Life Sciences III: Microbiology lecture 1

Question 1

Bacterial cell morphology

Answer 1

Cocci: Sphere 1um

Bacilli: Roads, 0.5-1um (Width)
-3um (Length)

Spiral bacteria: 1¬3 and 0.3-0.6um in width

Question 2

Question 3

Arrangement of Cocci

Answer 3

May oval, elongated or flattened on one side

Cocci that remain in chains after devising are called strepcocci.

Cocci that remain in pairs after dividing are called Diplococci.

Cocci that divides into 2 planes which remain in groups of 4 are called tetrads.

Cocci that divide in three planes and remain in groups cube like groups of eight are called sarcinae.

Cocci that divide in multiple planes and form grape like clusters or sheets are called staphylococci.

Question 4

Arrangement of Bacilli

Answer 4

Most Bacilli appear as single rods

Diplobacilli appear after division.

Streptobacilli appear in chains after divison.

Some Bacilli are short and fat and are referred to as coccobracilli.

Question 5

Arrangement of spiral bacteria

Answer 5

Spiral bacteria have one or more twists

Vibrois have a curved rod shape.

Sprilla have a helical shape and fairly rigid bodies

Spirochetes have a helical shape and flexible bodies.
Spirochetes move by means of axial filaments.

Question 6

What are techniques to study the morphology of bacteria?

Answer 6

Light microscopy

Dark-field microscopy

Phase-contrast microscopy

Luminescent microscopy

Electron microscopy

Scanning Electron Microscopy

Question 7

Special Staining

Answer 7

Special Staining: more than one dye is used, special structures are seen.

Question 8

Differential staining (Fast acid staining)

Answer 8

Differential staining – more than one dye is used, differentiation between bacteria is possible