IGCSE Biology Revision Notes: Cell Structure and Function
IGCSE Biology Revision Notes: Cell Structure and Function
Cell structure and function is a fundamental topic in IGCSE Biology. These comprehensive revision notes cover cell types, organelles, transport mechanisms, and cell division, providing everything you need to master this essential topic for Cambridge and Edexcel IGCSE Biology.
Why Cell Structure and Function Matters
Understanding cells is crucial because:
- Foundation Topic - All biology builds on cell knowledge
- High Frequency - Appears in every exam paper
- Diagram-Heavy - Practice with diagrams improves marks
- Application - Links to many other topics
Cell Types
Prokaryotic Cells
- No nucleus
- DNA in cytoplasm
- No membrane-bound organelles
- Example: bacteria
Eukaryotic Cells
- Has nucleus
- DNA in nucleus
- Membrane-bound organelles
- Examples: plant and animal cells
Key Differences:
- Prokaryotes: smaller, simpler, no nucleus
- Eukaryotes: larger, more complex, has nucleus
Cell Organelles and Functions
Nucleus
- Contains DNA
- Controls cell activities
- Surrounded by nuclear membrane
- Contains nucleolus
Mitochondria
- Site of aerobic respiration
- Produces ATP (energy)
- Has own DNA
- Many in active cells
Ribosomes
- Site of protein synthesis
- Found on rough ER or free in cytoplasm
- Very small structures
- Made of RNA and protein
Endoplasmic Reticulum (ER)
- Rough ER: has ribosomes, protein synthesis
- Smooth ER: lipid synthesis, detoxification
- Network of membranes
- Connected to nucleus
Golgi Apparatus
- Modifies and packages proteins
- Forms vesicles for transport
- Stack of flattened membranes
- Prepares substances for secretion
Chloroplasts (Plant cells only)
- Site of photosynthesis
- Contains chlorophyll
- Has own DNA
- Converts light to chemical energy
Cell Membrane
- Controls what enters/leaves cell
- Made of phospholipids and proteins
- Fluid mosaic model
- Selectively permeable
Cell Wall (Plant cells only)
- Made of cellulose
- Provides support and structure
- Fully permeable
- Prevents cell bursting
Transport Across Membranes
Diffusion
- Movement from high to low concentration
- No energy required
- Passive process
- Example: oxygen into cells
Osmosis
- Movement of water
- Through selectively permeable membrane
- From high to low water potential
- Passive process
Active Transport
- Movement against concentration gradient
- Requires energy (ATP)
- Uses carrier proteins
- Example: mineral ions into root cells
Cell Division
Mitosis
- Produces identical cells
- For growth and repair
- Four stages: prophase, metaphase, anaphase, telophase
- Results in two daughter cells
Meiosis
- Produces gametes (sex cells)
- Reduces chromosome number by half
- Two divisions
- Results in four daughter cells
Exam Tips
1. Know Your Diagrams
- Practice drawing cells
- Label all structures
- Show relationships
- Use correct terminology
2. Understand Functions
- Don’t just memorize
- Understand why
- Link structure to function
- Apply to new situations
3. Compare and Contrast
- Prokaryotic vs eukaryotic
- Plant vs animal cells
- Different transport methods
- Mitosis vs meiosis
Related Resources
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Written by
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