Biology Chapter 1

archaeans (Archaea)

Unicellular organisms lacking a nucleus and lacking peptidoglycan in the cell wall. Once grouped with the bacteria, archaeans possess distinctive membrane lipids.

bacteria (Ecell theory ubacteria)

Unicellular organisms lacking a nucleus, possessing distinctive ribosomes and initiator tRNA, and generally containing peptidoglycan in the cell wall. Different bacterial groups are distinguished primarily on nucleotide sequence data.

cell theory

States that cells are the basic structural and physiologtical units of all living organisms, and that all cells come from preexisting cells.

DNA (deoxyribonucleic acid)

The fundamental hereditary material of all living organisms. In eukaryotes, stored primarily in the cell nucleus. A nucleic acid using deoxyribose rather than ribose.


An independent structural element within a protein. Encoded by recognizable nucleotide sequence, a domain often fold separately from the resto fof the protein. Similar domains can appear in a variety of differnt proteins across phylogenic groups.


In phylogenetics, the three monophyletic brances of life (Bacteria, Archaea, and Eukarya).


Two species living together, with one living inside the body (or even the cells) of the other.


Organisms whose cells contain their genetic material inside a nucleus. Includes all life other than the viruses, archaea, and bacteria.


A unit of heredity. Used here at the unit of genetic function which carries the information for a single poplypeptide or RNA.


The complete DNA sequence for a particular organism or individual.


The sum total of the chemical reactions that occur in an organism, or some subset of that total (as in respiratory metabolism).

model systems

Also known as model organisms, these include the small group of species that are the subject of extensive research. They are organisms that adapt well to laboratory situations and finding from experiments on them can apply across a broad range of species.


The basic chemical unit in nucleic acids, consisting of a pentose sugar, a phosphate group, and a nitrogen-containing base.


Any of the membrane-enclosed structures within a eukaryotic cell. Examples include the nucleus, endoplasmic reticulum, and mitochondria.


Metabolic processes, carried out by green plants, by which visible light is trapped and the energy used to synthesize compounds such at ATP and glucose.


Not a monophyletic group; as commonly used, includes the bacteria and archaeans. A term of convenience encompassing all cellular organisms that are not eukaryotes.


Long-chain polymer of amino acids with twenty different common side chains. Occurs with its polymer chain extended in fibrous proteins, or coiled into a compact macromolecule in enzymes and other globular proteins.