Organization of Matter
• Elements: all matter is composed of
substances called elements (ex: carbon,
nitrogen, gold, silver, etc)
• Atom: the smallest unit of matter in an
element (ex: an atom of carbon, nitrogen, etc)
• Molecules: two or more atoms bonded
together. (ex: 1 carbon atom + 2 oxygen
atoms = carbon dioxide)
• MORE ABOUT ELEMENTS, ATOMS AND
MOLECULES IN THE NEXT LECTURE!
Organization of Matter
• Cell: basic unit of living organisms
– Contains simple and complex ORGANIC molecules
– Definition of “Organic”: a molecule that contains
• Tissues: a group of similar cells
• Organs: collection of tissues that serve a
• Organ systems (ex: CV system)
Organization beyond the
• Species: organisms of same type capable of
• Population: group of organisms of same species
living in a given area
• Community: collection of populations of
DIFFERENT species that interact with one another
• Ecosystem: a community and its nonliving
• Biosphere: entire surface of Earth, including living
and nonliving components
What is science?
• “Organized enterprise that gathers knowledge
about the world and condenses it into
testable laws and principles.”
• Biologists always want to answer questions,
also known as “scientific inquiry”.
Scientific Inquiry is based on a small
number of assumptions
• Natural Causality: all events can be traced to
• Natural Laws are timeless: always been that way
and law applies everywhere (ex: gravity,
• People are able to perceive and measure events.
These perceptions/measurements provide us
with reliable objective information about the
• Judgements about these events can differ as a
result of cultural/religious beliefs (ex: evolution)
So how do biologists study life?
• Answer: the scientific method!
• Method for making observations of specific
phenomena and searching for the order that
underlies this phenomena
• Example here:
Observation & Question
• Maggots can be seen on rotting meat left out
after a few days.
• It was thought that the maggots came FROM
the meat. (spontaneous generation).
• However, Redi also saw flies swarming on the
• Question: COULD THE FLIES BE THE SOURCE
OF THE MAGGOTS?
Hypothesis & Prediction
• Hypothesis: A supposition (guess), based on
observations, that is offered as an answer to
the question or explanation for the observed
• To be useful, hypothesis must lead to a
prediction. Expressed as if….then.
– Ex: If the maggots came from the flies, then
keeping the flies off the meat will prevent
Experiment and Observation
• Experiments require controls: situations that
keep untested variables constant
– Put one piece of meat in an airtight container
– Have one piece of meat left out (control)
– All other variables are the same
– (If he put one piece of meat in a container AND
put that container in a bucket of ice, then he
would be changing two variables.)
Example in every day life
• Car won’t start.
• Battery dead?
• If battery dead, then car will start with new
• Change battery (BUT DON’T CHANGE
ANYTHING ELSE – STARTER, IGNITION COIL)
• Car starts…it was the battery!
Use in medicine
• Testing new drugs
• Always a control and experimental group (try to get a
large, broad experimental group so results can be
applied to the WHOLE population)
• But people differ in many environments (nutrition level, population density, access
to clean water, etc). Best weapon against sampling error is large experimental
• Placebos often used (fake pills)
• Experiments can also be
– Double blind
To prevent bias
• After experiment is done, then either
– Accept hypothesis
– Do not accept hypothesis (reject)
• Accepted hypotheses must be repeatable and
testable by many different scientists. If it
continues to be accepted, eventually may
become a common scientific theory.
• If rejected, scientists may re-examine method
and re-test with different parameters
• As a result of scientific method, we now have
many scientific theories: a general explanation
for important natural phenomena that has
been EXTENSIVELY TESTED AND
REPRODUCED. Scientists believe these
theories to be fact.
• EX: law of gravity, atomic law, cell theory.
Cell Theory (COVERED Extensively
in lecture 4)
• The cell is the basic unit of life.
• Cells have elaborate structures:
– Genes: more about DNA later
– Organelles: structures that perform specific
functions (obtain energy, movement, making
– Plasma Membrane
What else characterizes living things?*
• 1.) living things made of cells
• 2.) organisms maintain homeostasis (body temp, etc.) Energy
is used to maintain homeostasis.
• 3.) living things respond to stimuli
• 4.) Living things acquire materials (to grow and reproduce)
• 5.) Living things grow
• 6.) Living things reproduce themselves
• 7.) Living things have the capacity to evolve
• WE HAVE TO HAVE A WAY OF CATEGORIZING ALL OF THE LIFE
FORMS ON EARTH.
• 3 domains:
• First 2 are procaryotes (no nucleus-genetic
material in cytoplasm) , made of simple, single
• Eukarya has bodies composed of one or more
complex cells. They are eucaryotes (membrane
enclosed sac containing cell’s genetic material)
Last way to categorize life*
(how organisms get energy)
• Autotrophs (Arch, bact, some protists)
– Self feeding: photosynthesis
– Convert inorganic carbon (CO2) to carbs, fats and
proteins (organic carbons) to be used by them or
ingested by heterotrophs
• Heterotrophs(arch, bact, and eukarya)
– Other feeding: need to eat other organisms to get
energy. Cannot make their own carbs, fats,
proteins. More about how WE get energy in