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Microbiology

The study of organisms that cannot be seen without magnification.

Microbes

Living things invisible to the unaided eye.

Microbiology

Organisms collectively referred to as microorganisms or microbes; the dominant form of life on Earth.

Medical Microbiology

Studies the microbes that cause disease.

Microbes

Single cell or multicellular organisms separated by prokaryotic and eukaryotic cells.

Prokaryotic Cell

Smaller in size, DNA in one long strand, no nucleus, no membrane-bound organelles.

Eukaryotic Cell

Larger in size, DNA in chromosomes, has a nucleus, has membrane-bound organelles.

Kinds of Microorganisms

Bacteria, Fungi, Protozoa, and Virus.

Bacteria

Unicellular, prokaryotes.

Fungi

Eukaryotic, can be multicellular or unicellular.

Protozoa

Unicellular, eukaryotes.

Virus

Not composed of cells, intracellular parasites with a capsid and nucleic acid.

Capsid

Protein coat of a virus.

Virus

Can survive outside the body depending on the virus, but can only replicate inside a host cell.

Measurement of Microorganisms

Uses metric units.

Metric System

Units differ by factors of 10 to make conversions easier.

Scientific Notation

Useful way to express very large or very small numbers

Light Microscope

~1 mm to ~ 1 µm

Electron Microscope

Less than 1 µm

Robert Hooke

Saw first microbes and introduced the name “cell”.

Anton van Leeuwenhoek

First to see and describe bacteria, considered the first Microbiologist.

Abiogenesis/Spontaneous Generation

Living organisms can be generated from non-living things.

Theory of Biogenesis

Living things come from other living things.

Germ Theory of Disease

Microorganisms cause disease.

Recent Discoveries in Microbiology

Allowed us to view viruses and cellular components in more detail; vaccinations, genomic sequencing, and bioengineering.

Animalia (Kingdom of Animals)

Kingdom that includes organisms that move and get energy from breaking down food through cellular respiration.

Plantae (Kingdom of Plants)

Kingdom that includes organisms that don’t move and use light energy to generate their own food through photosynthesis.

Taxonomy

Science of classification, organizing living organisms into groups based on similarities and differences

Phylogenetics

Tracking evolutionary descent of an animal through studying the genetic material

Robert Hook

Introduced the name “cell” in the 1600s.

Matthias Schleiden

Stated that all plants are made of cells in the 1830s.

Theodor Schwann

Stated that all animals are made of cells in the 1830s

Rudolf Virchow’s Cell Theory

Cell is the basic unit of all organisms. All living things are made of cells. All cells come from pre-existing cells.

Kingdom Protista

Single celled organisms that didn’t fit easily into plant or animal kingdoms were then grouped into this kingdom in 1866.

Kingdom Fungi

Macroscopic or microscopic. Decomposers: break down dead plants and animals to recycle nutrients. Different from photosynthesis (plants) and ingestion (animals)

Prokaryotic

“before nucleus”

Eukaryotic

“true nucleus”

Archaea

Organize their DNA or RNA (ribosomes) in different ways. Are more similar to eukaryotic cells. Plasma membrane has different lipids (ether-linked) from bacteria and eukaryotes (ester linked)

Domain Bacteria

Prokaryotes with peptidoglycans in their cell walls

Domain Archaea

Prokaryotes who often live in extreme environments without peptidoglycans in their cell walls

Domain Eukarya

DNA is in a compartment called nucleus

Domain Archaea

First identified in extreme environments but now know that they live in diverse habitats: soil, water, in organisms, and extreme environments. Considered to be more related to humans than they are to bacteria! None have currently been found to cause disease

Carl Linnaeus

Father of Taxonomy who introduced a system for organizing, classifying and naming organisms

Binomial Nomenclature

Genus species

Identifying Bacteria

Selective media do not allow some types of bacteria to grow, while allowing rapid growth of another type. Differential media allow one to see visible changes in the media that are associated with a specific type of bacteria.

Staphylococcus aureus

Round bacteria that grow in clusters and form golden colonies on agar plates: “golden grape clusters”

Strain

A subgroup of a species with one or more characteristics that distinguish it from other subgroups of the same species.

Bacterial Growth

Increase in cell NUMBER through cell division

Obligate aerobes

MUST have oxygen to survive

Facultative anaerobes

Can use oxygen if it is there but can also live without

Obligate anaerobes

Prefer to grow without oxygen and May be harmed by oxygen

Aerotolerant anaerobes

Do not use oxygen but can tolerate it

Cultural medium

Has the perfect nutrients, salt level and pH for the microbe you want to grow

Binary Fission

Each bacterial cell makes an exact copy of itself. The time required to perform a division is the generation time. Average generation time is 1-3 hours

Lag Phase

No division, cells are settling into their new environment, lots of metabolic activity as cells get ready to divide

Log Phase

Once cells have enough energy and materials they start rapidly dividing. Growth is logarithmic.

Stationary Phase

Usually the microbes start to exhaust nutrient supply and stop dividing

Death Phase

More cells die than are being made and cells are killed by built up waste products

Diluent

A solution used to dilute the samples (e.g. water, saline, buffer)

Dilution Factor (DF)

The amount of original solution / Total amount of new solution you made

Elements

Substances that cannot be broken down into simpler substances by chemical reactions.

Atom

The basic building block of all matter and is the smallest unit of matter that has the properties of a chemical element.

Proton

Subatomic particle with a positive charge located in the nucleus.

Neutron

Subatomic particle with a neutral charge located in the nucleus.

Electron

Subatomic particle with a negative charge that orbits the nucleus in shells.

Atomic Mass

The mass of an atom of an element, calculated by adding the number of protons and neutrons.

Atomic Number

The number of protons in an atom of an element.

Isotopes

Atoms of an element with the same number of protons but different numbers of neutrons, resulting in different atomic masses.

Radioactive Isotopes

Unstable isotopes that emit radiation as they decay to become more stable.

Autoradiography

A technique that detects the decay of radioisotopes, used in various scientific and clinical applications.

Energy Shells

Electrons are contained within these

Valence Shell

The outermost shell of an atom that contains electrons.

Inert Atom

Atoms that have full outer shell and does not react with other atoms.

Ions

Atoms with an electrical charge (positive or negative) due to the loss or gain of electrons.

Cations

Positively-charged ions.

Anions

Negatively-charged ions.

Chemical Reaction

The process of building and/or breaking chemical bonds between atoms or molecules.

Reactants

Atoms or molecules that interact in a chemical reaction.

Product

The result of a chemical reaction.

Ionic Bonds

Chemical bonds that form when one or more electrons are transferred between atoms.

Covalent Bonds

Chemical bonds that form when electrons are shared between atoms.

Non-polar Covalent Bonds

Covalent bonds with the electrons shared equally between atoms

Polar Covalent Bonds

Covalent bonds with the electrons shared unequally between atoms due to electronegativity differences.

Electronegativity

The attraction of a nucleus for electrons, influencing the type of bonds an atom is likely to form.

Oxidation

The loss of electrons or hydrogen atoms from a molecule.

Reduction

The gain of electrons or hydrogen atoms by a molecule.

Importance of Water

Water is essential for life on Earth, as all living organisms are predominantly made of water.

Molecular Structure of Water

H2O, formed by covalent bonds between an oxygen atom and two hydrogen atoms.

Electronegativity and Polarity

Electrons are not shared equally; oxygen is highly electronegative and attracts electrons, making water polar.

Polar Covalent Bonds

Due to unequal sharing of electrons, water molecules have a partial positive end (hydrogen side) and a partial negative end (oxygen side).

Hydrogen Bonding

Interaction between the partial positive charge of one molecule and the partial negative charge of another, causing molecules to clump together.

Hydrogen Bonds

Can form between any polar molecules and are weaker than covalent and ionic bonds individually, but strong in numbers.

Hydrogen Bonds in DNA

Base pairs of DNA strands are held together by hydrogen bonds, which can be easily broken for DNA replication.

Ionic Molecules and Water

Ionic bonds dissociate in water because they attract water molecules, causing polar water molecules to become ordered around the ions.

Electrolyte

Water with ions present that can conduct an electrical charge.

Dissociation of Water

Water molecules sometimes fall apart into hydrogen ions (H+) and hydroxide ions (OH-).

pH Definition

The negative log of hydrogen ion concentration; a pH of 4 has an [H+] of 10^-4.

Acids

pH < 7.0; release or donate H+ ions, which lowers the pH when added to water.

Acids and pH

Acids lower the pH by adding H+ ions to the solution.

Bases

pH > 7.0; release OH- or combine with H+ ions, which increases the pH when added to water.