Cell Biology Revision Sheet

1. 📌 Essentials

• Cells are the basic units of life prokaryotic (bacteria) and eukaryotic (animal, plant).
• Eukaryotic cells contain a nucleus, mitochond, ribosomes; plant cells have additional cell wall and vacuole.
• Bacterial cells lack a nucleus, have circular DNA, and plasmids.
• Microscopes: light microscopes for general observation, electron microscopes for detailed internal structures.
• Diffusion moves particles from high to low concentration; osmosis is water diffusion across a membrane.
• Active transport moves substances against concentration gradient, requiring energy.
• Cell cycle involves growth, DNA replication, mitosis, producing identical daughter cells.
• Stem cells can differentiate into various cell types; embryonic stem cells are pluripotent.
• Exchange surfaces (alveoli, villi, gills) are adapted for efficient gas and nutrient exchange.
• Surface area to volume ratio influences cell efficiency; smaller cells have higher ratios.

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