cells, tissues and organs
the parts of a cell
all living things-organisms-are made of units called cells
cells can be very specialized, but some things are common to all types of cell
both animal and plant cells have three mains parts a cell surface membrane, cytoplasm, and a nucleus
the cell surface membrane is the outside part of the cell it controls how substances enter and exit the cell
the cytoplasm is inside the surface membrane it contains water and other substances such as sugar and salts
the nucleus contains the genetic material the dna this carries the coded instructions which control the activities of the cell
plant cells
in addition, plant cells have a strong cell wall this gives them a very regular shape they also have a special area that contains water they may also have parts called chloroplasts that contain chemicals that the plant needs