Week 1 Cells and Tissue

Question 1

Eyepiece, Objective

How is total magnification calculated?

Answer 1

Total magnification = eyepiece magnification x objective lens magnification.

Question 2

What is the maximum resolution of a light microscope?

Answer 2

200nm

Question 3

How do you view dead cells under a light microscope?

Answer 3

• Make tissue rigid to allow sectioning by fixing in formalin and embedding tissue in paraffin wax or freezing tissue in a block
• Use microtome to cut 1-10microm
  sections (typically width of 1 cell).

Question 4

What is a chromogenic reaction?

Answer 4

A colour changing reaction can be used in immunohistochemistry.

Question 5

FIxing cells would kill them.

How would you view living cells under a light microscope?

Answer 5

• Use phase contrast or to change the wavelength of light - creates contrast by changing amplitude.
  OR
• Differential interference contrast (DIC) bending light waves so that it falls on the cell at different angles, creating a shadow to introduce contrast.

Question 6

What does cryoelectron microscopy involve?

Answer 6

Rapidly freezing samples to cryogenic temperatures (between -150oC and absolute zero) - sample forms “glass-like” state, no ice crystals.

Question 7

What is Osteogenesis Imperfecta?

Answer 7

• Collagen disorder, disease of the ECM.
• Deficiency in collagen 1, bones don’t form properly.

Question 8

What is scurvy?

Answer 8

There is regular degradation and replacement of collagen. Due to vitamin C deficiency, replacement of collagen fails, leading to fragile blood vessels and poor wound healing.

Question 9

What is Marfan’s Syndrome?

Answer 9

• Connective tissue disorder, caused by mutation in gene to produce fibrillin-1 protein, leading to incorrectly synthesised elastin.
• Widespread effects on body including potential rupture of aorta and other skeletal and joint abnormalities.

Question 10

What is Cutis Laxa?

Answer 10

• Skin lacks elasticity, appears look and wrinkly, mutation in elastin gene.

Question 11

What is Ehler’s Danlos Syndrome?

Answer 11

Connective tissue disorder caused by various mutations including gene coding for Tenascin X (glycoprotein)
Common symptoms of joint hypermobility, skin hyperextensibility, and tissue fragility.

Question 12

What is Glanzmann’s Disease?

Answer 12

Inherited blood clotting disorder due to impaired function of platelets. Symptoms of abnormal bleeding.