Cell Structure and Specialisation
Eukaryotic cells (like plant and animal cells) have their DNA safely stored in a nucleus, whilst prokaryotic cells (like bacteria) have their DNA floating freely in the cytoplasm. Think of eukaryotic cells as having a proper filing cabinet for their genetic information!
Plant cells are basically animal cells with extra kit - they've got chloroplasts for photosynthesis, a tough cell wall for support, and a permanent vacuole that acts like a water tank. Animal cells make do with just the basics: nucleus, cytoplasm, cell membrane, mitochondria, and ribosomes.
Specialised cells are like workers with specific jobs. Sperm cells have long tails for swimming, nerve cells have long connections for rapid signalling, and root hair cells have massive surface areas for absorbing water. Each cell's shape perfectly matches its function.
Key Tip: Remember that stem cells are like blank templates - they can become any type of cell your body needs, whether they come from bone marrow or plant meristems.
Microscopy and Measurement
When you're looking at cells under a microscope, magnification tells you how much bigger the image appears compared to real life. The formula is simple: magnification = image size ÷ real size. Electron microscopes give you much sharper images than light microscopes because they have higher resolution.
Mitosis is how cells make identical copies of themselves. The DNA replicates, chromosomes line up in the middle, then split apart to opposite ends before the whole cell divides. You end up with two genetically identical cells from one original.
Transport in Cells
Diffusion is particles naturally spreading out from crowded areas to less crowded ones - no energy required. Osmosis is specifically water moving through a partially permeable membrane from a dilute solution to a concentrated one.
Active transport is different - it needs energy from mitochondria because it's moving particles uphill, from low concentration to high concentration. Think of it like pushing water uphill instead of letting it flow downhill naturally.
