biology 6.3 - stem cells and differentiation

Where are stem cells found in plant cells?

In the meristem and in the vascular cambium (between phloem + xylem so divide and differentiate to form xylem vessels and phloem sieve tubes

Stem cells are being used to research developmental biology. What is developmental biology?

How organisms grow and develop

What happens once cells have differentiated?

They have a specific function and their structure is adapted to performs this function

What are neutrophils’ (animal cell) function and how are they adapted to carry out this function?

To engulf foreign particles and pathogens and produce antibodies

Flexible shape to engulf and lots of lysosomes in cytoplasm to break down engulfed particles / pathogens

What are erythrocytes’ (animal cell) function and how are they adapted to carry out this function?

To carry oxygen

Biconcave shape to maximise surface area which maximises gas exchange, no nucleus so more room for heamolglobin so more oxygen carried

What are epithelial cells’ (animal cell) function and how are they adapted to carry out this function?

To cover organ’ surfaces

The cells are joined by interlinking cell membranes and a membrane at their base

Ciliates epithelia - in airways, have cilia

Squamous epithelia - in lungs, very thin to allow efficient gas exchange

What are sperm cells’ (animal cell) function and how are they adapted to carry out this function?

To fuse with an egg cell

Have a flagellum and lots of mitochondria to help it reach the egg, the acrosome contains digestive enzymes to the sperm cells, can enter the egg

What is the palisade mesophyll’s (plant cell) function and how is it adapted to carry out this function?

To perform photosynthesis

Lots of chloroplasts, thin walls for gas exchange

What are root hair cells’ (plant cell) function and how are they adapted to carry out this function?

To perform active transport

High surface area for diffusion, thin and permeable cell wall so water and ions can enter, extra mitochondria for active transport

What are guard cells’ (plant cell) function and how are they adapted to carry out this function?

To open and close the stomata

Found in pairs, when it is light they take up water to become turgid which makes the thin outer wall and thickened inner wall bend outwards to open the stomata so gas exchange can occur