Histochemistry

Question 1

If the bacteria being studied in vitro is gram negative, what colour will the bacteria ‘hold’? Also, what is the name of that colour?

Answer 1

Gram-negative bacteria, will ‘hold’ onto a red dye called safranin.

Question 2

If the bacteria being stained is gram-positive, what is the name, and what colour will the bacteria ‘hold’ ?

Answer 2

If the bacteria is gram-positive it will hold onto a purple stain called crystal violet.

Question 3

Give 2 other techniques used in histochemistry.

Answer 3

Harmatoxylin binds to negatively charged molecules such as those in phosphate groups and so stains nuclei acids; used to visualise nuclei.

Eosin binds to positively charged molecules, including many cytosolic proteins and so is used to stain the cytosol.