Edexcel A (SNAB) A Level Biology:复习笔记3.1.1 Cell Theory

Category: A-level课程, 国际课程, 教材笔记, 福利干货 Date: 2022年11月8日下午3:56

Until microscopes became powerful enough to view individual cells, no-one knew for certain what living organisms were made from
A scientist called Robert Hooke is thought to be the first person to view cells, using the term 'cell' to describe these newly discovered structures
Matthias Schleiden and Theodor Schwann were two other scientists who studied animal and plant cells
- In 1837 they came up with the idea that all living organisms are made of cells
- This idea is known as ‘cell theory’
- The cell theory is a unifying concept in biology, meaning that it is universally accepted
Cell theory includes three main ideas
- All living organisms are made up of one or more cells
- Cells are the basic functional unit in living organisms
- New cells are produced from pre-existing cells

The cells of all living organisms share some common features
- Cell surface membrane
- Cytoplasm
- DNA
- Ribosomes
Beyond these common features different cell types contain different structural elements and combinations of organelles, e.g.
- Prokaryotic cells have no internal membranes and smaller ribosomes
- Eukaryotic cells have several internal membrane-bound organelles and larger ribosomes
When examined under a microscope it is possible to see the ultrastructure of different cell types
- Cell ultrastructure refers to the internal structures of the cell