The nucleus contains DNA and the Nucleolus, which is where ribosome assembly begins. I chose the city hall because that is where the head of the city is.

The nucleolus is where ribosome assembly begins. I chose the mayors office because that is where bills or political motions are made.

I chose the guards because the Nuclear Envelope protects the nucleus just as guards protect city hall.

The rough ER process specific proteins just like the mail man picking up mail to be shipped.

The smooth E.R. is like manufactures lipids and hormones just like the Pittsburgh steel mills.

I chose a construction site to represent the ribosomes. In a ribosome the RNA is read and then the protein is constructed. In this picture the blue prints are read and then the building is built.

The golgi apparatus receives lipids and proteins, modifies them, packages them in vesicles, and then ships them. The same thing happens in a post office. Packages are modified, packaged, and then shipped off to their destination.

Vacuoles and vesicles store things in the cell. Vacuoles store food, nutrients, and even waste. Every plant cell has a central vacuole that holds water. Vesicles are temporary and are formed to bring things in or out of the cell. Vacuoles are like large storage units and the central vacuole would be the central storage unit. Vesicles are comparable mobile storage units.

Lysosomes move around the cell collecting and disposing of waste with digestive enzymes. They are like the trash trucks that collect, compact and dispose of waste.

The cytoskeleton connects different parts of the cell and helps to maintain cell shape. It allows the entire cell to move and helps organelles move throughout the cell. During cell division the microtubules in the cytoskeleton help move the chromosomes and divide the two cells. Similarly, roads connect different parts of the city and help define city limits. They also allow things to move throughout the city.

Centrioles assist in cell division by organizing the chromosomes. The centrioles are usually found near the nucleus. In a city the branches of government help organize laws and make the city run smoothly. Just like the two centrioles being near the nucleus, the branches of city government are near the capital.

Chloroplasts, organelles only found in plant cells, turn light into energy through photosynthesis. Similarly, the solar panels on the Pittsburgh "breathing" building use solar energy to power the building.

The mitochondria is the power house of the cell. Mitochondria are in animal and plant cells, and they are passed down through the mother. This means that all mitochondria can be traced back to one mitochondrial mother that lived millions of years ago. The mitochondria takes the energy stored in food and turns it into the chemical adenosine triphosphate (ATP). This is then used to power many of the functions that animals do on a daily basis.

The cell wall is the rigid and protective outer layer of a plant cell. It is beyond even the cell membrane. The cell wall is made of the strong substance cellulose which gives branches and leaves and stem's their shape. In a city the city limit defines the shape of the city on a map and it is protective of the city because the city limit is often patrolled by police.

The cell membrane is a semi-permeable membrane. This means it has allows certain substances in while keeping others out. The cell membrane has channels through it to allow substances in and out. An example of one such channel is an aquaporin which allows water in and out of the cell. Another way to cross the cell membrane is through protein pumps. Things cross the cell membrane in several ways. Facilitated diffusion, osmosis, and passive transport allow things to cross the membrane without the cell exerting any energy because the materials flow with the concentration gradient. Active and bulk transport such as endo, phago, pino, and exocytosis require cellular energy because they are mover material against the concentration gradient. In Pittsburgh the three rivers surrounding the city act as the cell membrane. The bridges act as the protein pumps and aquaporins. People and shipments cross these bridges but not before going through protective checkpoints on and off the Pennsylvania Turnpike. The Pittsburgh natives with Turnpike Fast Passes represent forms of passive transport because they are not checked entering and leaving the city. All of the visitors and shipments represent active transport because they are checked entering and exiting the city.