Simple Staining

Question 1

what are the Bacterial Shapes and Arrangements in cocci
- pairs
- chains
- clusters
- packets of 4
- packets of 8

Answer 1

Diplococcus → pairs

Streptococcus → chains

Staphylococcus → clusters (like grapes)

Tetrads → packets of 4

Sarcina → packets of 8

Question 2

what are the Bacterial Shapes and Arrangements in bacili
- pairs
- chains
- side by side fence-like arrangements

Answer 2

Diplobacillus → pairs

Streptobacillus → chains

Palisades → side-by-side “fence-like” arrangement

Question 3

what are the Bacterial Shapes and Arrangements in spiral bacteria
- curved rods
- helical rigid
- helical, flexible

Answer 3

Vibrios → curved rods (comma-shaped)

Spirilla → helical, rigid

Spirochetes → helical, flexible (crock-screw like)

Question 4

Why are basic stains preferred for simple staining?

Answer 4

uses only 1 dye (MB, crystal violet, carbol fuchsin)
Stains the bacteria → background remains clear.
Basic stains (cationic, positively charged) are used because bacterial cell walls & nucleic acids are negatively charged
Purpose: to see bacterial morphology (shape) and arrangement.

Question 4

procedure for simple staining

Answer 4

Flood fixed smear with methylene blue (1–2 minutes).

Gently wash with tap water (hold slide parallel to avoid washing off bacteria).

Blot dry with bibulous paper (don’t wipe).

Repeat for other organisms.

Examine under oil immersion.

Record → Draw and describe bacterial shape + arrangement.

Question 4

what to use to blot the slide dry

Answer 4

bibulous paper
- blot to remove excess water quickly
- do not wipe as it might scrape off

Question 5

purpose of simple staining

Answer 5

observe the morphology and arrangement