UNIT VI MOLECULAR GENETICS IV MICROBIAL GENETICS VIRUSES
UNIT VI – MOLECULAR GENETICS
IV. MICROBIAL GENETICS – VIRUSES • Discovery of Viruses Ø 1883 - Adolf Mayer discovered that _____________________________ was “contagious” because of the sap Ø Thought it was caused by a _____ Ø 1890 – Dimitri Ivanowsky passed sap from infected tobacco leaves through a filter designed to remove bacteria and found that the disease was still transmitted Ø Bacteria are so small they are getting through the filter Ø 1897 – Martinus Beijerinck discovered that the infectious agent could reproduce & it could not be
IV. VIRUSES, CONT • Not organisms; correctly referred to as _________ • Not capable of carrying out life processes without a _________ • Parasites
IV. VIRUSES, cont • Characteristics § Viral genome may be either _____-stranded or ______-stranded _______ or ____. § Protein coat surrounding virus is known as a _______ made up of protein subunits called ___________. § Some viruses are also surrounded by a ____________ Ø Typically derived from host cell membrane Ø Exception is Herpes virus, synthesized from nuclear envelope of host cell Ø Aide in __________. Envelope glycoproteins bind to receptor molecules on host cell Ø Most viruses that infect animals have envelope
IV. VIRAL INFECTION
IV. VIRAL INFECTION, cont Reproduction 1. Lytic Cycle – Results in death of host cell. LYTIC CYCL E
IV. VIRAL INFECTION, cont Reproduction LYSOGENIC CYCLE
IV. VIRAL INFECTION, cont - Retroviruses
IV. VIRUSES, cont – Animal Viruses • DNA Viruses Ø Herpesvirus § § § Herpes simplex I and II Epstein-Barr virus Varicella zoster Ø Papillomavirus • RNA Viruses Ø Ø Rhinovirus Coronavirus Ebola virus Influenza virus
IV. VIRUSES, cont – Other Infectious Agent • Viroids • Prions
V. MICROBIAL GENETICS - BACTERIA • Genetic Make-up of Bacteria § Prokaryotic § Single chromosome wrapped in much less protein than found in euks § DNA concentrated in region known as _______ • Reproduction § Haploid § Reproduce asexually through ____________ § Mutations do produce minimal genetic variation, but bacteria have developed mechanisms for genetic variability through _______________
V. MICROBIAL GENETICS - BACTERIA • ____________ Ø Ability to take up ____________ from surrounding environment Ø Used to introduce human genes into bacterial cells to produce human protein Ø “This is what you will do in lab today” • ___________ Ø Use of _________ to carry bacterial genes from one host cell to another (phages) • ___________ Ø “__________” Ø One-way transfer of a self-replication piece of DNA called a _______ Ø Donor (male) extends _____, pulls cells together, cytoplasmic bridge forms, and DNA is transferred
V. BACTERIA, cont • A Closer Look at Plasmids § Bacterium’s ability to produce plasmids and form pili due to specific piece of DNA known as the ___________ _ Ø F factor may be integrated into chromosome, or separate as a piece of plasmid Ø Contains an origin of replication Ø Copy of F factor may be transferred to recipient cell; allow recipient cell to become “male”
VI. DNA TECHNOLOGY, cont Extensions • Gene Cloning § Process of preparing multiple copies of a particular segment of DNA Ø Plasmid isolated from bacterial cell Ø Foreign DNA inserted into plasmid Ø Plasmid returned to bacterial cell; described as recombinant bacterium Ø Foreign gene is cloned as bacteria
VI. DNA TECHNOLOGY Techniques • Restriction Enzymes o Used by bacteria to _________ viral DNA o Very specific § Each enzyme recognizes a particular nucleotide sequence § Specific points § May create ________ o Used in gel electrophoresis o Also used to form recombinant DNA § Fragments may be pasted together with _______
VI. DNA TECHNOLOGY, cont Techniques • Recombinant DNA § DNA containing nucleotides from other sources § Process utilizes ____________ ___ that make jagged cuts in DNA; creates sticky ends § When DNA from different sources treated with same
VI. DNA TECHNOLOGY, cont Extensions A CLOSER LOOK AT GENE CLONING USING PLASMID S
VI. DNA TECHNOLOGY, cont Techniques • POLYMERASE CHAIN REACTION (PCR) o In vitro method of _________ _ small amounts or fragmented DNA § DNA is heated to separate the double helix. § Mixture is allowed to cool, DNA primers attach to target § Heat-stable polymerase is used to extend the primers in the 5’– 3’
VI. DNA TECHNOLOGY, cont Extensions • GEL ELECTROPHORESIS o Separates DNA fragments based on _____ o Restriction fragment analysis § DNA treated with restriction enzymes § Resulting fragments migrate based on size § Produce a pattern characteristic of original DNA and restriction enzyme used
VI. DNA TECHNOLOGY, cont - Medicine • DNA Fingerprinting – Collection of a specific pattern of DNA restriction fragments • Gene Therapy – Replacing a ________ gene with a _______ gene (disorders) • Transgenic Plants – Animals who carry ________________ from other species – Created using __________ • Transgenic Animals (aka “Pharm” Animals): – Animals who carry ________ from other species – Goals • To make animals with better quality traits (better wool, leaner meat, faster maturity) • To produce an animal that serves as a pharmaceutical “factory” by producing large amounts of rare biological substance for medical use – Example: proteins (ex. blood clotting factor) can be secreted in the animal's milk and can be more easily purified)
VI. DNA TECHNOLOGY, cont Extensions • Reproductive Cloning § ____________________ § Process of using unfertilized egg cell & replacing nucleus with DNA § In 1997, scientists were able to produce first reproductive clone, “Dolly”, by culturing somatic cells in a nutrient -poor medium to dedifferentiate them and force them back to totipotency.
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