Key Concepts in Microbiology and Cell Chemistry

Three Domains of Life

Bacteria, Archaea, and Eukarya.

Cell Features

Cell membrane, cytoplasm, ribosomes, and genetic material (DNA/RNA).

Prokaryotes vs. Eukaryotes

Prokaryotes lack a nucleus and membrane-bound organelles; eukaryotes have both.

Viruses vs. Cells

Viruses lack cellular structures and cannot reproduce independently.

Microorganism Sizes

Viruses < Prokaryotes < Microeukaryotes.

Microbial History

Microbes have existed for over 3.5 billion years, contributing to various aspects of Earth.

Applications of Microbiology

Used in medicine, biotechnology, and food production.

Binomial Nomenclature

Genus capitalized, species lowercase (e.g., Escherichia coli).

Taxonomic Levels

Domain > Phylum > Class > Order > Family > Genus > Species.

Essential Elements in Biology

Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, and Sulfur (CHNOPS).

Atom Structure

Nucleus with protons, neutrons, surrounded by electrons.

Chemical Bonds

Covalent (strong), Ionic (weaker), Hydrogen (weakest).

Ion Formation

Losing/gaining an electron forms an ion; losing/gaining a proton changes the element.

Polar vs. Nonpolar Covalent Bonds

Polar: unequal sharing (e.g., water); Nonpolar: equal sharing (e.g., oxygen gas).

Water Molecule Polarity

Hydrogen atoms have a partial positive charge; oxygen atom has a partial negative charge.

[H+] and pH Relationship

High [H+] = low pH (acidic), Low [H+] = high pH (basic), pH 7 = neutral.

Macromolecules

Carbohydrates, Lipids, Proteins, Nucleic acids.

Bacterial Cell Morphologies

Coccus (Spherical), Bacillus (Rod-shaped), Spirillum (Spiral-shaped).

Gram Positive vs. Gram Negative Cells

Gram-positive: Thick peptidoglycan, stains purple. Gram-negative: Thin peptidoglycan, outer membrane, stains pink.

Eukaryotic Cell Structure

Nucleus and organelles present.

Organelle Definition

Specialized structure within a cell (e.g., nucleus, mitochondria).

Eukaryotic vs. Prokaryotic Ribosomes

Eukaryotic ribosomes are larger (80S) than prokaryotic ribosomes (70S).

Yeast vs. Mold Structures

Yeasts are unicellular; molds are multicellular with filamentous structures.

Protozoa Classification

Amoebas (pseudopodia), Ciliates (cilia), Flagellates (flagella), Apicomplexans (non-motile).

Virus Features

Lack cellular structures and independent reproduction.

Virus Structure

Consists of a capsid and genetic material (DNA or RNA).

Viral Shapes

Helical (e.g., tobacco mosaic virus), Icosahedral (e.g., adenovirus), Complex (e.g., bacteriophage).

Virus Replication (Lytic Cycle)

Virus enters cell, replicates, and lyses the host cell.

Lysogenic vs. Lytic Cycle

Lysogenic: Viral DNA integrates into host genome and remains dormant.

Enveloped vs. Non-enveloped Viruses

Enveloped viruses have a lipid membrane; non-enveloped viruses do not.