Explore the building blocks of life through animated simulations, interactive diagrams, and a comprehensive quiz. Based on the university lecture by RNDr. Petr Fleissig.
Begin Exploring ↓Bacteria, Archaea, and Eukaryota – the fundamental classification of all cellular organisms
Compare prokaryotic and eukaryotic cells – hover to discover each organelle
Phospholipid bilayer with proteins and sterols – the semi-permeable barrier
Watch how cells respond to isotonic, hypertonic, and hypotonic solutions
Structural protection varies across organisms – from cellulose to chitin to peptidoglycan
Made of cellulose (fibers connected by hemicellulose + pectin). Features a middle lamella between adjacent cells and plasmodesmata (channels) for cell-to-cell communication. Can be reinforced with lignin (wood), cutin (waxy coating on leaves), or silica.
Built from chitin (a polysaccharide). The same material forms the exoskeletons of arthropods — evidence of the evolutionary relationship between fungi and animals. Both chitin and cellulose are practically indigestible (dietary fiber).
Gram-positive (G+): thick peptidoglycan (murein) layer. Gram-negative (G-): thin peptidoglycan + outer membrane with porin proteins. Human cells lack peptidoglycan, which is why our immune system can target it.
Animal cells lack a cell wall entirely. Instead, their surface is covered by the glycocalyx — a "sugar coat" of carbohydrate chains on the membrane. This determines blood types (A, B, AB, O) and enables cell recognition. The absence of a wall allows phagocytosis.
Single-membrane and semi-autonomous organelles – the cell's internal machinery
Named after Italian physician C. Golgi (Nobel Prize). System of flat cisternae that receives protein-filled vesicles from the ER and performs post-translational modifications — folding, glycosylation, and sorting for delivery.
Vesicles packed with digestive enzymes. Break down materials brought in by endocytosis, damaged organelles, and cellular waste. The cell's recycling center.
Rough ER: ribosomes on surface → protein factory. Smooth ER: no ribosomes → produces cholesterol, phospholipids, stores Ca²⁺. Connected to the nuclear envelope. Name means "network within the cytoplasm."
In plant cells: large central vacuole (up to 90% of volume) bounded by the tonoplast membrane. Contains water, protective alkaloids, tannins, pigments (anthocyanins), and enzymes (e.g., bromelain in pineapple). In protists: contractile vacuoles pump out excess water.
The energy powerhouse. Double membrane — inner membrane folded into cristae; interior is the matrix. Produces ATP (adenosine triphosphate) via cellular respiration. Hundreds per cell. Has its own circular DNA — evidence of bacterial ancestry.
Endosymbiotic origin from cyanobacteria (~1 billion years ago). Double membrane + thylakoid discs containing chlorophyll. Stacked thylakoids = grana; fluid = stroma. Perform photosynthesis: convert light energy to glucose.
Chromoplasts: contain carotenoids (red carotenes, yellow xanthophylls) — color ripe fruits and flowers. Leukoplasts: colorless; store starch (amyloplasts in potatoes, cereals). All plastids arise from proplastids and can interconvert.
| Feature | Photosynthesis | Cellular Respiration |
|---|---|---|
| Location | Chloroplast | Mitochondria |
| Energy | Absorbed (light) | Released (ATP) |
| Inputs | CO₂, H₂O, light | C₆H₁₂O₆, O₂ |
| Outputs | C₆H₁₂O₆, O₂ | CO₂, H₂O, ATP |
| Equation | 6CO₂ + 6H₂O + light → C₆H₁₂O₆ + 6O₂ | C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP |
Watch molecules flow through photosynthesis, respiration, and fermentation
The cell's internal skeleton – microtubules, microfilaments, and intermediate filaments
Test your understanding – 25 questions covering all topics