BIO 110: Chapter 8 Biodiversity

Biogenesis

The principle that all life arises by the reproduction of preexisting life.

Bacilli

A rod-shaped prokaryotic cell.

Binary Fission

A means of asexual reproduction in which a parent organism, often a single cell, divides into two individuals of about equal size.

Biofilms

A surface-coating cooperative colony of prokaryotes and perhaps some microscopic eukaryotes.

Capsule

A dense layer of polysaccharide or protein that surrounds the cell wall of some prokaryotes and is sticky, protecting the cell and enabling it to adhere to substrates or other cells.

Cocci

A spherical prokaryotic cell.

Endospore

A thick-coated, protective cell produced within a prokaryotic cell exposed to harsh conditions.

Archaea

One of two prokaryotic domains of life, the other being Bacteria.

Halophiles

Prokaryotic microorganism that lives in a highly salty environment, such as the Great Salt Lake or the Dead Sea.

Methanogens

An archaean that produces methane as a metabolic waste product.

Thermophiles

A microorganism that thrives in a hot environment.

Bacteria

One of two prokaryotic domains of life, the other being Archaea.

Pathogens

A disease-causing virus or organism.

Bacteriophage

A virus that infects bacteria; also called a phage.

Conjugation

The union (mating) of two bacterial cells or protist cells and the transfer of DNA between the two cells.

Phage

A virus that infects bacteria.

Plasmid

A small ring of self-replicating DNA separate from the chromosome(s). Are found in prokaryotes and yeasts.

Sex Pilus

In bacteria, a structure that links one cell to another at the start of conjugation.

Transduction

The transfer of bacterial genes from one bacterial cell to another by a phage. (2) See signal transduction pathway.

Transformation

The incorporation of new genes into a cell from DNA that the cell takes up from the surrounding environment.

Endomembrane System

A network of organelles that partitions the cytoplasm of eukaryotic cells into functional compartments. Some of the organelles are structurally connected to each other, whereas others are structurally separate but functionally connected by the traffic of vesicles among them.

Endosymbiosis

Symbiotic relationship in which one species resides within another species. The mitochondria and chloroplasts of eukaryotic cells probably evolved from symbiotic associations between small prokaryotic cells living inside larger ones.

Eukaryotic Cells

A type of cell that has a membrane-enclosed nucleus and other membrane-enclosed organelles. All organisms except bacteria and archaea are composed of eukaryotic cells.

Algae

An informal term that describes a great variety of protists, most of which are unicellular or colonial photosynthetic autotrophs with chloroplasts. Heterotrophic and multicellular protists closely related to unicellular autotrophs are also regarded as algae.

Amoebas

A general term for a protozoan (animal-like protist) characterized by great structural flexibility and the presence of pseudopodia.

Protozoans

A protist that lives primarily by ingesting food; a heterotrophic, animal-like protist.

Seaweeds

A large, multicellular marine alga.

Slime Molds

A type of protist that has amoeboid cells.

Colonies

Collection of members of the same species, usually prokaryotes or protists, living in close contact.

Capsid

The protein shell that encloses a viral genome.

Virus

A microscopic particle capable of infecting cells of living organisms and inserting its genetic material. Have a very simple structure and are generally not considered to be alive because they do not display all of the characteristics associated with life.

AIDS

Acquired immunodeficiency syndrome; the late stages of HIV infection, characterized by a reduced number of T cells; usually results in death caused by opportunistic infections.

Emerging Virus

A virus that has appeared suddenly or has recently come to the attention of medical scientists.

HIV

The retrovirus that attacks the human immune system and causes AIDS.

Retrovirus

An RNA virus that reproduces by means of a DNA molecule. It reverse-transcribes its RNA into DNA, inserts the DNA into a cellular chromosome, and then transcribes more copies of the RNA from the viral DNA. HIV and a number of cancer-causing viruses are retroviruses.

Prion

An infectious form of protein that may multiply by converting related proteins to more prions. Cause several related diseases in different animals, including scrapie in sheep, mad cow disease, and Creutzfeldt-Jakob disease in humans.

Viroids

A plant pathogen composed of molecules of naked, circular RNA several hundred nucleotides long.