Cellular Organelles: Quick Reference

Role: information storage and control center of the cell.
Structure: double-membrane nuclear envelope with nuclear pores; DNA inside the nucleus; mRNA exits to cytoplasm via pores.
Key facts: typically one nucleus per a typical eukaryotic cell; DNA remains in nucleus; RNA leaves as message for protein synthesis.

Role: powerhouse; ATP production via cellular respiration.
Structure: double membrane with inner membrane folds (cristae) increasing surface area.
Key facts: contains own DNA and ribosomes; can divide by binary fission; origin via endosymbiont event; many in energy-demanding cells.

Role: protein synthesis.
Structure: RNA + protein; not membrane-bound.
Location: free in cytoplasm or attached to rough endoplasmic reticulum (ER).
Note: present in both prokaryotes and eukaryotes; protein synthesis context depends on attachment site.

Rough ER: ribosomes present; synthesizes proteins destined for secretion or membrane insertion.
Smooth ER: lacks ribosomes; synthesizes lipids and detoxifies chemicals.
Connection: continuous with the nuclear envelope; serves as a manufacturing and sorting hub.

Role: sorts and packages proteins and lipids for transport; modifies cargo as needed.
Structure: stacked membranous sacs near the ER; often described as the cell’s post office.

Role: garbage disposal; digest macromolecules, old organelles, and pathogens.
Characteristics: acidic interior; contains digestive enzymes; membrane with protective sugars to prevent self-digestion.

Role: detoxification and oxidative reactions; detoxifies hydrogen peroxide.
Relationship: considered the cousin of the lysosome; sequesters reactive contents to protect the cytoplasm.

Role: photosynthesis; convert light energy to chemical energy (glucose).
Structure: double membrane; contains its own DNA and ribosomes.
Note: plants require chloroplasts and mitochondria; endosymbiont origin supported by shared features with mitochondria.

Definition: aqueous interior where organelles reside; supports diffusion and suspension of components.
Representation: often imagined as the gel-like matrix (e.g., Jell-O in demos).

Role: transport cargo between organelles and to/from the plasma membrane.
Nature: small membrane-bound sacs acting as shipping containers inside the cell.

Definition: network of membranes (ER, Golgi, lysosomes, vesicles) responsible for production, processing, and trafficking of cellular materials.
Key idea: coordinated flow of proteins and lipids through continuous/connected membranes.

Prokaryotes: no nucleus; no internal membranes; DNA in a nucleoid region; ribosomes; simpler organization; studio-apartment-like.
Eukaryotes: nucleus present; internal membrane-bound organelles; typically larger and more complex; can form multicellular organisms; same DNA across cells with functional differences due to protein expression.

Idea: mitochondria (and chloroplasts) originated as free-living prokaryotes engulfed by a host cell.
Evidence: own DNA and ribosomes; replicate by division similar to prokaryotes; double membranes.

Nuclear pores permit RNA export; DNA stays in nucleus.
Mitochondria and chloroplasts increase surface area to boost energy/biochemical output.
Rough ER vs Smooth ER delineate protein vs lipid/detox pathways.
Golgi = sorting/packaging; Lysosome = recycling/ digestion; Peroxisome = detoxification.
Cytoskeleton provides structural support and transport rails within the cell.
Endomembrane system = integrated network for processing and trafficking of cellular materials.