Prokaryote Cell Structure

Study Notes

Prokaryotes

Lack a true nucleus and membrane-bound organelles
Have a simple cellular structure, typically 1-10 microns in diameter
Are single-celled (unicellular) and can be filamentous (strings of single cells)
Have a capsule (slimy outer coating), cell wall, cell membrane, cytosol, and cytoplasm
Contain a single, large loop of DNA (nucleoid)
Have pili (for sticking to things), flagella (for swimming), and ribosomes (for building proteins)

Prokaryotic Lifestyle

Can be unicellular (alone) or form colonies (a film) or filaments (a chain of cells)
Can be photosynthetic (energy from sunlight), chemosynthetic (inorganic compounds as energy source), disease-causing (feed on living things), or decomposers (feed on dead things)

Eukaryotes

Have a true nucleus and membrane-enclosed organelles with specialized functions
Are larger and more complex in structure than prokaryotes
Can be multicellular and include animals, plants, fungi, and protists (algae and protozoans)
Have organelles, chromosomes, and a cytoskeleton that controls cell shape and movement
Have mini organs (organelles) with unique structures and functions located in the cytoplasm

Cell Components

Plasma Membrane

Acts as a gatekeeper, separating the cell from its external environment
Is selectively permeable and protects the cell, providing stability

Cytoplasm

Is a gel-like substance that dissolves substances like salt
Is involved in osmotic regulation and contains organelles

Nucleus

Is the control center of the cell, containing the DNA
Directs cell metabolism and cell reproduction

Other Organelles

Endoplasmic Reticulum: a transport system that carries materials throughout the cell
Ribosome: a protein factory that produces protein
Golgi Apparatus: a protein packaging system that temporarily stores protein for transportation
Lysosome: a suicidal bag of the cell that breaks down worn-out organelles or food
Mitochondria: the powerhouse of the cell, releasing energy from food molecules
Vacuoles: storage boxes that store materials like food, water, minerals, and waste products
Peroxisomes: vesicles that contain enzymes for detoxifying potentially harmful molecules
Intermediate Filaments: intertwined protein fibers that provide support and strength

Genetics

A gene can consist of a single DNA molecule (common in prokaryotes) or multiple DNA molecules (common in eukaryotes)
DNA molecules are packaged into chromosomes, which consist of chromatin (a complex of DNA and protein) in eukaryotes
Somatic cells have two sets of chromosomes, while gametes (reproductive cells) have half as many chromosomes
The centromere is the narrow waist of the duplicated chromosome, where the two chromatids are most closely attached

Description

Learn about the characteristics and components of prokaryote cells, including their size, shape, and organelles. Discover the functions of the capsule, cell wall, cell membrane, cytosol, and cytoplasm.