Cells Vocabulary Cells – building blocks of life. Tissues – a group of cells that work together as a team. Organs – a group of tissues working together to perform a specific job Organ system – a group of organs that work together to perform particular jobs. An example is the digestive system. Vocabulary Organism – anything that can live on its own. Unicellular – single cell living on its own. Multi-cellular – group of cells that can only exist when they are together. Vocabulary Population – a group of organisms that are of the same kind and that live in the same area. Communities – 2 or more different populations that live in the same area. Ecosystems – the community and all nonliving that affect it, such as water, soil, rocks, temperature, and light. Vocabulary Cell membrane – acts as a barrier between inside of the cell and the cell’s environment. It also controls the passage of materials into and out of the cell. Organelles – chemicals and structures that enable the cell to live, grow and reproduce. Cytoplasm – cellular fluid surrounding a cell’s organelles. Nucleus – the membrane covered organelle found in eukaryotic cells; contains the DNA and serves as a control center for the cell. Eukaryotic vs. Prokaryotic cells Eukaryotic – a cells contains a nucleus and a complicated internal structure. Has a nucleus Membrane-covered organelles Linear DNA Complex cell All other cells Prokaryotic – world smallest cells and they do not have a nucleus . DNA is one long, circular molecule shaped like rubber band. No nucleus No membrane –covered organelles Circular DNA Simple cell Bacteria