Download Hey! What exactly is LIFE anywaze?

CHARACTERISTICS OF LIVING THINGS
*Caveat: There is ongoing discussion among biologists as to what this
list should be. If you would like to have an opinion…you’ve gotcherself a
bucket-o-research to do
There are six characteristics that all
living things share*:
1. Made of Cells (thus…have DNA)
2. Obtain & Use Energy
3. Grow & Develop (Adapt & Evolve)
4. Respond to Stimuli (the environment)
5. Reproduce
6. Composed of certain chemicals
CELLULAR ORGANIZATION
• Cells are the basic building blocks of life…of it’s
alive…it’s made of cells.
• Every living thing is composed of one or more
cells.
• All cells have DNA as some point in their lives,
so…all living things have DNA)
• Organisms (that’s a living thing) can be singlecelled or made of many cells.
• Viruses aren’t made of cells…guess
what…they’re not alive. Too bad for them…they
can’t get into the movies or play the drums…as far
as I know anyway.
Obtain & Use ENERGY
• Metabolism is the term that refers to all of
the activities that go on within a single cell
or an entire organism.
• Energy is required in order to carry out all
of these cellular activities. ATP!
• Metabolic processes include making food,
breaking down food, moving materials in
and out of cells, and building cells and their
components (parts). It’s a lot of
work…teenaged cells are lazy…look for
them on the couch watching TV…tragic 
GROW AND DEVELOP
• All living things grow at some period of their
lives.
• Unicellular (single-celled) organisms simply grow
larger.
• Multi-cellular organisms (made of many cells)
grow by increasing their number of cells.
• Many organisms go through stages of
development. Some just a few…others have
many.
• Some scientist thing that
evolvability/adaptability is another
characteristic that should be included
Response To Environmental Stimuli
• All living things encountering a change in their
environment will respond to that change.
• Some responses are drastic and some are more
subtle…you can’t even see it happen.
• If you hear a loud noise you might jump…BOO!
See…calm down now. That’s a response.
• A plant might grow toward a light source…that’s a
response too, but you can’t see it happening. Go
ahead try to frighten a plant…it’ll ignore you and
you’ll just look silly.
• A stimulus can be: gravity, light, chemicals, vibration, sound,
temperature, electricity, etc.
REPRODUCE
• All organisms make other
organisms like themselves.
• Some living things reproduce
asexually, others
sexually…some…both…no kidding!
• Asexual Reproduction – single
parent produces offspring
(fission, budding). Offspring is
genetically identical to the
parent.
• Sexual Reproduction– two parents
required for reproduction
(conjugation) and offspring are a
combination of genetic material
from both.
A word about…Certain Biological
Molecules (CHEMICALS)
1. Carbohydrates – made of sugars, used for energy
2. Proteins-made up of amino acids. Some are
structural (for building) and some are enzymes
(needed for chemical reactions).
3. Lipids, fats, and oils – long-term energy storage
and cell membrane construction
4. Nucleic Acids (DNA & RNA)– provide the cell’s
genetic instructions; also needed to make proteins.
5. Starburst (Cherry only)- needed to rot your teeth
and make you all hyper from too much
sugar…seriously…why are you writing this down?
If We Decide You’re Alive…Then
What?
• Well…you’ll (any organism actually) need
four basic things:
1. Water: Almost ever living thing consists of
about 70% water. It’s needed for most
chemical reactions that take place within
an organism…and there are A LOT of
them…reactions, that is 
2. A Source of Energy: These are called nutrients
(some of those chemicals we talked about). You can
make your own (if you’re an autotroph…such as
most plants), or…you can eat another
organism…your choice. Well…not really.
3. Maintain Homeostasis: Wow! That’s a big word!
So, basically it means that organisms maintain their
internal conditions (like temperature, respiration,
blood pressure…in vertebrates). So like, if your
body is hot…you sweat and that cools you off (that’s
a simple example).
4. Physical Space: All organisms need someplace
to exist. Don’t confuse this with “shelter!” There
are plenty of living things that live in some crazy
rough places like The Dead Sea, deserts, The Poles,
boiling hot springs, and deep sea hydrothermal vents.
Those are some crazeeee conditions, and shelter?
That just ain’t happenin’
So…there you have it…
6 Criteria for Living Things and 4 Basic
Needs