Understanding DNA and Gene Cloning: A Guide for the Curious

Two DNA arise out of one. Each daughter cell will receive a DNA molecule have the exact same nucleotide sequence as the parent. DNA polymerase travels down the DNA and produces an messenger RNA. The DNA strand separates as DNA polymerase and other proteins bind to the DNA. Nucleotides are added to the growing chain of the old strand which has been unzipped. The (A) DNA polymerase moves continueously in the direction of the unzipping and (B) DNA polyermarse moves in the opposite direction. DNA ligase join the fragments. Mutations occur during the replication, for example a T may mutate to a U. Gene Expression. In RNA polymerase generates Messenger RNA strand. The RNA polymerase connects to a recognition site. An amino acid connects to an enyzme and Transfer RNA connects to the amino acid then the amino acid and tRNA are released. The tRNA connects to the codon sugar on the mRNA as the Ribosome translates the mRNA. Each gene has a start and terminator codon. When the ribosome encounters the terminator codon the protein chain is released. A ribosome connects to the mRNA and produces a peptide chain of amino acids. The ribosome creates the protein chain with the help of tranfer RNA. There are 20 amino acids and each one has a corresponding tRNA. The tRNA, enzyme, and Amino Acid are assembled into a peptide; the ribosome reads the mRNA code and a matching tRNA links too it; as new codons are read the previous tRNA is released with the previous amino acid bond too the new amino acid; at the end of the mRNA the amino acid chain is released. RNA polymarse primes, connects at the origin, and traverses a section of DNA sugars producing a mRNA for a specific gene. mRNA is created and the ribosome creates the protein. Gene splicing. Enzymes cut the dna into fragments at specific locations called restriction sites. These enzymes are called restriction nucleases. A bacteria or phage can be used as a host. Plasmids and DNA are cut by the enyzems, the fragments are separated and recombined using DNA ligase resulting in a plasmid that contains human DNA fragments and plasmid fragments. The plasmid are reintroduced to the bacteria and grown producing the desired proteins. A bacteria contains the chromosomes, plasmid, and phila. A male bacteria uses the phila to pull in the female bacteria and injects the plasmid into the female making it male. The bacteria divide with the new dna. Cell division. The DNA unzips and forms two daughter cells. The nucleus wraps around each of the replicated DNA strands. What is interesting about cell division is that one strand replicates in the direction of the unzipping and the other replicates in the opposite direction and leaps back to the point of unzipping creating segments of replication connect by ligase.

This is the book that we ask all new undergraduates, time-slip students, high school students, and technicians to read before they start work in our lab. It is also the book I recommend to non-specialists like my father who want to know what I am doing. It is an excellent introduction.

For someone who already went through a college-level molecular biology course, Drlica's book is an especially good refresher. The book also goes into good detail on various protocols used by biochemical and mol/cell labs today.