Cell Biology Fundamentals

The cell world is divided into two main types: prokaryotes $no nucleus - think bacteria$ and eukaryotes $with a nucleus - that's us and plants$. Think of the nucleus as the cell's control centre, like the headteacher's office in your school.

Animal cells and plant cells share many parts but have key differences. Both have cytoplasm $the jelly-like stuff inside$, a nucleus, ribosomes, mitochondria, and a cell membrane. However, plant cells get three exclusive extras: a cell wall for structure, chloroplasts for photosynthesis, and a large vacuole for storage.

Each part has a specific job. The mitochondria are your cell's power stations, releasing energy through respiration. Ribosomes are tiny protein factories, whilst the cell membrane acts like a selective bouncer, controlling what gets in and out.

Quick Tip: Remember that chloroplasts contain chlorophyll - that's what makes plants green and lets them make their own food!

Stem cells are special because they're unspecialised and can become any type of cell. Embryonic stem cells could potentially treat diseases like diabetes, whilst adult stem cells and plant meristem cells help with repair and growth.

The cell cycle is how cells multiply: they grow bigger, make new organelles, copy their chromosomes through mitosis, then split into two identical cells. This process, called differentiation, allows cells to become specialised for specific jobs.

Diffusion happens when particles move from areas of high concentration to low concentration - like perfume spreading across a room. The bigger the concentration gradient (difference in concentration), the faster this happens. Surface area also matters: more surface area means faster diffusion rates.