Biology
Biology: Exploring Life
Biology is the scientific study of
life
Biological Hierarchy
of Organization:
Life can exist here
http://www.ux1.eiu.edu/~cfruf/images/bio
3002/els_le2.jpg
Hierarchy of Life; Organization levels
Molecules are atoms held together by chemical
bonds (ex: DNA, protein)
Organelles are membrane-bound structures
with specific functions for & w/in some cells
Cells are the smallest unit of life; separates the
environment with a membrane
Tissues are layers of cells to perform a specific
function
Organs are groups of tissues working together
to perform a specific function
Hierarchy of Life; Organization levels, cont’d
Organ Systems are organs grouped together to
perform a function
Organism is a living thing within a population
Population: the same species living within a
specific area
Community: many groups of different species
within an ecosystem
Ecosystem: contains biotic (living) factors &
abiotic (nonliving) factors within a specified
area/community
Biosphere: all ecosystems of the Earth
Hierarchy of Life; Organization levels, cont’d
• From most specific to general:
Atoms Molecules Organelles
Cells Tissues Organs Organ
Systems Organism Population
Community Ecosystem Biosphere
*Blue color denotes living/biotic
Cycle of Nutrients and Energy:
http://www.globalchange.umich.edu/globalchange1
/current/lectures/kling/ecosystem/zebra2.gif
Organism Interaction, Matter, and Energy
• An Ecosystem contains 3 categories of
organisms:
– Producers (autotrophic organisms like plants,
algae, and some bacteria): perform
photosynthesis (absorb H2O, CO2 & sunlight &
convert these to sugar and O2)
– Consumers (heterotrophic organisms like
animals): organisms that eat plants and other
animals. These take in O2 and release CO2, while
releasing waste into the environment.
– Decomposers (heterotrophic organisms like
bacteria and fungi) that break down wastes and
dead/decomposing organisms, while recycling
matter into the environment (which the producers
use).
Organism Interaction, Matter, and Energy, Cont’d
• Ecosystems have 2 major processes: Recycling
chemical nutrients and energy flow.
• Recycling chemical nutrients: O2, CO2, H2O, etc. go
from the air and soil to producers to consumers to
decomposers and then back to the air and soil.
These are recycled!
• Energy Flow: solar energy is absorbed by producers
& converted to chemical energy thru photosynthesis.
– Chemical energy is passed thru many organisms
(consumers: primary to secondary, etc) and then finally to
decomposers.
– At every pass, some energy is LOST as heat.
– Energy flows THROUGH the ecosystem (enters as light;
exits as heat).
Cells, the structural & functional unit of life
• The cell is the basic unit of life, the lowest
level of structure at which the properties of
life emerge. These correlate structure =
function!
• The cell:
– Regulates its internal environment (homeostasis)
– Takes in & uses energy
– Responds to its environment
– Develops & maintains a complex organism
– Reproduces (give rise to new cells)
Cells, the structural & functional unit of life, Cont’d
Characteristics of a Cell:
• Enclosed in a membrane (which regulates the
flow/regulation of materials in and out of the cell)
• Contains DNA (genetic material), cytoplasm,
ribosomes
2 types of cells:
• Prokaryotic Cell (Kingdoms Archaebacteria and
Eubacteria): bacteria; small and simple cells
• Eukaryotic Cell (All other Kingdoms): plants,
animals, protists, and fungi.
– Have organelles (functional compartments with specific
functions)
– Have a nucleus that contains DNA
Prokaryote:
Eukaryote:
http://www.ichristianschool.com/biology/images/prokaryote.jpg
http://faculty.uca.edu/~johnc/eukaryote.jpg
Unity of Life
• The continuity of life is based
on ALL living things have
DNA (genetic material).
• Genes (inheritable material) are
made up of DNA sequences
– DNA is 2 chains coiled together
to form a double helix (structure)
– Nucleotides= building blocks;
these contain nitrogenous
bases attached: adenine (A),
thymine (T), guanine (G), or
cytosine (C).
• All forms of life contain the
same genetic code; the
sequences (order) is
different. This results in
different genes.
http://www.scq.ubc.ca/wp-content/dna.gif
Unity of Life, Cont’d – CHARACTERISTICS OF LIFE:
In addition to Genes, all organisms have:
• Order (level of organization)
• Metabolism (all chemical reactions)
• Regulation (a.k.a. homeostasis, or control of the
internal environment to sustain life)
• Growth (increase in size)
• Development (change in form)
• Energy processing (ability to use & transform, or
transduce, energy)
• Response to Environment (both internal & external
stimuli)
• Reproduction (make more like themselves)
• Evolutionary Adaptation (traits that are best suited to
the environment that are passed on to the offspring;
ie. camouflage, spots, etc)
Diversity of Life – Classification of organisms
• A species is the smallest category of
organisms (most specific)
– share the most common characteristics
– can reproduce with each other.
• Taxonomy is the branch of Bio which names
& classifies organisms according to
characteristics and similarities
– molecular, genetic, biochemical, morphological,
evolutionary phylogenies/histories, etc.
This is completed from broadest category to most
specific:
Domain Kingdom Phylum Class
Order Family Genus Species
http://upload.wikimedia.org/wikipedia/commons/9/96/S
cientific_classification.png
http://www.lesley-smitheringale-fine-art.com/wpcontent/uploads/2008/05/atlas-moth-scientific-classification.jpg
There are 3 Domains: Domain Bacteria or Eubacteria, Domain
Archaea, Domain Eukarya
• Domain Bacteria or Eubacteria (have peptidoglycan in their cell
walls)
• Domain Archaea (live in extreme environments, like hot or salty
places, or anaerobic environments)
– BOTH Bacteria and Archaea are prokaryotic, are bacteria, are
unicellular & microscopic, and are found in Kingdoms
Archaebacteria and Eubacteria.
• Domain Eukarya
– Include all eukaryotic organisms (have organelles & a nucleus).
– Include protists (Kingdom Protista). These are uni or multicellular.
Ex. Include algae and protozoans
– Include plants (Kingdom Plantae), which have a rigid cell wall and
perform photosynthesis.
– Include animals (Kingdom Animalia) which lack a cell wall and
must consume food
– Include fungi (Kingdom Fungi) which are yeast, mushrooms and
molds that decompose dead organisms.
– Protista, Plantae, and Fungi are generally separated by their
modes of nutrition.
Domain Bacteria:
Electron Micrograph of
E. Coli
http://www.foxnews.com/images/250204/0_61_bac
teria_e_coli.jpg
Domain Arachaea:
Image of
Methanococcus
jannaschii
http://www.biology.iupui.edu/biocourses/
n100/images/dmethanopyrus.jpg
A Micrograph of
Euglena (Protist):
http://faculty.clintoncc.suny.edu/faculty/Michael.Gregory/
files/Bio%20102/Bio%20102%20lectures/Evolution,%20
Speciation,%20Taxonomy/specia12.gif
Plant: Palm Tree
http://www.untiredwithlovi
ng.org/palm_tree_2.jpg
Fungi: Death Cap,
Death Angel Mushroom
http://www.gencat.cat/especial/bolets/i
mg/toxics/farinera_borda1.gif
http://www.biologyreference.com/
images/biol_04_img0381.jpg
Animal: Bull Shark
http://animals.nationalgeographic.com/static
files/NGS/Shared/StaticFiles/animals/image
s/primary/bull-shark.jpg
Evolution Explains the Unity & Diversity of Life
• Darwin wrote On the Origin
of Species by Means of
Natural Selection which
supported the idea of
evolution = species alive
today are descendants of
ancestral species (a.k.a.
‘descent with
modification’).
• This means descent from a
common ancestor. This
supports the unity of life.
• Darwin’s idea supported
the diversity of life
(modification as species
diverged).
http://www.goodschist.com/wp-content/gallery/charlesdarwin/Darwin_age29.JPG
Darwin recognized that variations existed
within organisms.
– These enhance their ability to survive AND
reproduce (this is the essence of evolution
by means of natural selection).
• These successful adaptations are the
result of evolution, the process of
change over time which has
transformed life on Earth.
Evolution Explains the Unity & Diversity of Life, Cont’d
• Darwin proposed that evolution occurred
through Natural Selection (NS):
– Recognized (observed) that w/in a population,
variations exist AND in many cases more organisms
were produced than could survive (to produce their
own offspring); this was an overproduction of
offspring.
– From these observations, he suggested that the
individuals who were likely to survive AND
reproduce were best suited to the environment;
they inherited the best traits and would pass these
traits on to their offspring.
– Overtime, the best suited (or favorable) traits would
accumulate within a population. This could
eventually lead to a new species.
Evolution Explains the Unity & Diversity of Life, Cont’d
• The environment ‘selects’ for individuals w/certain
traits meaning there is an unequal reproductive
success. This is Natural Selection (NS).
• The product of NS = evolutionary adaptation, or the
accumulation of favorable traits in a population over
time.
• NS is an editing process that works on heritable
variations which are exposed to environmental
factors that favor reproductive success.
• Major alteration of a species could occur from many
small changes w/in a population. Darwin proposed
that a new species could arise due to these gradual
changes over long periods of time.
Scientific Method – terms that have different meanings
in Science versus mainstream use:
• Science means “to know.”
“Science can neither prove nor disprove the existence
of a God or supernatural power- for such questions are
outside the bounds of science.”
• A hypothesis is a possible (plausible) explanation
based on observation (that can be tested).
Mainstream use : an “educated guess”
Theories in science:
• A theory is a hypothesis that has been tested
repeatedly and is generally regarded as true.
Examples: Theory of Evolution, Theory of Relativity,
Atomic Theory, Cell Theory.
Mainstream use: just an “idea”
The Evolution Connection
Evolution is the CORE theme in biology.
• There are many differences (and similarities) in DNA
among individuals, populations, and species; this
reflects evolutionary change.
• Through the Human Genome Project (HGP),
scientists have been able to ID & construct the DNA
base sequences of many species.
– allows comparative & functional genomics (the ability to
identify common genes, search for new medical treatments,
and more using DNA technology).
• DNA differences in humans is used in forensics: this
is DNA fingerprinting or DNA profiling and is used to
convict or exonerate, determine paternity, or identify
remains.
Evolutionary knowledge can help
scientists in the understanding:
• Vaccinations
• HIV drugs
• virus evolution
• the development of antibiotic-resistant
bacteria & pesticide-resistant crops
• how to help endangered species