Cells
Biology: Edexcel IGCSE, topic 2.1.1
Cell Components
Cells of living organisms contain organelles - small structures in the cytoplasm where chemical reactions happen (e.g. ribosomes, mitochondria, chloroplasts). The cells of all living organisms contain:
Cell membrane
- The cell membrane separates the interior (inside) of the cell from the environment outside.
- It is selectively permeable (it can control substances moving in and out of the cell).
Cytoplasm
- Cytoplasm is a jelly-like fluid that fills the cell.
- It is where most of the cell’s chemical reactions take place.
DNA
- DNA is the molecule that makes up the genetic material of cells.
- It contains the instructions for making cells and for all the cell's functions.
Ribosomes
- Ribosomes are organelles that are responsible for synthesising (making) proteins.
Enzymes
- Enzymes are known as biological catalysts; they speed up lots of the reactions that happen in cells, such as those involved in respiration.
Test yourself on Cells
What do ribosomes do?