Biology: Science of Life
• What do Biologists do?
– Study past, present and future life
• Interactions, structures, functions
• Solve biological problems
– Agriculture
– Disease
– Conservation/Remediation to maintain diversity of life
What is life?
• We decide
• Has or once had the
following
characteristics:
– 1+ cells
– Organized/Complex
– Grows and develops
– Maintain
Homeostasis
– Reproduces
– Responds to Stimuli
– Uses Energy
– Adaptations Evolve
• 1+ cells
– The cell is the basic unit of life
– unicellular v. multicellular v. acellular
• Organized/Complex
– Chemical complexity for structure and function
– Structural organization: Atoms molecules cells
tissues organs organ systems organism
(assuming multicellular)
• How do we amend this sequence if the organism
is unicellular?
• Homeostasis
– Regulate internal conditions
ex: temp, water, blood sugar
• Grow/develop
– Growth: addition of mass
–Increase cell size and/or increase cell
number
– How does a unicellular grow; a multicellular?
– Development: change over time
–Go through stages of maturity
• Respond to Stimuli
– Able to process and react to internal/external environ.
–Stimulus response
• Use Energy
– Get/make food (chemical energy) to fuel metabolism,
convert energy (ATP) to power processes, maintain
chemical disequilibrium
• Categorizations for how “food” is obtained by life:
– Autotroph (chemoautotroph or photoautotroph)
– Heterotroph (by ingestion or by absorption)
More on Autotrophy…
There are two general processes:
•___________________
ouse sun as energy needed to make food
•____________________
ouse chemicals as energy to
drive “food making” process
oHydrothermal deep sea vents
• Reproduce
– Species = group of organisms that can interbreed
to produce viable (fertile) offspring
– What about individuals that cannot bear offspring??
• Adaptations/Evolution
– Change in inherited traits (genetics) in a
population/species over time (generations) due to
reproduction
– Genetic variation is a generally good thing for species
survival
– Individuals do not biologically evolve!
• Cells:
Details on Characteristics
Unicellular
Multicellular
1st life forms
Evolved later
1 cell
More than one cell
All bacteria, most
protists, some fungi
All animals, all plants,
some fungi
GROW by cell
enlargement only
GROW by cell
enlargement and cell
division
REPRODUCE mainly by
making specialized cells
that combine sexually
REPRODUCE by cell
division (asexual
reproduction/cloning)
• REPRODUCTION:
Details on Characteristics II
Asexual
Evolved first
Sexual
Evolved later
Unicellular organisms
divide to make more
identical unicellulars
One “parent” –
contributes 100% of
genetic info
Make a clone – no genetic
variation between
generations
Multicellular organisms
use meiosis to make
sperm/egg
Two “parents” – each
contribute 50% of genetic
info
Genetically different
offspring – more variation
in population – GOOD for
survivability/evolution
• Energy use
Details on Characteristics III
Autotrophs
Heterotrophs
BOTH versions of organisms convert “food” energy
into ATP energy to power their cellular processes!!
All plants, some
All animals, All fungi, some
bacteria, some
bacteria, some protists (NOTE:
protists
some plants can do this too!
“carnivorous plants –VFT!)
AKA “producers”
AKA “consumers”
Make own food
Eat other organisms or the
products of other organisms
Two versions:
• Photosynthesis
• Chemosynthesis
• Adaptation/Response
Details on Characteristics IV
Adaptation (evolution) Response (to stimuli)
Long-term
Short-term
Population response to
changing environmental
conditions
More genetic variability
in the population = the
better able the
population can adapt
EX: adaption as a result
of changing climate –
thicker fur
Immediate feedback to
stimuli
EX: response to changing
temperatures – burrow,
put on a coat
Life vs. Viruses
• Bacteria (2 kingdoms), protists, fungi, plants and animals
are living; viruses are NOT
• living things exhibit ALL characteristics of life
• NOTE: if you need a microscope to see, it is called a
“microbe” or “microorganism”; if it causes disease we
called a “pathogen”.
– MOST bacteria do not cause human illness!
Viruses:
 are acellular
 do not (generally) reproduce themselves
 do not use energy/ have a metabolism
Chapter 1.1 Big Concepts
• Understand that there are 6 kingdoms (big categories!) of life
and viruses are not included in any of them
• Reproduction of life can be sexual or asexual
• Obtain energy via heterotrophy and/or autotrophy
(chemoautotroph, photoautotroph)
• Evolution results in adaptations in a population
• Viruses are acellular; Life consists of prokaryotic or eukaryotic
cells and is unicellular or multicellular
• Living things can regulate their internal conditions
(homeostasis)