unit 2 vocab Flashcards
tissue
a group of similar cells that work together to perform a particular function
organ
a group of tissues that work together to perform a particular function
organ system
several organs that work together to perform a particular function
magnification
how many times larger an image is than the actual object.
electron micrograph
an image made using an electron microscope
bacteria
unicellular organisms whose cells do not contain a nucleus
prokaryotic cells
cells with no nucleus; bacteria have prokaryotic cells
plasmids
small, circular molecules of DNA, found in many prokaryotic cells in addition to the main, much larger circle of DNA
cells
the smallest units from which all organisms are made
cell membrane
a very thin layer surrounding the cytoplasm of every cell; it controls what enters and leaves the cell
partially permeable
allows some molecules and ions to pass through, but not others
cell wall
a tough layer outside the cell membrane; found in the cells of plants, fungi and bacteria
fully permeable
allows all molecules and ions to pass through it
cytoplasm
the jelly-like material that fills a cell
metabolic reactions
chemical reactions that take place in living organisms
