Bacterial Morphology and Nomenclature

Question 1

What are the three main bacterial shapes?

Answer 1

Cocci (coccus) = round / spherical
Bacilli (bacillus) = rod shaped
Spirochaetes (spirilla) = spiral shaped

Question 2

What are other bacterial shapes (not round, rod, or spiral)?

Answer 2

Filamentous
Cured
Square
Pleomorphic

Question 3

What are types of bacterial arrangements?

Answer 3

Clumps
Chains
Twos / Diplo
Fours / Tetrads
Eights / Cubic

Question 4

What is a bacterial colony?

Answer 4

A visible mass of microorganisms all originating from a single mother cell

Question 5

What are common features of bacterial cell structure?

Answer 5

Cytoplasm = fluid inside the cell
Plasma / Cell membrane
Ribosomes
DNA = contained in a single chromosome located in the nuceloid
Plasmids = additional small rings of DNA

Question 6

What is gram staining?

Answer 6

Common technique used to differentiate the two classes of bacteria based on their different cell wall constituents

Question 7

What are the 5 steps in gram staining?

Answer 7

1. Fixation
2. Crystal violet
3. Iodine treatment
4. Decolourisation
5. Counterstain with safranin

Question 8

What are the possible results of gram staining and why does this happen?

Answer 8

Gram positive bacteria = purple
Gram negative bacteria = pink / red

Differences in cell wall thickness and peptidoglycan content

Some bacteria have no cell wall = no staining

Question 9

What is peptidoglycan?

Answer 9

Mesh-like structures that form cell walls outside the plasma membrane of most bacteria

Is a peptide, therefore consists of amino acids

Question 10

What is the linnaeus naming convention?

Answer 10

Latin name = Genus + Species + Strain

Example: Escherichia Coli K12