Chapter 19 - Chromatin DNA PackagingDNA Packaging histone proteinhistone protein NucleosomeNucleosome ”beads on a string” basic unit of DNA packing”beads on a string” basic unit of DNA packing HeterochromatinHeterochromatin highly condensed interphase DNAhighly condensed interphase DNA (can not be transcribed)(can not be transcribed) EuchromatinEuchromatin less compacted interphase DNA (can be transcribed)less compacted interphase DNA (can be transcribed)

Chromatin - complex of DNA and proteins

Chapter 20 n DNA Technology & Genomics

Recombinant DNA n Def: DNA in which genes from 2 different sources are linked n Genetic engineering: direct manipulation of genes for practical purposes n Biotechnology: manipulation of DNA or organisms to perform practical tasks or provide useful products

Bacterial plasmids in gene cloning

DNA Cloning n Restriction enzymes (endonucleases): –in nature, these enzymes protect bacteria from intruding DNA; they cut up the DNA (DNA scissors) very specific n Restriction site: –recognition sequence for a particular restriction enzyme n Restriction fragments: –segments of DNA cut by restriction enzymes in a reproducable way n Sticky end: –short extensions of restriction fragments n DNA ligase: –enzyme that can join the sticky ends of DNA fragments n Cloning vector: –DNA molecule that can carry foreign DNA into a cell and replicate there (usually bacterial plasmids)

Restriction Enzymes (Endonucleases)

Steps for eukaryotic gene cloning n Isolation of (bacterial plasmid / cloning vector) & gene-source DNA (gene of interest) n Insertion of DNA into the cloning vector using the same restriction enzyme; bind the fragmented DNA with DNA ligase n Introduction of cloning vector into cells (transformation by bacterial cells) n Cloning of cells (and foreign genes) n Identification of cell clones

Cloning

DNA Analysis & Genomics n PCR (polymerase chain reaction) n Gel electrophoresis n Restriction fragment analysis (RFLPs) n Southern blotting n DNA sequencing n Human genome project

Polymerase chain reaction (PCR) n Amplification of any piece of DNA without cells (in vitro) n Materials: heat, DNA polymerase, nucleotides, single- stranded DNA primers n Applications: fossils, forensics, prenatal diagnosis, etc.

DNA Analysis n Gel electrophoresis: separates nucleic acids or proteins on the basis of size or electrical charge creating DNA bands of the same length

Restriction fragment analysis n Restriction fragment length polymorphisms (RFLPs) n Southern blotting: process that reveals sequences and the RFLPs in a DNA sequence n DNA Fingerprinting

DNA Sequencing n Determination of nucleotide sequences (Sanger method, sequencing machine) n Genomics: the study of genomes based on DNA sequences n Human Genome Project

Practical DNA Technology Uses n Diagnosis of disease n Human gene therapy n Pharmaceutical products (vaccines) n Forensics n Animal husbandry (transgenic organisms) n Genetic engineering in plants n Ethical concerns?

FISH Technique Fluorescence In Situ Hybridization

O.J. Simpson murder case Odds of blood in Ford Bronco not being R. Goldman’s: 6.5 billion to 1 Odds of blood on socks in bedroom not being N. Brown-Simpson’s: 8.5 billion to 1 Odds of blood on glove not being from R. Goldman, N. Brown-Simpson, and O.J. Simpson: 21.5 billion to 1 Number of people on planet earth: 7+ billion Odds of being struck by lightning in the U.S.: 2.8 million to 1 Odds of winning the Ohio lottery: 76 million to 1 Odds of getting killed driving to the gas station to buy a lottery ticket 4.5 million to 1 Odds of seeing 3 albino deer at the same time: 85 million to 1 Odds of having quintuplets: 85 million to 1 Odds of being struck by a meteorite: 10 trillion to 1