New User Special Price Expires in

Let's log you in.

Sign in with Facebook


Don't have a StudySoup account? Create one here!


Create a StudySoup account

Be part of our community, it's free to join!

Sign up with Facebook


Create your account
By creating an account you agree to StudySoup's terms and conditions and privacy policy

Already have a StudySoup account? Login here

PCB3063: Chapter 6

by: Brittany Woody

PCB3063: Chapter 6 PCB3603

Brittany Woody

Preview These Notes for FREE

Get a free preview of these Notes, just enter your email below.

Unlock Preview
Unlock Preview

Preview these materials now for free

Why put in your email? Get access to more of this material and other relevant free materials for your school

View Preview

About this Document

These are notes from the powerpoint and lecture for Chapter 6. They are supplemented with information from the textbook. Concepts of Genetics 11th Edition
Dr. W. Brad Barbazuk
Class Notes
25 ?




Popular in Genetics

Popular in Genetics

This 5 page Class Notes was uploaded by Brittany Woody on Tuesday September 20, 2016. The Class Notes belongs to PCB3603 at University of Florida taught by Dr. W. Brad Barbazuk in Fall 2016. Since its upload, it has received 18 views. For similar materials see Genetics in Genetics at University of Florida.

Similar to PCB3603 at UF


Reviews for PCB3063: Chapter 6


Report this Material


What is Karma?


Karma is the currency of StudySoup.

You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!

Date Created: 09/20/16
Chapter 6 Bacterial and Phage Genetics - Bacteria grow rapidly; spontaneous mutation is considered the primary source of genetic variation in bacteria - Bacteria have 3 growth phases: lag phase (initial, slow), log phase (rapid with a fixed time interval that results in exponential growth), stationary phase (nutrients limit growth) - Bacteria are grown in liquid culture or on a semi-solid surface (agar) - “minimal medium” contains an organic carbon source (glucose) and various inorganic ions (K+, Na+, Mg(2+), NH4+,Ca (2+)) - Growth on this medium requires the bacteria to synthesize all essential organic compounds; all bacteria that can do this are prototrophs; bacteria that lose the ability to synthesize one or more essential organic compound (through mutation) is an auxotroph - Bacteria can be counted by serial dilution; can establish populations of genetically identical bacteria by plating the appropriate dilution - Bacteria undergo conjugation, in which genetic information from one bacterium is transferred to another, and it recombines with the second bacterium’s DNA; this provides the basis for chromosome mapping methodology; the genetic recombination in bacteria (and phage) involves the replacement of one or more genes in one bacterial strain with those from a genetically distinct strain - Lederberg and Tatum experimented with multiples autotroph strains; it was highly improbable that any of the cells containing 2 or 3 mutant genes would undergo spontaneous mutation to become wild type cells, so they proposed genetic recombination had occurred - Conjugation: certain strains of bacteria were able to affect a unidirectional transfer of genetic material - In bacterial conjugation in E. coli, F+ cells serve as DNA donors and F- cells are the recipients - F+ cells contain a fertility factor (F factor) that confers the ability to donate DNA during conjugation 1 - Recipient cells are converted to F+; this requires cell to cell contact - Physical contact is required for conjugation; conjugation is mediated by a sex pilus, which is a microscopic tubular extension of the cell; results in transfer of a mobile element- which is a small piece of circular DNA; recipient F- cells become F+ cells - F factor is a plasmid; it contains about 40 genes, most of which are involved in the transfer of genetic material - An Hfr (high-frequency recombination) strain undergoes recombination 1000x more frequently than the original F+ strains; Hfr has the F factor integrated; an Her strain can donate genetic information to an F- cell, but the recipient does not become F+ - In a given Hfr strain, certain genes are more frequently recombined than others (nonrandom) - Interrupted mating demonstrated that specific genes in an Her strain are transferred and recombined sooner than others - Time mapping: the observation of a time dependent, ordered transfer of genes suggests a metric for mapping; gene order and distance (in minutes) could be determined - Other Hfr strains also transferred genes linearly with time, but the order in which genes entered the recipient cell varied from strain to strain - Gene transfer by Hfr strains led to the understanding that the E. coli chromosome is circular - If the point of origin (O) varies between strains, then a different sequence of genes will be transferred in each case - The position of the F factor determines initial point of transfer; direction of transfer is determined by the orientation of the F factor; genes adjacent to O are transferred first; F factor becomes the last part that can be transferred - Recipient cells are usually not converted to F+ because conjugation does not often last long enough to transfer the whole genome - In some cases, an F factor is excised from the chromosome of an Hfr strain; in the process, the F factor (referred to as F’) often brings several adjoining genes with it; transfer of an F’ to an F- cell results in a partially diploid cell called a merozygote - RecA protein plays an important role in recombination involving single-strand displacement 2 - The RecBCD protein is important for unwinding a double-stranded DNA molecule that serves as the source for genetic recombination, RecA then facilities recombination - Plasmids contain one or more genes and replicate independently of the bacterial chromosome; F factors confer fertility - R plasmids confer antibiotic resistance; rtf is a resistance transfer factor, and r- determinants convey resistance - Col plasmids encode colicins that can kill neighboring bacteria - In transformation, small pieces if extracellular DNA are taken up by a living bacterial cell and integrated stably into the chromosome; once it is integrated into the chromosome, the recombinant region contains one host strand (present originally) and one mutant strand; because these strands are from different sources, this region is referred to as a heteroduplex; the two strands of DNA are not perfectly complementary in this region - Ideally exogenous DNA consists of 10-20K bp, this size is sufficient to encode several genes - Genes that are close enough to each other to be cotransformed are linked - If two genes are unlinked, simultaneous transformation requires 2 distinct recombination events requiring two distinct segments of DNA - Bacteriophages can infect a host bacterium by injecting their DNA; this DNA serves as a template for the infected bacterium to produce progeny phage particles, which are released when the host cell is lysed (destroyed) - The number of phages produced following the fiction of bacteria can be determined by the plaque assay • this technique entails performing serial dilutions of virally infected bacteria, which are then poured onto agar plates • by counting the number of plaques (areas clear of bacteria) on the plates, the number of phages on the original culture can be determined • a single, small, well separated plaque was produced by a single phage infecting a bacteria; subsequent release and infection (lytic cycle) results in infection of neighboring bacteria, which eventually creates a “clearing” in the lawn 3 - Lysogenyoccurs when: • the phage DNA integrates into the bacterial chromosome • it is replicated along with the chromosome • it is passed to daughter cells • Integrated phage is a prophage. - Bacteria containing a prophage are lysogenic and can grow and divide stably until viral reproduction is induced; viral reproduction is induced by chemical or uv treatment; phage that can either lyse the cell or become prophages are temperate phages - The Lederburg-Zinder experiment identified a ‘filterable agent’ as being responsible for recombination leading to prototrophs; only bacteria from LA-22 side produced prototrophs, not the LA-2 side (note the Davis U-tube prevents conjugation) - FA produced by L-22 only when grown in association with LA-22; grow L-22 on its own, then add to LA-22 – nothing is produced • Dnase has no effect • FA could not pass if pore size < phage size - In generalized transduction, bacterial DNA instead of phage DNA is packaged in a phage particle and transferred to a recipient host - In specialized transduction, a small piece of bacterial DNA is packaged along with the phage DNA - Generalized transduction results in the transfer of a large number of bacterial genes. - Specialized transduction results in transfer of only a few bacterial genes. - Like transformation, generalized transduction can be used in linkage and chromosomal mapping. - Genes that are close together are more often transduced simultaneously. - Most phage mutants affect plaque morphology or host range; the key to doing recombination studies in phage is to co-infect - When recombination occurs between genes it is “intergenic recombination” - Map units are determined as before # of recombinants / #total 4 - Because we can examine so many events in phage recombination, we isolate really rare events – even intragenic recombination (within one gene); this allows you to map mutations within genes, and provides a means to fine-structure map a locus - Benzer’s fine structure analysis had ~20,000 mutants; initial control studies were confusing because some combinations of mutations lysed E. coli K12; Benzer reasoned that during co-infection each mutant strain provided something that the other lacked; what was happening is that some mutant combinations were ‘complementing’ each other – indicating different genes - Complementation testing put each mutation into 2 groups or “complementation groups”; this indicates two genes - the rII locus was actually made up of 2 genes - Complementation testing mapped the mutant collection to each of the two genes (he called these cistrons – his definition for the smallest functional genetic unit) - Then, he crossed A-cistron mutant to other A-cistron mutations, B-cistron mutations to B-cistron mutations. - Some of the r11 mutations were actually small deletions or various parts of each ‘cistron’; the collection of these provide an overlapping set of deletions – which are very valuable for rapid placement of mutations. - Deletion testing was used to provide a rough and quick localization of each mutation Benzer studied. - A point mutation is localized in the area of a deletion if it fails to give rise to any wild- type recombinants in complementation assays. 5


Buy Material

Are you sure you want to buy this material for

25 Karma

Buy Material

BOOM! Enjoy Your Free Notes!

We've added these Notes to your profile, click here to view them now.


You're already Subscribed!

Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'

Why people love StudySoup

Jim McGreen Ohio University

"Knowing I can count on the Elite Notetaker in my class allows me to focus on what the professor is saying instead of just scribbling notes the whole time and falling behind."

Jennifer McGill UCSF Med School

"Selling my MCAT study guides and notes has been a great source of side revenue while I'm in school. Some months I'm making over $500! Plus, it makes me happy knowing that I'm helping future med students with their MCAT."

Bentley McCaw University of Florida

"I was shooting for a perfect 4.0 GPA this semester. Having StudySoup as a study aid was critical to helping me achieve my goal...and I nailed it!"

Parker Thompson 500 Startups

"It's a great way for students to improve their educational experience and it seemed like a product that everybody wants, so all the people participating are winning."

Become an Elite Notetaker and start selling your notes online!

Refund Policy


All subscriptions to StudySoup are paid in full at the time of subscribing. To change your credit card information or to cancel your subscription, go to "Edit Settings". All credit card information will be available there. If you should decide to cancel your subscription, it will continue to be valid until the next payment period, as all payments for the current period were made in advance. For special circumstances, please email


StudySoup has more than 1 million course-specific study resources to help students study smarter. If you’re having trouble finding what you’re looking for, our customer support team can help you find what you need! Feel free to contact them here:

Recurring Subscriptions: If you have canceled your recurring subscription on the day of renewal and have not downloaded any documents, you may request a refund by submitting an email to

Satisfaction Guarantee: If you’re not satisfied with your subscription, you can contact us for further help. Contact must be made within 3 business days of your subscription purchase and your refund request will be subject for review.

Please Note: Refunds can never be provided more than 30 days after the initial purchase date regardless of your activity on the site.