A CLOSER LOOK AT GENES AND GENETIC ENGINEERING In the United States most commercially grown corn is genetically modified Adam Gault OJO Images Getty Images
INTRODUCTION I paired chromosomes with one set inher ited from each parent When cells reproduce chromosomes carry genetic information from the parent cell to the newly produced daughter cells Most cells reproduce through a process called mito sis In mitosis One cell divides into two exact copies of itself But gametes sex cells duplicate through mei osis which involves two cell divisions The first division produces two daughter cells with a full set of chromosomes In the second division however the chromo somes do not duplicate resulting in four daugh ter cells with only half as many chromosomes The full set of chromo somes is restored when
A Closer Loo AT GENES AND GENETIC ENGINEERINC a male gamete or sperm combines with a female gamete or egg during fertilization When defects occur in the genetic mate rial diseases known as genetic disorders result The cause can be mutations or altera tions in the DNA sequence of a single gene or defects in an entire chromosome Single gene disorders result from one or more mutations in a single gene that prevent it from acting properly Chromosome disorders occur from structural defects in a chromosome or from having too many or too few chromosomes Down's syndrome for example arises in peo ple with an extra chromosome 21 Genetic engineering involves the artificial manipulation of genes to change an organism Biologists first began experimenting with this process in the 1960s Initially genetic engineering referred to any method used for modifying organisms though heredity and reproduction This included artificial insemi nation and selective breeding In modern science however the term refers specifically to the field of recombinant DNA technol ogy In this process DNA from at least two sources is combined and then inserted into a host organism There the inserted DNA rep licates and functions along with the DNA of the host Io
INTRODUCTION Although some people worry that genetic engineering could have dangerous conse quences others tout its benefits including the creation of safer vaccines This debate will undoubtedly continue Nevertheless genetic engineering will remain an essential focus of genetics and further study will only expand its uses in agriculture medicine and other areas II
