Download Ch.7.4 Homeostasis Notes

Chapter 7.4 Notes
“Homeostasis and Cells”
Organisms can be a single cell in size.
To maintain homeostasis unicellular organisms grow, respond
to the environment, transform energy and reproduce.
Unicellular organisms can be prokaryotic and eukaryotic.
 Prokaryotic – bacteria, adaptable
 Eukaryotic – protists including algae, paramecia, and
amoeba
o Fungi – yeast
Multicellular organisms are composed of specialized cells that
work together and communicate to maintain homeostasis.
Cell specialization – a specific job a cell has within the organism
 The shape of a cell can determine the role it will have
within the organism.
Levels of organization within living things:
Cell
Tissue – a group of similar cells that perform a function
Organ – different types of tissue that work together to perform a
function
Organ system – different organs that work together
*specialization and interdependence are characteristics of living
things.
How cells communicate –
Cellular junctions – connections between cells that hold cells
together tightly
Chemical signals – molecules that move from one cell to
another
 The bonding site for these chemical signals is called a
receptor
o Receptors are either on the cell membrane or in
the cytoplasm