5 basic properties which serve to define life
Cellular organization, Metabolism,homeostasis, growth and reproduction, and heredity
a tiny compartment with a thin covering called a membrane. Some cells are simple while others are complex
5 organization levels of hierarchy in the cellular level
Atoms, molecules, macromolecules, organelles, cells
complex biological molecules are assembled into tiny compartments within cells called organelles. The nucleus is an organelle within which the cell's DNA is stored
grouped tissues, body structures composed of several different tissues grouped together in a structural and functional unit
all the populations of a particular kind of organism together form a ____, its members similar in appearance and able to interbreed.
highest tier, a biological community and the soil and water within which it lives together = ecological system
result from the way components interact, and often cannot be guessed just by looking at the parts themselves, properties that were not present at the simpler level of organization.
5 biological themes
evolution, the flow of energy, cooperation, structure determines function, and homeostasis
The flow of energy
all of the energy used by most organisms comes from the sun and is passed in one direction through ecosystems
Symbiosis: organisms of two different species that live in direct contact, form a type of relationship
the high degree of specialization we see among complex organisms is only possible because these organisms act to maintain a relatively stable internal environment
History of evolution
Charles Darwin was an English naturalist who, in 1859, proposed the idea that this change is a result of a process called Natural selection
Those organisms whose characteristics make them better able to survive the challenges of their environment live to reproduce, passing their favorable characteristics onto their offspring.
Making individual decisions by applying a guide of accepted general principles, using general principles to explain specific observations
6 steps of the scientific process
1. observation 2. hypothesis 3. predictions 4. testing 5. controls 6. conclusion
The four theories that unify science as biology
the cell theory, the gene theory, the theory of evolution, and the theory of heredity
The cell theory
1. All organisms are made up of cells 2. All cells must come from pre-existing cells. 3. The cell is the basic unit of all living things.
The gene theory
DNA coded in genes contains the blueprint for protein expression and proteins are the foundation for cellular structure and function
the theory of evolution
advanced by Charles Darwin in 1859, attributes the diversity of the living world to natural selection. Those organisms best able to respond to the challenges of living will leave more offspring, and this their traits become more common in the population.
the theory of heredity
first advanced by Gregor Mendel in 1865 states that the genes of an organism are inherited as discrete units
o All substances are composed of tiny particles called atoms. Every atom is composed of a positively charged nucleus around which orbit negative electrons. The electrons determine how an atom will interact with other atoms. Most atoms also contain electrically neutral particles called neutrons.
o Atoms, the smallest particles into which a substance can be divided. Are composed of electrons orbiting a nucleus composed of protons and neutrons. Electrons determine the chemical behavior of atoms.
Ions and Isotopes
o An atom with an unequal number of protons and electrons is an ion. An ion can be positively charged or negatively charged. Atoms with the same number of protons but different numbers of neutrons are isotopes.
o When an atom gains of loses one or more electrons, it is called an ion. Isotopes of an element differ in the number of neutrons they contain, but all have the same chemical properties.
o Atoms are linked together into molecules, joined by chemical bonds. There are three types of chemical bonds: ionic bonds where oppositely charged ions are attracted to each other; covalent bonds, where bonds form by the sharing of electrons; and hydrogen bonds, where polar molecules are attracted by opposite partial charges on different molecules.
o Molecules are atoms linked together y chemical bonds. Ionic bonds, covalent bonds, and hydrogen bonds are the three principal types of bonds, and van Der Waals interactions are weaker forces.
Hydrogen bonds give water unique properties
o Water forms weak chemical associations called hydrogen bonds that are responsible for much of the organization of living chemistry
o Water molecules form a network of hydrogen bonds in liquid and dissolve other polar molecules. Many of the key properties of water arise because it takes considerable energy to break liquid water's many hydrogen bonds.
o Water molecules dissociate, forming low concentrations of hydrogen and hydroxide ions. The concentration of hydrogen ions in solution is measured as pH. Buffers control the pH of a solution by regulating the concentration of hydrogen ions in the solution
o A tiny fraction of water molecules spontaneously ionize at any moment, forming H+ and OH-. The pH of a solution is a measure of its H+ concentration. Low pH values indicate high H+ concentration (acidic solutions), and high pH values indicate low H+ concentration (basic solutions).
The invention of the Linnaean system
o Biologists name organisms using a two word "binomial" system
o Two part (binomial) Latin names, first used by Linnaeus, are now universally employed by biologists to name particular organisms.
o Every kind of organism is assigned a unique Latin name
o By convention, the first part of a binomial species name identifies the genus to which the species belongs, and the second part distinguishes that particular species from other species in the genus
o The higher groups into which an organism is placed reveal a great deal about the organism
o A hierarchical system is used to classify organisms, in which higher categories convey more general information about the group.
What is a species
o Species are groups of similar organisms. Animal species tend not to interbreed with individuals of other species, while plants often do so.
o Among animals species are generally defined as reproductively isolated groups; among the other kingdoms such a definition is less useful, as their species typically have weaker barriers to hybridization.
How to build a family tree
o Traditional and cladistic interpretations of an organisms evolutionary history differ in the emphasis they place on key traits
o A phylogeny may be represented as a cladogram based on the order in which groups evolved or as a traditional taxonomic tree that weights characters according to assumed importance
The kingdoms of life
o Living organisms are placed into three large groups called domains, and within domains they are placed in to kingdoms
o Living organisms are grouped into three categories called domains. One of the domain, eukarya, is divided into four kingdoms: protista, fungi, plante, and animalia
o The prokaryotes in this domain are more numerous than any other organism
o Bacteria are as different from Archaea as they are from eukaryotes
o This domain consists of primitive prokaryotes that often live in extreme environments
o Archaea are unique prokaryotes that inhabit diverse environments, some of them extreme
o There are four kingdoms of eukaryotes, all characterized by complex cellular interiors, and three of them are entirely or predominantly multicellular.
o Eukaryotic cells acquired mitochondria and chloroplasts by endosymbiosis. The organisms in the domain Eukarya are divided into four kingdoms: fungi, plants, animals, and protists.