Label and give the functions of the main features of prokaryotic cells.

Explain the differences between plant and animal cells seen under an optical microscope.

Organisms such as bacteria are called prokaryotes. They are made up of prokaryotic cells that lack many of the structures seen in plant and animal cells. They have no membrane-bound nucleus – the genetic material is a single strand coiled up in the centre to form a nucleoid. Sometimes there are separate small pieces of genetic material called plasmids. The cytoplasm contains enzymes, ribosomes and food storage granules but there is no endoplasmic reticulum, no Golgi apparatus, no mitochondria and no chloroplasts. Respiration takes place on a special piece of plasma membrane called a mesosome. Bacteria that photosynthesise have a form of chlorophyll but no complex structures to hold it. Bacteria also have short hair-like structures called pili which they use to stick onto surfaces and some have whip-like flagella which they use to move through liquids.

Eukaryotic Cells

Animals, plants, fungi and protoctists (single-celled organisms such as Amoeba) all have cells containing membrane-bound organelles, unlike prokaryotic cells. These include the nucleus, mitochondria, endoplasmic reticulum, lysosomes, Golgi apparatus, vacuoles and chloroplasts in plants.

Using an optical (light) microscope it is possible to tell the difference between the animal and plant eukaryotic cells. What differences can you see between plant and animal cells under the optical microscope?

Animal cell under an optical microscope

Plant cell under an optical microscope

Cell Biology Links

Microbiology Links

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