Cells are the basic units of life that contain all the necessary chemical reactions to maintain and reproduce life. They can be either prokaryotic, consisting of single-celled organisms like bacteria, or eukaryotic, having cells with a nucleus containing DNA. All eukaryotic cells have three main parts - a plasma membrane that separates the internal environment from the outside, cytoplasm containing organelles outside the nucleus, and a nucleus that acts as the cell's control center housing the chromosomes.

1. WHAT ARE CELLS?

2. WHAT ARE CELLS?
• Cells are the functional units of life, in which all of the chemical
reactions necessary for the maintenance and reproduction of life take
place.
• They are the smallest independent units of life.
• Cells are either prokaryotic or eukaryotic.
• All prokaryotes are independent, single-celled organisms (e.g.,
bacteria).
• All eukaryotes(“true nucleus”) have cells with a membrane-bound
nucleus containing DNA.

3. All eukaryotic cells have three basic parts
• 1. The plasma membraneis the outer boundary of the cell. It
separates the internal metabolic events from the environment and
allows them to proceed in organized,controlled ways.
• 2. Cytoplasm is the portion of the cell outside the nucleus. The
semifluid portion of the cytoplasm is called the cytosol. Suspended
within the cytosol are the organelles.
• 3. The nucleus is the cell control center. It contains the chromosomes
and is separated from the cytoplasm by its own nuclear envelope. The
nucleoplasm is the semifluid material in the nucleus.