Microbiology 1010 – Lecture Notes
Part 1 – Microorganisms and Microbiology
What Is Microbiology?
The study of organisms too small to be seen with the naked
eye? o ex. Bacteria, viruses, single celled eukaryotes
Some microorganisms are visible to the naked eye:
ex. Fungi, algae
Some microbes are multicellular:
ex. Myxobacteria, slime molds
Better defining feature is cellular differentiation.
Prokaryotes – little/ no differentiation
Eukaryotes – highly differentiated
What Is Microbiology (Continued)
Microbiology is defined by techniques
Culture media for isolation and growth of organisms in pure culture
Biochemical to study cell components
Molecular and genetic techniques.
What is grown on a plate does not represent the overall population as sometimes some bacteria
does not grow on a plate.
1 Microbiology 1010 – Lecture Notes
Why Is Microbiology Important?
Microbes are the oldest form of life
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.
Million of years of go, there was no oxygen. Microbes started that for us.
Bacteria can fix nitrogen and change it to a usable form which is ammonia for the plants.
Plants create symbiotic relationships with rhizobacteria
1.2 Structure and Activities of Microbial Cells
All cells have the following in common:
Cytoplasmic membrane – Barrier that separates the inside of the cell from the outside
Cytoplasm – Aqueous mixture of macromolecules, ions, and proteins
Ribosomes – Site of protein synthesis
Plasma membrane is used to make ATP and a barrier to allow the proton concentration to
increase to couple for ATP production for the prokaryote
Fluid and everything else that is within the boundaries.
Cytoplasm = cells are made of 60 – 80% water . Cytoplasm is a polar solvent all intercellular
components are readily dissolved ( ex. enzymes etc.)
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Genetic material – All cells store their genetic information as DNA
o The information is divided into functional units called genes
Genome – A cell's full complement of genes
Chromosome – A genetic element carrying genes essential to cellular function
Plasmid – A piece of DNA that carries non-essential genes (ex. Genes for antibiotic resistance)
Genome - All of the genes found in a cell.
Prokaryotes – one circular chromosome. The region where the prokaryotes one chromosome resides
is the nucleoid.
Eukaryotes – many chromosomes.
Never have a living cell that stores it cells as RNA. RNA is an intermediate from DNA and
proteins. Virus – all the genetic material within the cell is RNA and they work with that.
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3 categories of microorganisms (based on structure)
Membrane bound nucleus
Membrane bound organelles
Complex internal organization
Division by mitosis and meiosis
More of a cost that comes with Eukaryotes.
Mitosis = asexual for the purpose of growth and repair.
Meiosis = it can be restored when fertilization takes place at a later time.
2 Major Groups of Eukaryotic Microbes
Protists – Unicellular or multi-cellular without differentiation into
tissues o Protozoa – animal-like microorganisms
o Algae – photosynthetic plant-like microorganisms
o Slime molds and water molds – filamentous
Fungi – Unicellular (yeasts), filamentous (molds), or multi-cellular (mushrooms).
Algae = is like plants (it’s similar to them) they are small
No membrane bound nucleus or organelles
Generally smaller (approx. 1 mm diameter)
Simple internal structure
Divide by binary fission
Most are unicellular
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When multicellular – it’s because they arrange themselves in communities/colonies.
Prokaryotes are unicellular.
When we talk about growing – we don’t mean about size. Cellular growth – cells dividing into tw, growing
Binary fission – takes a photo copy of their one circular chromosome. As that happens the cell simultaneously
elongates and pinches off in the middle. The result is two cells that are genetically identical. Some bacteria's can do
this in 20 minutes.
Nucleoid – the area in which there is a high statistical probability to find the prokaryotes genetic material.
They are small because they don’t have all the extra stuff that eukaryotes has.
2 Major Groups of Prokary