Computer modelling software can be used to explore the internal components of cells (based on images generated by electron tomography)

• Click on the models below to explore the structures identified

Bacteria (Prokaryote)

Bacteria are prokaryotic cells, meaning they lack a nucleus and internal compartmentalisation (no membrane-bound organelles). Bacilli (e.g. E. coli) are a rod-shaped bacteria.

Animal Cell (Eukaryote)

Animal cells are eukaryotic (have a nucleus and internal compartmentalisation). They do not possess a cell wall and have small, temporary vacuoles (if any). The prevalence of certain organelles will be determined by the function of the cell (e.g. phagocytes have many lysosomes, while muscle cells have many mitochondria).

Plant Cell (Eukaryote)

Plant cells are eukaryotic (have a nucleus and internal compartmentalisation). They possess a cell wall made of cellulose and have a large, central vacuole (sap vacuole). Plant cells may have chloroplast if they are part of the photosynthesising tissue (i.e. leaf cells have chloroplasts, but root cells do not).

Phospholipid Bilayer

All cell membranes (both internal and the plasma membrane) are made up of a phospholipid bilayer. The phosphate heads face outwards towards the aqueous solutions (interstitial fluid and cytoplasm), while the fatty acid tails face inwards (held together by weak hydrophobic associations).

Nucleus

The nucleus is a double-membrane structure with pores. The nuclear membrane is continuous with the endomembrane system (ER network). Within the nucleus, the nucleolus is a dark region that is responsible for ribosome assembly.

Mitochondria

The mitochondrion is a double-membrane structure that has its own DNA (circular) and ribosomes (70S). The inner membrane is highly folded, which increases the surface area available for aerobic respiration (ATP production).

Chloroplast

The chloroplast is a double-membrane structure that has its own DNA (circular) and ribosomes (70S). Within the chloroplast are thin thylakoid discs, organised into stacks called grana. These are responsible for the absorption of light. The surrounding fluid is called the stroma.