How do you stain a yeast cell?

The staining technique of Gutstein (4) provides a convenient means for staining yeast as an aid in its microscopic examination. The solutions required are: 1% solution of methylene blue in distilled water 5% solution of tannic acid in distilled water (e.g. Mallinckrodt tannic acid N.F.

How do you make Congo red?

Congo Red is synthesised by coupling bis-diazotised benzidine with two molecules of napthionic acid. The blue dye so obtained is converted into its red disodium salt during its salting out with sodium chloride (Fig.

What is the purpose of using boiled yeast?

Boiling denatured the proteins in the yeast, preventing many essential cellular processes from being carried out.

How does boiling affect yeast cells?

Boiling will denature the proteins within the cell, and this will quickly stop all functions inside of the cell. The high temperature will also probably damage the cell wall of the yeast cell, and thus the cell also might rupture as a result.

How do you identify a yeast?

Physiological tests useful in yeast identification include (1) assimilation of carbohy-
drates, (2) assimilation of KN03, (3) fermentation of carbohydrates, (4) ability to grow.
at vitamin-free medium, (5) urease test, (6) pellicle formation on broth, and (7) ability.

How do you make a 1% Congo red solution?

2.2. Preparation of Congo Red 1000 mg/L (stock solution) was prepared by dissolving 1 g of congo red in 1 Liter of distilled water. 20, 40, 70 and 100 ppm solution prepared by dilution from the stock solution.

What is the use of Congo red?

Congo red was formerly used to dye cotton but has been superseded by dyes more resistant to light and to washing. It is still used in histology to stain tissues for microscopic examination, and to serve as an acid-base indicator, since it turns red in the presence of alkalies and blue when exposed to acids.

Can living yeast cells use active transport to keep a toxic material out of the cell?

In this case, the Congo red was toxic to the cells, so the living yeast (unboiled) used active transport to keep the dye particles outside the cell membrane. The plasma membranes of the living yeast were less permeable to Congo red, whereas the permeability of the plasma membranes increased when the cells died.

How do you demonstrate active transport?

To demonstrate active transport, ask students how to speed up the movement of the popcorn aroma. Discuss student responses. Place a fan near the bag of popcorn, and turn the fan on. Ask students how this would affect the movement of the air molecules.

Why are Congo red yeast cells turning blue?

The stained cells can then be viewed as they circulate throughout the cell. The red stained yeast cells (inside the formed food vacuole) will likely be seen turning blue in color as pH changes occur during digestion. Congo red is red at pH 5 and is various shades of blue at lower pHs.

What’s the best way to stain Congo red?

1. Place the coverslip with section in a ceramic staining rack . 2. Immerse sections in Harris Hematoxylin for 30 seconds to one (1) minute. 3. Wash with tap water until the water is clear. 4. Filter the Congo Red solution into a columbia staining dish (Thomas Scientific#8542-E40) 5.

What kind of solution does Congo red make?

Congo red has a propensity to aggregate in aqueous and organic solutions. The proposed mechanisms suggest hydrophobic interactions between the aromatic rings of the dye molecules, leading to a π–π stacking phenomenon.