Cell Biology of Prokaryotes and Eukaryotes

Lecture on 1/21/2026

Shared Features of All Microbial Cells (Pro and Eu)

membrane composed of phospholipid bilayer, DNA based genome, ribosomes*, and various proteins* (*don’t always look the same)

Peptidoglycan

polymer made up of two monomer sugar molecules called N-acetylglucosamine (NAG) and N-Acetylmuramic Acid (NAM); Found in bacteria ONLY

Teichoic Acids

chains of phosphodiester-linked sugar alcohols like glycerol or ribityl

S-layer

an important virulence factor for some cells; aids in adherence to host tissues

Nucleoid

DNA in a bacteria cell that is organized in a region centrally located in the cell

Origin of Replication (ori)

the circular chromosome of the cell connects back at a central point

Prokaryotic Ribosomes Subunits

30S and 50S (all together: 70S)

Eukaryotic Ribosomes Subunits

40S and 60S (all together: 80S)

Binary Fission

process bacterial cells go through to make more of themselves by replicating its DNA

Endospore

a form bacterial cells go into when environmental conditions get too harsh that allow for dormancy and protection from the harsh conditions

Chemotaxis

sensor proteins that detect and sense chemicals in the environment, which either repel them away, or encourage them towards a certain chemical

Eukaryotic Cell Components

Smooth and Rough ER, Nucleolus, Nucleus, Golgi, Mitochondrion, Plasma Membrane, Peroxisomes, Lysosomes

Smooth ER

no ribosomes; makes lipids, phospholipids, sterols, etc.

Rough ER

has ribosomes; protein synthesis

Lysosome

membrane enclosed organelle that contains enzymes capable of biological material degradation

Peroxisomes

contain enzymes involved in a variety of metabolic reactions

Golgi apparatus

directs and organizes where molecules in the cell should go

Pili

Fimbriae (attach to surface) and Conjugation (transfer DNA) pilus

Stalks

membranous extensions of cytoplasm that secrete adhesion factors (called holdfasts)

Advantages of Membranous Organelles

increased surface area without increased cell volume, enable different reactions simultaneously, compartmentalization protects cytoplasmic components from harmful substances

Nucleus

an intracellular double membrane-enclosed compartment containing chromatin; stores genome; stores nucleolus

Nucleolus

where ribosomes are assembled within a nucleus

Free Ribosomes

found in cytoplasm to synthesis water-soluble proteins

Membrane-bound Ribosomes

attached to Rough Endoplasmic Reticulum to make other types of proteins for the cell

Mitosis

produces two genetically identical daughter cells, each with the same number of chromosomes as the original cell; for growth, repair and asexual reproduction (diploid to diploid)

Meiosis

produces gametes (sperm/eggs in animals, pollen/ovules in plants) by reducing chromosome number by half (diploid to haploid); for sexual reproduction

Microfilaments

actin filaments; smallest and thinnest; key for movement and structure

Intermediate Filaments

medium sized; provide structural stability and anchor organelles by forming a meshwork under cell membrane

Microtubules

largest and hollow; transport substances within the cell; form spindle fibers, cilia, and flagella