Cells and Microscopy

Cells: The Basic Units of Life

All living organisms are made up of cells, they are the basic unit of life.
There are two main types of cells: prokaryotic and eukaryotic.
Prokaryotic cells, found in bacteria and archaea, do not have a nucleus. Their DNA resides in a region called the nucleoid.
Eukaryotic cells, found in animals, plants, fungi, and protists, have a nucleus which houses their DNA.
All cells contain cytoplasm, a cell membrane, and ribosomes.

The nucleus controls the cell’s activities by controlling the production of proteins. It also contains the cell’s DNA.
The cytoplasm is a gel-like substance where the cell’s metabolic reactions occur.
The cell membrane controls what enters and leaves the cell.
The mitochondria are responsible for respiration and providing energy.
Ribosomes are sites of protein synthesis.
In plant cells, you will also find a cell wall, chloroplasts and a central vacuole.

Prokaryotic cells, compared to eukaryotic cells, are smaller and have fewer structures.
They have a cell membrane and cell wall and also have a further protective layer, the capsule.
They have plasmids, small rings of DNA.
They do not have a true nucleus, but they have a nucleoid where DNA resides.

Some cells in multicellular organisms become specialised, meaning they take on a specific role.
Specialised cells include sperm cells, nerve cells, and root hair cells in plants.
Each type has its own unique structure, relevant to its function.

Microscopes are crucial tools in biology to study cells.
There are multiple types of microscopes. The most common are the light microscope and the electron microscope.
The light microscope uses light and lenses to magnify an object and works well for viewing live organisms.
The electron microscope uses an electron beam, and can view much smaller structures, like the structures within a cell, with a higher resolution.
However, electron microscopes are more expensive and require more preparation of the sample.

Cell culture involves the distribution of cells in a lab, usually onto a flat surface in a dish.
It’s valuable for studying cell growth, response to drugs or the behaviour of cancer cells.
Sterile techniques are used to prevent contamination of the cultures.