Bacteria Flashcards
1
Q
Ancestors of bacteria
A
The ancestors of our current bacteria were unicellular micro-organisms that were the first forms of life to develop on earth about 4 billion years ago
2
Q
General characteristics of bacteria
A
- Most diverse and abundant group of organisms
- Inhabit practically all environments
- Mostly useful, some cause diseases
- Vary in shape:
- spherical bacteria called cocci
- rod-shaped called bacilli
- spiral shaped called spiralla
- comma shaped called vibrios - Can exist singly or in clumps
- In favourable conditions they reproduce rapidly by binary fusion
- In unfavourable conditions, may survive by becoming dormant. They form spores with a thick protective coat around themselves
5.
3
Q
Structure of bacteria
A
- Bacteria are unicellular
- Have a rigid cell wall
- Plasma membrane serves many purposes: 1. Serves as a mitochondrion, endoplasmic reticulum and sometimes even a chloroplast. 2. It also controls the entry and exit of materials
- Are prokaryotes: have no true nucleus, this is because they have no nuclear membrane
- Closed loop of dna
- Can have a waxy capsule as their outermost layer
- Some have flagella which enables them to move