The Characteristics of Life
Biology is the
study of the
living world
What does it
mean to be
living?
To be
considered
living all of the
characteristics
of life must be
met.
All life is made of cells
– Cell is the smallest unit that is considered living
– Organisms can be multicellular or unicellular
– Cells of multicellular organisms have a specific
structure and function
All life contains DNA
– All living cells have DNA which contains genes
– A gene is a segment of DNA that provides instructions
to the cell on making proteins
– The proteins produced determine your genetic traits
– Different traits
are caused by
different
proteins
which is
caused by a
different DNA
sequence.
All life transforms energy
Metabolism: the chemical reactions that occur within a
living organism in order to maintain life.
– Photosynthesis: The process where cells convert
energy from the sun into sugar.
– Cellular Respiration:
The process where
cells convert energy
from sugar into a
form of energy the
cell can use.
All life maintains internal balance
• Homeostasis: the ability to maintain a constant internal
environment in response to environmental changes.
– Cells can only function properly in the correct
environment
– How does your body respond to being too cold?
– How does
your body
respond to an
increase in
sugar?
All life reproduces
• Reproduction: the process where new organisms
(offspring) are produced from parent organisms.
– Asexual reproduction: identical cells are created
through the process of mitosis and cell division
– Sexual Reproduction:
non-identical sperm
and egg cells are
created through the
process of meiosis.
– Only organisms
capable of sexual
reproduction can
evolve.
All life responds to its environment
• Ecology: the study of interactions between
organisms and their environment.
– Everything in nature is interconnected
– Manipulating a single variable in an environment can
have unforeseen consequences
All life must be able to evolve
• Evolution: a genetic change in a population that is
inherited over several generation.
– The genetic change increased the organisms ability to
survive and reproduce in the environment.
– Populations who cannot evolve go extinct when the
environment changes.
– Evolution occurs
when individuals
beneficial genetic
traits survive and
reproduce and
individuals without
the traits die.