Summer 2008 Workshop in Biology and Multimedia for High School Teachers

Summer 2008 Workshop Melissa Marchacos Marlborough High School Bacterial Genetics

Life Sciences-HHMI Outreach. Copyright 2008 President and Fellows of Harvard College. Central Dogma Recall a “new” old dogma: DNARNAProtein Small Molecules Referenced from Dr. Jon Clary “An Ecological Approach to Microbes and Disease” Harvard University, Cambridge

Mechanisms of Genetic Transfer 1.Transformation A.The uptake of “naked” DNA from the surrounding environment 1.Free DNA (histones absent) 2.Plasmid DNA Life Sciences-HHMI Outreach. Copyright 2008 President and Fellows of Harvard College. b a+a+ Donor microbe Lysis DNA fragmentsRecipient microbeRecombinant Recipient takes up fragment Recombination b+ aa+ b a+a+

2.Transduction A.Viruses that infect bacteria; utilize syringe like mechanism to introduce genome Mechanisms of Genetic Transfer Life Sciences-HHMI Outreach. Copyright 2008 President and Fellows of Harvard College.

Life Sciences-HHMI Outreach. Copyright 2008 President and Fellows of Harvard College. Transduction, cont. Bacteriophages replicate in two manners 1.Lytic: T4 bacteriophages, bacteriophages force host to burst, releasing new bacteriophages 2.Lysogenic: incorporates genome into host genome; replicates fairly harmlessly with host

Mechanisms of Genetic Transfer 3.Conjugation A.The exchange of a plasmid B.Usually occurs between same or very similar species C.Utilizes a pilus to connect the two microbes Life Sciences-HHMI Outreach. Copyright 2008 President and Fellows of Harvard College.

Conjugation, cont. Plasmids A.Small, double stranded, circular pieces of DNA B.Replicate independently (self-replication) or within the host genome (episomes) Types of plasmids 1.Conjugative plasmids: transmitted during conjugation, carry a variety of information 2.R plasmids: resistance plasmids; protect against environmental factors, MDR (multiple drug resistance) plasmid 3.Hfr plasmids: promotes genomic recombination 4.Col-plasmids: codes for proteins that kill other microbes 5.Degradative plasmids: contain sequencing that allows host to digest uncommon substances (ex: toluene, salicylic acid) 6.Virulence plasmids: codes for altering the microbe into a pathogen

Mutation Types of mutations 1.Deletion 2.Insertion sequences (transposons) 3.Frameshift mutations 4.Silent mutations 5.Missense mutations 6.Nonsense mutations 7.Mutagen induced

References 1.Campbell, Biology, 7e; Indiana University school of Medicine; tm tm 3.University of Miami Department of Molecular and Cellular Biology; 4. Wikipedia; Life Sciences-HHMI Outreach. Copyright 2008 President and Fellows of Harvard College.