 3 billion base pairs of DNA and about 30,000 genes  97% of human DNA is junk, as it does not code for protein products  Of this junk, some are regulatory sequences controlling gene expressions, some are introns that interrupt genes and most are repetitive sequences that never get transcribed

 Some genetic disorders (Huntington’s disease) are caused by abnormally long stretches of tandem repeats (back-to-back repetitive sequences) within affected genes  These tandem repeats can also make up telomeres  Polymorphic regions of DNA are noncoding and vary from one region to the next

 Taking DNA from two sources and combining them  Happens naturally during viral transduction, bacterial transformation and conjugation  Transposons jumping around the genome

 Also known as biotechnology  Scientists manipulate and engineer genes in the laboratory  Genetic engineering brings about many medical uses as well as ethical issues

 Uses: ◦ Produce a protein product, like insulin ◦ Replace a nonfunctioning gene in a person’s cells with a functioning gene by gene therapy, which does not look very promising ◦ Prepare multiple copies of a gene for analysis (more genes copied, the more they can be researched) ◦ Engineer bacteria to clean up the environment (some can eat toxic waste)

 Isolate a gene (insulin)  Insert gene into a plasmid  Insert eh plasmid into a vector, a cell that will carry the plasmid  Clone the gene ◦ as bacteria reproduce through fission, plasmid and selected gene are also cloned  Identify the bacteria that contain the selected gene and harvest it from the culture

 Restriction enzymes extracted from bacteria ◦ Help bacteria protect themselves against phages  These enzymes cut DNA at specific recognition sequences, such as GAATTC  Often, these cuts are staggered, leaving single stranded sticky ends to form a temporary unit with other sticky ends

 The fragments that result from the cuts made by restriction enzymes are called restriction fragments  Common examples are EcoRI, BamHI and HindIII  Used in gene cloning

 Separates large molecules of DNA based on their movement through agarose gel in an electrical field  Smaller molecules of DNA run faster and further through the gel  DNA is negative (phosphate groups) and flows from cathode (-) to anode (+)

 Also separates proteins and amino acids  In order to run through a gel, the DNA must be cut by restriction enzymes into small enough pieces to move through the gel  DNA can be sequenced to determine the sequence of bases  Can also be used to compare other DNA samples 

 Radioactively labeled single strand of nucleic acid molecule used to tag a specific sequence in a DNA sample  The probe bonds to the complementary sequence and enables scientist to detect its location  Used to identify a person who carries an inherited genetic disorder

 Cell-free, automated technique by which a piece of DNA can be rapidly copied  Billions of copied DNA fragments can be produced within hours  The DNA piece that is to be copied is placed into a test tube with Taq polymerase (heat- stable form of DNA polymerase extracted from extremophile bacteria)

 Along with Taq polymerase, a supply of DNA nucleotides and primers are added to the test tube to promote DNA synthesis  Once DNA is amplified, these copies can be studied or used in comparison with other DNA samples

 Information regarding target DNA nucleotide sequence must be known  Size of the piece to be amplified must be very short  CONTAMINATION

 Restriction fragment is a segment of DNA that results when DNA is treated with restriction enzymes  When scientists compared junk DNA of a population, they discovered that the restriction fragment pattern is different in every individual  Differences are called RFLPs

 Pronounced “riflips”  A RFLP analysis of someone’s DNA gives a human DNA fingerprint that looks like a bar code  Everyone’s RFLP is unique, except for identical twins

 Can determine fathers in paternity suits  Can identify perps in rape and murder cases

 Introns prevent bacterium from cloning human genes ◦ Introns are long, intervening, noncoding sequences)  Bacteria cannot delete introns after transcription  In order to clone, scientists must insert a gene without introns

 In order to do this, scientists extract fully processed mRNA from cells and then use reverse transcriptase to make DNA transcripts of the RNA  The resulting DNA molecule carries the complete coding sequence of interest without introns

 Safety ◦ Much of the milk available to consumers has come from cows that were given bovine growth hormone (BGH) ◦ Vegetables have been genetically engineered to produce special characteristics in the vegetables people eat (size, taste, color)

 Privacy ◦ DNA probes are being used to create DNA chips, which are about ½ inch square and can hold personal information about someone’s genetic identity ◦ These chips can scan a person for mutations ◦ The main concern is that the information may not remain private, and insurance companies or possible employers can find out personal information