Plasmid is a small, circular, double-stranded DNA molecule that is distinct from a cell's chromosomal DNA. Plasmids naturally exists in bacterial cells, and they also occur in some eukaryotes. The genes carried in plasmids provide bacteria bacteria with genetic advantages, such as antibiotic resistance. To know whether the cell carry recombinant plasmids; only cells with a plasmid will reproduce and also the color of the colonies in E. coli plasmid recombination experiments allows scientists to distinguish colonies with recombinant plasmids from those without.
B. New substances are formed. In a chemical reaction, the starting molecule must be changed or turn into another. For example: rusts that form in a tin can is a chemical reaction. The iron in the can combines with the oxygen in the atmosphere, creating rust (iron oxide), which is a different substance.
A diploid cell contains two complete sets of chromosomes, while a haploid cell only one set.
