7.4 homeostasis and cells - plainfield east high...
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Lesson Overview Homeostasis and Cells
THINK ABOUT IT
What’s the smallest part of any living thing that still counts as being
“alive?”
Can we just keep dividing living things into smaller and smaller parts,
or is there a point at which what’s left is no longer alive?
As you will see, there is such a limit. The smallest living unit of any
organism is the cell.
Lesson Overview Homeostasis and Cells
The Cell Theory
Soon after the invention of the microscopek, observations were made
by scientists that made it clear that cells were the basic units of life.
In 1838, German botanist Matthias Schleiden concluded that all plants
are made of cells.
The next year, German biologist Theodor Schwann stated that all
animals were made of cells.
In 1855, German physician Rudolf Virchow concluded that new cells
could be produced only from the division of existing cells, confirming a
suggestion made by German Lorenz Oken 50 years earlier.
Lesson Overview Homeostasis and Cells
The Cell Theory
These discoveries are summarized in the cell theory, a fundamental
concept of biology.
The cell theory states:
-All living things are made up of cells.
-Cells are the basic units of structure and
function in living things.
-New cells are produced from existing cells.
Lesson Overview Homeostasis and CellsTHINK ABOUT IT
The diversity of life is so great that
you might have to remind
yourself that all living things are
composed of cells, use the same
basic chemistry, and even
contain the same kinds of
organelles.
This does not mean that all living
things are the same. Differences
arise from the ways in which
cells are specialized and the
ways in which cells associate
with one another to form
multicellular organisms.
Lesson Overview Homeostasis and Cells
Multicellular Life
The cells of multicellular organisms are
interdependent, and like the members of a successful baseball
team, they work together.
In baseball, players take on a particular role, such as pitcher, catcher,
infielder, or outfielder. Messages and signals are sent and understood by
teammates and coaches to play the game effectively.
Cells in a multicellular organism work the same way.
The cells of multicellular organisms become
specialized for particular tasks and communicate
with one another in order to maintain homeostasis.
This is referred to as Division of Labor.
Lesson Overview Homeostasis and Cells
Cell Specialization
The cells of multicellular organisms are specialized, with different cell
types playing different roles.
Some cells are specialized to move, others to react to the environment,
and still others to produce substances that the organism needs.
No matter what the role, each specialized cell contributes to the overall
homeostasis of the organism.
Lesson Overview Homeostasis and Cells
Specialized Animal Cells
Particles of dust, smoke, and bacteria are part of even the cleanest air.
Specialized animal cells act like street sweepers to keep the particles
out of the lungs.
These cells are full of mitochondria, which provide a steady supply of
the ATP that powers the cilia on their upper surfaces.
Lesson Overview Homeostasis and Cells
Levels of Organization
The specialized cells of multicellular organisms are organized into
tissues, then into organs, and finally into organ systems.
Cell: The smallest living unit of any organism
Lesson Overview Homeostasis and Cells
Levels of Organization
Tissue: a group of similar cells that performs
a particular function.
Lesson Overview Homeostasis and Cells
Levels of Organization
Organ: many groups of tissues work together
to perform complicated tasks.
Each type of tissue performs an essential task to help the organ
function.
In most cases, an organ completes a series of specialized tasks.
Lesson Overview Homeostasis and Cells
Organ system: a group of organs that work
together to perform a specific function
For example, the stomach, pancreas, and intestines work together as
the digestive system.
Levels of Organization
Lesson Overview Homeostasis and Cells
5.Organism