Microbiology
Unit 1 – The microbial world
1.1 Microorganisms, tiny titans of the earth
Microbiology = the biology of microorganism
In microbiology distances range from molecules (10-9 m) to cells (10-5 m) (range of 4
orders of magnitude)
Microorganisms (microbes); microscopic organism consisting of a single cell or a cell
cluster or a virus.
Importance of microorganisms (microbes);
• Oldest form of live
• Largest mass of living material on Earth
• Carry out major processes for biogeochemical cycles
• Can live in places unsuitable for other organisms
• Other life forms require microbes to survive
Pathogens; microbes that cause disease.
Microbial culture; collection of cells that have been grown on a nutrient medium.
Medium; liquid or solid nutrient mixture.
1.2 Structure and activities of microbial cells
Elements of microbial structure
All cells have the following in common;
• Cytoplasmic (cell) membrane; barrier that separate the inside of the cells from
the outside environment
• Cytoplasm; aqueous mixture of macromolecules (proteins, lipids, nucleic acids
and polysaccharides), ions and ribosomes
• Ribosomes; protein-synthesizing structures
• Cell wall; present in most microbes; confers structural strength. Located
outside with cell membrane. Plant cells have this, animal cells not.
Prokaryotes (bacteria/archaea);
• No nucleus, but a nucleoid. Most have a single chromosome but some have
one or more small circles of DNA (plasmids)
• Generally smaller than eukaryotes
• No membrane enclosed organelles (no organelles)
Eukaryotes (planten/dieren);
• DNA enclosed in a membrane-bound nucleus
• Cells are larger and more complex
• Contain various organelles; mitochondria, nucleus.
, Activities of microbial cells
Properties of all cells;
Metabolism; cells take up nutrients
transport them and expel wastes
• Genetic; replication, transcription,
translation
• Catalytic; energy, biosynthesis
Growth; nutrients from the environment are
converted into new cells materials to form
new cells
Evolution; Cells evolve to display new properties
Properties of some cells;
Differentiation; some cells can from
new cells
Communication; cells interaction with
each other by chemical messengers
Genetic exchange; cells exchange
genes
Motility; some cells are capable of
self-propulsion (zelf-aandrijving)
1.3 Microorganisms and the biosphere
Microbes are the oldest form of life on Earth.
A brief history of life on earth
Earth 4,6 billion years
First microbial cells between 3,8 and 3,9 billion years
Atmosphere was anoxic (without O2) until 2 billion years
ago
Life was exclusively microbial until 1 billion year ago
LUCA (last universal common ancestor); from 2
domains; Bacteria and Archaea.
Later Archaea formed Archaea and Eukaryote
Eukaryote where the ancestors of multicellular
organisms.
Archaea are more closely related to eukaryotes.
Microbial abundance and activity in the biosphere
Extemophiles; microbes are even abundant
(overvloeding) in habitats that are too much harsh
for other forms of life; hot springs, glaciers and ice-
covered regions, high salt etc.
Microbial habitat; location in environment where microbial population lives.
Metabolic activities of microorganisms can change habitat in which they live, both
chemically and physically. These changes affect other organisms.
(meer voedingsstoffen tot een habitiat → sneller groeien microorganism → meer O2
gebruiken → habitiat word O2 vrij).
Unit 1 – The microbial world
1.1 Microorganisms, tiny titans of the earth
Microbiology = the biology of microorganism
In microbiology distances range from molecules (10-9 m) to cells (10-5 m) (range of 4
orders of magnitude)
Microorganisms (microbes); microscopic organism consisting of a single cell or a cell
cluster or a virus.
Importance of microorganisms (microbes);
• Oldest form of live
• Largest mass of living material on Earth
• Carry out major processes for biogeochemical cycles
• Can live in places unsuitable for other organisms
• Other life forms require microbes to survive
Pathogens; microbes that cause disease.
Microbial culture; collection of cells that have been grown on a nutrient medium.
Medium; liquid or solid nutrient mixture.
1.2 Structure and activities of microbial cells
Elements of microbial structure
All cells have the following in common;
• Cytoplasmic (cell) membrane; barrier that separate the inside of the cells from
the outside environment
• Cytoplasm; aqueous mixture of macromolecules (proteins, lipids, nucleic acids
and polysaccharides), ions and ribosomes
• Ribosomes; protein-synthesizing structures
• Cell wall; present in most microbes; confers structural strength. Located
outside with cell membrane. Plant cells have this, animal cells not.
Prokaryotes (bacteria/archaea);
• No nucleus, but a nucleoid. Most have a single chromosome but some have
one or more small circles of DNA (plasmids)
• Generally smaller than eukaryotes
• No membrane enclosed organelles (no organelles)
Eukaryotes (planten/dieren);
• DNA enclosed in a membrane-bound nucleus
• Cells are larger and more complex
• Contain various organelles; mitochondria, nucleus.
, Activities of microbial cells
Properties of all cells;
Metabolism; cells take up nutrients
transport them and expel wastes
• Genetic; replication, transcription,
translation
• Catalytic; energy, biosynthesis
Growth; nutrients from the environment are
converted into new cells materials to form
new cells
Evolution; Cells evolve to display new properties
Properties of some cells;
Differentiation; some cells can from
new cells
Communication; cells interaction with
each other by chemical messengers
Genetic exchange; cells exchange
genes
Motility; some cells are capable of
self-propulsion (zelf-aandrijving)
1.3 Microorganisms and the biosphere
Microbes are the oldest form of life on Earth.
A brief history of life on earth
Earth 4,6 billion years
First microbial cells between 3,8 and 3,9 billion years
Atmosphere was anoxic (without O2) until 2 billion years
ago
Life was exclusively microbial until 1 billion year ago
LUCA (last universal common ancestor); from 2
domains; Bacteria and Archaea.
Later Archaea formed Archaea and Eukaryote
Eukaryote where the ancestors of multicellular
organisms.
Archaea are more closely related to eukaryotes.
Microbial abundance and activity in the biosphere
Extemophiles; microbes are even abundant
(overvloeding) in habitats that are too much harsh
for other forms of life; hot springs, glaciers and ice-
covered regions, high salt etc.
Microbial habitat; location in environment where microbial population lives.
Metabolic activities of microorganisms can change habitat in which they live, both
chemically and physically. These changes affect other organisms.
(meer voedingsstoffen tot een habitiat → sneller groeien microorganism → meer O2
gebruiken → habitiat word O2 vrij).
