Glossary

Allele One member of a pair or series of genes that occupy a specific position on a specific chromosome. autosomal DNA The ‘non-sex’ chromosomes. Humans have 23 pairs of chromosomes, the first 22 pairs are the autosomal DNA chromosomes and the 23rd pair is the sex chromosomes, known as the female X-chromosome (or mtDNA chromosome) and the male Y-chromosome.

Biogeography A synthetic discipline that describes the distributions of living and fossil species of plants and animals across the Earth’s surface as consequences of ecological and evolutionary processes.

Chloroplast A plastid containing chlorophyll, developed only in cells exposed to the light and almost entirely limited to plant cells. Chloroplasts are minute flattened granules, usually occurring in great numbers in the cytoplasm near the cell wall. genetic markers Alleles of genes, or DNA polymorphisms, used as experimental probes to identify an individual or group of individuals. These can be a single altered nucleotide (SNiP), or sequence motif (microsatellite), pattern of altered nucleotides or DNA fingerprint.

Genome The entire complement of genetic material in a

Chromosome set. The complete set of genetic information of an organism including DNA and RNA. genotype The genetic makeup, as distinguished from the physical appearance, of an organism or a group of organisms. The combination of alleles located on homologous chromosomes that determines a specific characteristic or trait. haplotype A set of single nucleotide polymorphisms (SNiPs) that are statistically associated. Haplotype and genotype are sometimes used interchangeably to mean genetic type, though their strict biological definitions are different. isozyme Variants of the same enzyme. metagenomics The study of genomes recovered from environmental samples. The technique is to clone DNA in large fragments directly from the microorganism’s environment (such as soil) into a culturable host and conduct a sequence-based analysis on it. The hope of this new strategy is to isolate new chemical signals, new secondary metabolites, and the reconstruction of an entire genome of an uncultured organism. mitochondria A mitochondrion is an organelle or specialized part of a cell found in the cells of most eukaryotes. Mitochondria are sometimes described as ‘cellular power plants’ because their primary purpose is to manufacture adenosine triphosphate (ATP), which is used as a source of energy. The number of

Mitochondria found in different types of cells varies widely. At one end of the spectrum, the trypanosome protozoan has one large mitochondrion; by contrast, human liver cells normally have between 1000 and 2000 each. molecular clock A theoretical clock based on the assumption that the rate at which nucleotide substitutions become fixed in evolutionary lineages is approximately constant for a given DNA sequence and reflects the time since the data diverged. nucleotide The building blocks of nucleic acids, that is, DNA and RNA. Nucleotides are composed of phosphate groups, a five-sided sugar molecule, and nitrogen-containing bases. These fall into two classes, pyrimidines and purines, and are usually denoted as a four-letter code - G, guanine; A, adenine;

T, thymine; and C, cytosine.

PCR Polymerase Chain Reaction. A molecular biological method for amplifying (creating multiple copies of) DNA without using a living organism, such as Escherichia coli or yeast. PCR is commonly used in medical and biological research labs for a variety of tasks, such as the detection of hereditary diseases, the identification of genetic fingerprints, the diagnosis of infectious diseases, the cloning of genes, and paternity testing.

Phenotype The physical appearance and constitution of an individual, or a specific manifestation of a trait, such as size or eye color, that varies between individuals. Phenotype is determined to some extent by genotype, or by the identity of the alleles that an individual carries at one or more positions on the chromosomes. Many phenotypes are determined by multiple genes and influenced by environmental factors. phylogenetics The determination of the rates and patterns of change occurring in DNA in order to reconstruct the evolutionary history of genes and organisms. The aim is to infer process from pattern: the processes of organismal evolution deduced from patterns of DNA variation and processes of molecular evolution inferred from the patterns of variations in the DNA itself.

Population A group of individuals of the same species living in the same area at the same time; a stable group of randomly interbreeding individuals.

Y chromosome A chromosome is a large macromolecule into which DNA is normally packaged in a cell. It is a very long, continuous piece of DNA (a single DNA molecule), which contains many genes, regulatory elements, and other intervening nucleotide sequences. The Y chromosome is one of the two sex-determining chromosomes in humans and most other mammals (the other is the X chromosome) and determines maleness.