Cell Biology Calculators

0 calculators tagged with “Cell Biology”

Cell biology (cytology) is the scientific study of the structure, function, and behavior of cells — the fundamental units of life. It encompasses the organization of cellular components (organelles, membranes, cytoskeleton), cell cycle regulation (mitosis, meiosis), cell signaling, membrane transport, cell-cell interactions, and the molecular mechanisms driving cell division, differentiation, and death. Cell biology bridges biochemistry and genetics, providing the mechanistic framework for understanding development, disease, and the response of organisms to their environment.

All Calculators

No calculators found for this topic.

Prokaryotic vs. Eukaryotic Cells

  • Prokaryotes: No membrane-bound nucleus; circular DNA chromosome; no membrane-bound organelles; ribosomes 70S; cell wall (peptidoglycan in bacteria); small (~1–10 μm)
  • Eukaryotes: Membrane-bound nucleus; linear chromosomes; membrane-bound organelles; ribosomes 80S (cytoplasmic); ~10–100 μm; includes animals, plants, fungi, protists

Major Organelles and Functions

  • Nucleus: Contains DNA; site of transcription; separated from cytoplasm by nuclear envelope with pores
  • Mitochondria: ATP production via oxidative phosphorylation; own circular DNA; double membrane; matrix and intermembrane space
  • Endoplasmic reticulum: Rough ER — protein synthesis (ribosomes); smooth ER — lipid synthesis, calcium storage, detoxification
  • Golgi apparatus: Protein modification, sorting, and secretion; cis (receiving) to trans (shipping) face
  • Lysosomes: Acidic (pH ~5); contain hydrolytic enzymes; digest engulfed materials; cellular recycling (autophagy)
  • Chloroplasts (plants): Photosynthesis; own DNA; thylakoids (light reactions) and stroma (Calvin cycle)

Cell Cycle

G1 → S (DNA replication) → G2 → M (mitosis). Checkpoints: G1/S (restriction point, CDK4/6-cyclin D); G2/M (CDK1-cyclin B); Spindle assembly checkpoint. p53 is the guardian of the genome — activates DNA damage checkpoints. Cancer: uncontrolled cell cycle progression (CDK overactivation, p53/RB loss).

Glossary

Cell Biology (Cytology)
The scientific study of cell structure, function, and processes; encompasses organelle biology, cell cycle, signaling, membrane transport, and cell-cell interactions.
Endosymbiotic Theory
The hypothesis that mitochondria and chloroplasts evolved from free-living prokaryotes engulfed by ancestral eukaryotes; supported by their circular DNA, 70S ribosomes, and double membranes.
Cell Cycle Checkpoint
A regulatory control point that arrests the cell cycle if DNA is damaged or conditions are unsuitable; G1/S checkpoint (RB/p53); G2/M checkpoint (CDK1-cyclin B); spindle assembly checkpoint.

Frequently Asked Questions

Prokaryotic cells (bacteria, archaea): no membrane-bound nucleus (DNA in nucleoid region); no membrane-bound organelles; 70S ribosomes; cell walls (peptidoglycan in bacteria); binary fission; typically 1–10 μm; circular chromosome(s). Eukaryotic cells (animals, plants, fungi, protists): nucleus enclosed by double membrane; multiple membrane-bound organelles (mitochondria, ER, Golgi, lysosomes); 80S ribosomes; mitosis/meiosis for division; 10–100 μm. Endosymbiotic theory explains mitochondria and chloroplasts as former prokaryotes engulfed by ancestral eukaryotes (evidence: own circular DNA, 70S ribosomes, double membrane, binary fission).

Nucleus: stores DNA; site of transcription and mRNA processing; separated by nuclear envelope with nuclear pore complexes. Mitochondria: produce ~30–32 ATP/glucose by oxidative phosphorylation; site of TCA cycle; contain own circular DNA. ER (rough): protein synthesis and folding (membrane-bound ribosomes); entry point for secretory pathway. ER (smooth): lipid synthesis; Ca²⁺ storage; drug detoxification (CYP450 enzymes). Golgi: protein modification (glycosylation), sorting, packaging into vesicles for secretion or lysosomal targeting. Lysosomes: pH ~5; hydrolytic enzymes digest organelles (autophagy), bacteria (phagocytosis), and macromolecules.

Cell cycle: G1 (growth, preparation) → S phase (DNA replication, ~8 hours) → G2 (preparation for division) → M phase (mitosis, ~1 hour). Regulated by cyclin-dependent kinases (CDKs) and their cyclin partners: Cyclin D/CDK4,6 → G1 progression; Cyclin E/CDK2 → G1/S transition; Cyclin A/CDK2 → S phase; Cyclin B/CDK1 → G2/M transition. Tumor suppressor RB blocks E2F transcription factor (inhibiting S-phase genes) until phosphorylated by CDK4/6. p53 activates p21 (CDK inhibitor) in response to DNA damage, halting the cycle for repair. Cancer cells commonly have CDK overactivation or RB/p53 loss.

Key cell biology techniques: Light microscopy — phase contrast (live unstained cells), fluorescence (labeled proteins, organelles), confocal (3D optical sections). Electron microscopy (TEM, SEM) — nm resolution for ultrastructure. Flow cytometry — cell sorting and analysis of surface/intracellular markers, cell cycle analysis. Western blotting — protein detection and size. Immunofluorescence — protein localization in fixed cells. Live-cell imaging — GFP-tagged proteins followed in real time. CRISPR — gene editing to determine function. RNAi/siRNA — transient gene knockdown. Mass spectrometry — proteomics, protein identification.