<human>:  Why are there two ribosomes in a cell?
<bot>: Ribosomes are the site of protein synthesis in a cell. They are composed of RNA and protein. There are two ribosomes in a cell because they are specialized to synthesize different proteins. The small ribosome is responsible for synthesizing proteins that are needed for cell maintenance and growth, while the large ribosome is responsible for synthesizing proteins that are needed for cell division.