Edexcel A (SNAB) A Level Biology:復(fù)習(xí)筆記3.1.1 Cell Theory

Category: A-level課程, 國(guó)際課程, 教材筆記, 福利干貨 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