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Kingdom Monera
Characteristics of Bacteria
1. Size—smallest cells (around 1 micrometer)
2. Shape—three basic shapes:
a) round, known as coccus
b) rod, known as bacillus
c) spiral, known as spirillus
Note: Prefixes are used to indicate a colonial arrangement of certain types
of bacteria
Ex) Diplo = pair (two), Staphylo = clusters, Strepto = chain, Tetrad =
four, Sarcina = cube (eight)
Examples:
Streptococcus lactis—in milk, sours
Diplococcus pneumonia—causes pneumonia
Staphylococcus pepogenes—causes boils
Structure of a typical bacterium
Contains: a cell membrane, ribosomes, cell wall (keeps osmotic
pressure), chromatin, cytoplasm, capsule (protects the cell from our
immune system/viruses), and flagellas. No other structures (ER,
vacuoles, etc.) are present. The only organelle is the ribosome. Cellular
respiration takes place along the inside surface of the cell membrane.
Bacterial nutrition
Two types: 1. Autotrophic
2. Heterotrophic
a) photosynthetic (light) or
b) chemosynthetic
a) saprophytes (feed on dead organisms) or
b) parasite (feed on living organisms)
Reproduction in bacteria
1. Asexual—Binary fission
-The chromatin is duplicated, it moves to opposite ends as the mother
cell divides in half. Each new daughter cell has the same genetic
material.
2. Sexual—by conjunction (only when conditions are unfavourable)
Two other ways that new strains are created are:
a) Transduction—transmission of genetic material from one
bacterium to another by a virus
b) Transformations—DNA released from a dead bacterium is
picked up by a live bacterium, resulting in a new strain
Some bacteria will form an endospore during unfavourable conditions (ie.
boiling, freezing, or drought), before developing into an active cell again
when the conditions change.