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Themes and Concepts of Biology

•  Properties of Life
•  Levels of Organization of Living Things
•  The Diversity of Life
•  Branches of Biological Study

More to come
More subject specific images will be added to this resource page.

Properties of Life
•  Order can include highly organized structures such as cells, tissues, organs, and organ systems.
•  Interaction with the environment is shown by response to stimuli.
•  The ability to reproduce, grow and develop are defining features of life.
•  The concepts of biological regulation and maintenance of homeostasis are key to survival and define major properties of life.
•  Organisms use energy to maintain their metabolic processes.
•  Populations of organisms evolve to produce individuals that are adapted to their specific environment.

Levels of Organization of Living Things
•  The atom is the smallest and most fundamental unit of matter, and the bonding of at least two atoms or more form molecules.
•  The simplest level of organization for living things is a single organelle, which is composed of aggregates of macromolecules.
•  The highest level of organization for living things is the biosphere; it encompasses all other levels.
•  The biological levels of organization of living things arranged from the simplest to most complex are: organelle, cells, tissues, organs, organ systems, organisms, populations, communities, ecosystem, and biosphere.

The Diversity of Life
•  The three major Domains of Life include: Domain Bacteria, Domain Eukarya and Domain Archaea.
•  Domain Bacteria and Domain Archaea include prokaryotic cells that lack membrane-enclosed nuclei and organelles.
•  Domain Eukarya include eukaryotes and more complex organisms that contain membrane-bound nuclei and organelles.
•  Carl Woese defined Archaea as a new domain and constructed the phylogentic tree of life which shows separation of all living organisms.
•  The phylogenetic tree of life was constructed by Carl Woese using sequencing data of ribosomal RNA genes.Therefore, genetics classification surpassed morphological cataloguing, which was the traditional way of organizing living beings.

Branches of Biological Study
•  Biology is broad and focuses on the study of life from various perspectives.
•  The branches and subdisciplines of biology, which are highly focused areas, have resulted in the development of careers that are specific to these branches and subdisciplines.
•  Branches of biological study include microbiology, physiology, ecology and genetics; subdisciplines within these branches can include: microbial physiology, microbial ecology and microbial genetics.


Key terms
•  chemotaxis the movement of a cell or an organism in response to a chemical stimulant
•  DNA a biopolymer of deoxyribonucleic acids (a type of nucleic acid) that has four different chemical groups, called bases: adenine, guanine, cytosine, and thymine
•  extremophile an organism that lives under extreme conditions of temperature, salinity, etc; commercially important as a source of enzymes that operate under similar conditions
•  forensic Relating to the use of science and technology in the investigation and establishment of facts or evidence in a court of law.
•  gene a unit of heredity; the functional units of chromosomes that determine specific characteristics by coding for specific proteins
•  genetic engineering the deliberate modification of the genetic structure of an organism
•  macromolecule a very large molecule, especially used in reference to large biological polymers (e.g. nucleic acids and proteins)
•  molecule The smallest particle of a specific compound that retains the chemical properties of that compound; two or more atoms held together by chemical bonds.
•  phototaxis The movement of an organism either towards or away from a source of light
•  phylogeny the evolutionary history of an organism
•  polymerization The chemical process, normally with the aid of a catalyst, to form a polymer by bonding together multiple identical units (monomers).

Although no two look alike, these kittens have inherited genes from both parents and share many of the same characteristics.

Adaptation in the flat-tailed horned lizard
This lizard exhibits a flattened body and coloring that helps camouflage it, both of which are adaptive traits that help it avoid predators.

Response to Stimuli
The leaves of this sensitive plant (Mimosa pudica) will instantly droop and fold when touched.After a few minutes, the plant returns to normal.

Multicellular Organisms
A toad represents a highly organized structure consisting of cells, tissues, organs, and organ systems.

Energy Processing
The California condor (Gymnogyps californianus) uses chemical energy derived from food to power flight.

Polar bears (Ursus maritimus) and other mammals living in ice-covered regions maintain their body temperature by generating heat and reducing heat loss through thick fur and a dense layer of fat under their skin.

All molecules, including this DNA molecule, are composed of atoms.

Biological Levels of Organization
The biological levels of organization of living things follow a hierarchy, such as the one shown.From a single organelle to the entire biosphere, living organisms are parts of a highly structured hierarchy.

Phylogenetic Tree of Life
This phylogenetic tree was constructed by microbiologist Carl Woese using data obtained from sequencing ribosomal RNA genes.The tree shows the separation of living organisms into three domains: Bacteria, Archaea, and Eukarya.Bacteria and Archaea are prokaryotes, single-celled organisms lacking intracellular organelles.

Researchers work on excavating dinosaur fossils at a site in Castellón, Spain.

Forensic Science
This forensic scientist works in a DNA extraction room at the U.S. Army Criminal Investigation Laboratory at Fort Gillem, GA.

•  Wiktionary. “gene.” CC BY-SA 3.0 http://en.wiktionary.org/wiki/gene
•  Wiktionary. “phototaxis.” CC BY-SA 3.0 http://en.wiktionary.org/wiki/phototaxis
•  Wiktionary. “chemotaxis.” CC BY-SA 3.0 http://en.wiktionary.org/wiki/chemotaxis
•  CONNEXIONS. “Themes and Concepts of Biology.” CC BY 3.0 http://cnx.org/content/m44388/latest/?collection=col11448/latest
•  Wikipedia. “Adaptation.” CC BY-SA 3.0 http://en.wikipedia.org/wiki/Adaptation
•  Connexions. “Themes and Concepts of Biology.” CC BY 3.0 http://cnx.org/content/m44388/latest/?collection=col11448/latest
•  Wiktionary. “polymerization.” CC BY-SA 3.0 http://en.wiktionary.org/wiki/polymerization
•  Wiktionary. “macromolecule.” CC BY-SA 3.0 http://en.wiktionary.org/wiki/macromolecule
•  Wiktionary. “molecule.” CC BY-SA 3.0 http://en.wiktionary.org/wiki/molecule
•  Connexions. “Themes and Concepts of Biology.” CC BY 3.0 http://cnx.org/content/m44388/latest/?collection=col11448/latest
•  Wiktionary. “extremophile.” CC BY-SA 3.0 http://en.wiktionary.org/wiki/extremophile
•  Wiktionary. “DNA.” CC BY-SA 3.0 http://en.wiktionary.org/wiki/DNA
•  Wiktionary. “phylogeny.” CC BY-SA 3.0 http://en.wiktionary.org/wiki/phylogeny
•  Connexions. “Themes and Concepts of Biology.” CC BY 3.0 http://cnx.org/content/m44388/latest/?collection=col11448/latest
•  Wiktionary. “genetic engineering.” CC BY-SA 3.0 http://en.wiktionary.org/wiki/genetic+engineering
•  Wiktionary. “forensic.” CC BY-SA 3.0 http://en.wiktionary.org/wiki/forensic

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