🧫 Cell Structure
Animal Cells
The basic unit of life in animals. Key structures:
- Nucleus – Contains DNA, controls cell
- Cytoplasm – Site of chemical reactions
- Cell membrane – Controls what enters and leaves
- Mitochondria – Where respiration happens (energy)
- Ribosomes – Make proteins
Plant Cells
Similar to animal cells but with extras for photosynthesis:
- Cell wall – Supports the cell, made of cellulose
- Chloroplasts – Contain chlorophyll for photosynthesis
- Permanent vacuole – Stores sap, helps structure
Bacterial Cells
Prokaryotic (no nucleus). Key features:
- DNA loop – Floats freely in cytoplasm
- Plasmids – Small loops of DNA (used in genetic engineering)
- Cell wall – Supports cell (not made of cellulose)
- No mitochondria or chloroplasts
🔍 Microscopy
To study cells, we use microscopes. Two main types:
Light Microscopes
- Use light to magnify images
- Can view live cells
- Limited magnification and resolution
Electron Microscopes
- Use electrons, much higher magnification
- Can see internal cell structures (e.g. ribosomes)
- Cells must be dead, very expensive
Key Terms:
- Magnification = How much bigger the image is than the real object
- Resolution = The ability to see two points as separate
🔁 Cell Division and the Cell Cycle
The Cell Cycle
- Growth – Cell grows, increases organelles
- DNA Replication – Chromosomes double
- Mitosis – Cell divides into two identical daughter cells
- Cytokinesis – Cell fully splits
Mitosis
- Happens in growth and repair
- Produces 2 genetically identical diploid cells
- Happens in skin, bone, hair etc.
🌱 Stem Cells
Stem cells can become different types of cells. Two types:
Embryonic Stem Cells
- Found in early embryos
- Can become any cell type
- Used to treat diabetes, paralysis
Adult Stem Cells
- Found in bone marrow
- Can become limited types (e.g. blood cells)
- Fewer ethical concerns
Plant Stem Cells
- Found in meristems
- Can clone plants quickly
- Preserve rare species, mass-produce crops
Ethical + Practical Issues
- Embryo use raises moral questions
- Risk of cancer or infection from transplants
- Research tightly controlled
🚚 Transport in Cells
Cells need to move substances in and out.
Diffusion
- Movement from high → low concentration
- Happens in gases or liquids
- E.g. Oxygen into lungs, CO₂ out
Osmosis
- Movement of water across a membrane
- From dilute → concentrated solution
- Important in root hair cells and cells not bursting
Active Transport
- Moves substances against the gradient
- Needs energy (ATP)
- E.g. Root hair cells absorb mineral ions from soil
- E.g. Glucose reabsorbed in kidney
Usefull Resources
Some other usefull revision resources
🧠 Revision Notes & Study Guides
- BBC Bitesize – Cell Biology
Interactive explanations, diagrams, and quizzes tailored to the AQA spec.
👉 BBC Bitesize Cell Biology - Physics & Maths Tutor – Topic 1: Cell Biology
Clear summary notes, exam-style questions, and flashcards.
👉 PMT Cell Biology - Save My Exams – AQA Biology B1
Concise revision notes with diagrams and exam tips.
👉 Save My Exams Cell Biology - Knowunity – B1 Cell Biology Notes
Student-made summaries with examples of specialised cells.
👉 Knowunity B1 Notes - Biofidelity – Cells Revision Cards
Teacher made revision cards and labled by section of unit
👉 Biofidelity Cells Revevion Cards
📚 Printable & Visual Aids
- Physics & Maths Tutor – Detailed Notes (PDF)
In-depth printable notes with diagrams and explanations.
👉 Download PDF - Nottingham Free School – Knowledge Organiser
One-page summary of key definitions and processes.
👉 Download Organiser
🎮 Interactive & Gamified Tools
- Quizlet – B1 Cell Biology Flashcards
Pre-made flashcards covering key terms and concepts.
👉 Quizlet Flashcards - Twinkl – AQA Cell Biology Resources
Worksheets, quizzes, and games designed for GCSE students.
👉 Twinkl Resources
🎥 Video Tutorials
- Dr Shaun Donnelly – Free Science Lessons
Short, focused videos explaining key topics in cell biology.
👉 Free Science Lessons Cell Biology
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