation to increase SA:volume ratio of cells (traits of cells)

- being thin and flat

- being folded or invaginated

- having villi and microvilli