Centimorgan (cM): A unit of measure of recombination frequency. One centimorgan 

 is equal to a 1 -percent chance that a marker at one genetic locus will be separated 

 from a marker at a second locus due to crossing over in a single generation. In 

 human beings. 1 centimorgan is equivalent, on average, to 1 million base pairs. 



Centromere: A specialized chromosome region to which spindle fibers attach during 

 cell division. 



Chromosomes: The autoreplicating genetic structures of ceils, containing the cellular 

 DNA that bears in its nucleotide sequence the linear array of genes. In 

 prokaryotes. chromosomal DNA is circular, and the entire genome is carried on 

 one chromosome. Eukaryotic genomes are divided between a number of 

 chromosomes in which the DNA is associated with many different kinds of 

 proteins. 



Clone bank: See Genomic library. 



Cloning: The process of asexually producing a group of cells (clones), all genetically 

 identical, from a single ancestor. In recombinant DNA technology, the u.se of 

 DNA manipulation procedures to produce multiple copies of a single gene or 

 segment of DNA is referred to as cloning DNA. 



Cloning vector: DNA molecule originating from a virus, a plasmid, or the cell of a 

 higher organism into which another DNA fragment of appropriate size can be 

 integrated without loss of the vector's capacity for self-replication; vectors 

 introduce foreign DNA into host cells, where it can be reproduced in large 

 quantities. Examples are plasmids, cosmids, and yeast artifical chromosomes; 

 vectors are often recombinant molecules containing DNA sequences from several 

 sources. 



Code: See genetic code. 



Cohesive (sticky) ends: On linear duplex DNA molecules, single-stranded ends that are 

 complementary and can base-pair either with each other to form a circular 

 molecule or with other linear DNAs having the same termini to form recombinant 

 DNA molecules. 



Colony hybridization: See in situ colony hybridization. 



Complementary DNA (cDNA): DNA that is synthesized from a messenger RNA 

 template; the single-strand form is often used as a probe in physical mapping. 



Complementary sequences: Nucleic acid sequences that can form a double-stranded 

 structure by formation of base pairs; the sequence complementary to G-T-A-C is 

 C-A-T-G. 



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