Microscopy

This page focuses on microscopy techniques, a crucial topic in GCSE Cell Biology. It compares light microscopes and electron microscopes, detailing their capabilities and limitations.

Light microscopes:

• Magnify up to 2,000x with a resolution of 200nm
• Use a beam of light
• Can produce color images
• Allow observation of living samples
• Are relatively small, inexpensive, and simple to use

Electron microscopes:

• Magnify up to 2,000,000x with a resolution of 0.2-10nm
• Use a beam of electrons
• Produce black and white images
• Require dead samples
• Are large, expensive, and require specialized training

The page also outlines a required practical for preparing and observing cells under a microscope, including potential errors to avoid.

Example: The first cells were observed by Robert Hooke in 1665 using a light microscope.

Definition: Magnification of a light microscope = magnification of eyepiece lens × objective lens

Highlight: Electron microscopes, developed in the 1930s, allow viewing of subcellular structures like mitochondria and ribosomes.

Cell Structure

This page introduces the fundamental concepts of cell structure in GCSE Biology. It compares eukaryotic and prokaryotic cells, highlighting their key differences and similarities.

Eukaryotic cells, found in animals and plants, contain membrane-bound organelles. Prokaryotic cells, typically unicellular organisms, have a simpler structure. Both types share some common features like a cell membrane, cytoplasm, and ribosomes.

The page details specific organelles found in animal and plant cells:

• Nucleus: Contains DNA and is enclosed by a nuclear membrane
• Cytoplasm: A liquid where chemical reactions occur
• Cell membrane: Controls substance entry and exit
• Mitochondria: Site of aerobic reactions for energy production
• Ribosomes: Where protein synthesis takes place

Plant cells have additional structures:

• Chloroplasts: Site of photosynthesis
• Vacuole: Used for storage and cell rigidity
• Cell wall: Provides strength and is made of cellulose

Vocabulary: Eukaryotic cells have membrane-bound organelles, while prokaryotic cells are simpler, unicellular organisms.

Highlight: Both eukaryotic and prokaryotic cells have a cell membrane, cytoplasm, and ribosomes, but only eukaryotic cells have a nucleus and mitochondria.