Darwin’s evolutionary theory - Evolution as such is the simple proposition that the characteristics of organisms change over time. 

Geometric increase 

Limited food & Space

Struggle for existence 

Variation 

Natural selection

Inheritance of useful characters

Speciation 

TLS Online TPP Program

#Id: 537

#Unit 2. Cellular Organization

The shape of a bacterium is governed by its rigid cell wall.

TLS Online TPP Program

#Id: 538

#Unit 2. Cellular Organization

Some bacterial species are pleomorphic. Example: genera Arthrobacter, Corynebacterium, Mycobacterium, Mycoplasma, etc.

TLS Online TPP Program

#Id: 539

#Unit 2. Cellular Organization

Helical bacteria with: 

1. Less than one turn- vibrioid shape

2. Complete turn- helical shape

TLS Online TPP Program

#Id: 540

#Unit 2. Cellular Organization

Protein filaments in cytoplasm are responsible for the rod and helical cell shapes of bacteria.

TLS Online TPP Program

#Id: 541

#Unit 2. Cellular Organization

Flagella may be:

1. Peritrichous

2. Monotrichous 

3. Lophotrichous

4. Amphitrichous 

TLS Online TPP Program

#Id: 542

#Unit 2. Cellular Organization

Hook and filament are composed of monomeric subunits (flagellin) arranged in a helical fashion.