Despair

Question 1

What are lamellipodia?

Answer 1

Micro-filament (actin) based membrane protrusions that help the cell to move.
(Found in keratinocytes and help during reepithelialisation)

Question 2

What are filopodia?

Answer 2

Very small spikes of micro-filament based protrusions of the plasma membrane involved in cell motility.
(Found in growth cone of neurons, epithelial sheets and fibroblasts)

Question 3

What are lipid rafts in the plasma membrane?

Answer 3

cholesterol-rich domains that compartmentalise function by concentrating molecules, eg act as ‘signalling platforms’ by concentrating signalling receptors

Question 4

What is the glycocalyx?

Answer 4

a layer of carbohydrate that covers cells. Many functions including cell recognition. Cells lining the gut have a thick glycocalyx where digestive enzymes reside

Question 5

Describe molecular organisation within the cell membrane.

Answer 5

• Membrane anchored and transmembrane proteins
• Phospholipid types (phosphatidylcholine usually outer layer, phosphatidylserine usually on the inner layer of the bilayer)
• cholesterol

Question 6

What are the 4 compartments of the mitochondrion?

Answer 6

1. Outer membrane (has selective permeability e.g. pyruvate)
2. Inner membrane folded into cristae (ETC takes place here)
3. Matrix (enzymes for citric acid/TCA cycle)
4. Intermembrane space (important in the ETC and enzymatic action, location of cytochrome C)

Question 7

What are the usual stages of tissue processing for histology?

Answer 7

1. Fixation
2. Embedding
3. Sectioning
4. Staining

Question 8

Does haemotoxylin or eosin stain the nucleus?

Answer 8

Haemotoxylin as it is basic and the nucleus is acidic/basophilic.

Question 9

When would PAS be used in staining?

Answer 9

• for complex carbohydrates and glycogen
• a tissue stained with PAS is known as PAS+
• e.g. the liver is PAS+ because it has lots of glycogen
• also stains basement membranes, mucus and brush borders of intestines
• stains magenta