Appendix C: 

 Glossary 



Contigs: Groups ot clones representing overlapping regions of a genome. 



Cosmid: Artificially constructed cloning vector containing the ens gene of phage 

 lambda. Cosmids can be packaged in lambda phage particles for infection into 

 E. (v>//; this permits cloning of larger DNA fragments (up to 45 kb) than can be 

 introduced mio bacterial hosts in plasmid vectors. 



Crossing over: The breaking during meiosis of one maternal and one paternal 



chromosome, the exchange of corresponding sections of DNA. and the rejoining 

 of the chromosomes. This process can result in an e.xchange of alleles between 

 chromosomes. 



Cytosine (C): A nitrogenous base, one member of the base pair, G-C (guanine and 

 cytosine). 



C-value paradox: The lack of correlation between the amount of DNA in a haploid 

 genome and the biological complexity of the organism. (C-value refers to haploid 

 genome size.) 



Determinism: The theory that for every action taken there are causal mechanisms such 

 that no other action was possible. 



Diploid: A full set of genetic material, consisting of paired chromosomes — one 



chromosome from each parental set. Most animal cells except the gametes have a 

 diploid set of chromosomes. The diploid human genome has 46 chromosomes. 

 Compare haploid. 



DNA, deoxyribonucleic acid: The molecule that encodes genetic information. DNA is 

 a double-stranded molecule held together by weak bonds between base pairs of 

 nucleotides. The four nucleotides in DNA contain the bases: adenine (A), guanine 

 (G), cytosine (C). and thymine (T). In nature, base pairs form only between A and 

 T and between G and C: thus the sequence of each single strand can be deduced 

 from that of its partner. 



DNA probes: See probes. 



DNA replication: The use of existing DNA as a template for the synthesis of new DNA 

 strands. In humans and other eukaryotes, replication occurs in the cell nucleus. 



DNA sequence: The relative order of base pairs, whether in a fragment of DNA. a 

 gene, a chromosome, or an entire genome. See base sei/uc?ice analysis. 



Domain: A discrete portion of a protein with its own function. The combination of 

 domains in a single protein determines its overall function. 



Double helix: The shape that two linear strands of DNA assume when bonded together. 



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