bacterial genetics supplemental instruction designed by pyeongsug kim ©2010...
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Bacterial GeneticsBacterial GeneticsSupplemental instruction
Designed by Pyeongsug Kim ©2010 [email protected]
Fall 2010For Dr. Wright’s Bio 7/27 Class
Picture from http://www.buildinggreentv.com/node/7088 http://steveaoki.dimmak.com/blog/2009/11/useless-information-4-bacteria/ http://www.scienceclarified.com/As-Bi/Bacteria.html
Designed by Pyeongsug Kim, ©2009Picture from Dr. Wright’s Bio27 Slides
___________: Duplication of a DNA molecule.; its encoded information can be passed on to future generation.
___________: synthesis of RNA from a DNA template.
___________: formation of a protein (amino acid sequence) from RNA sequence.
Transcription
Translation
Replication
Designed by Pyeongsug Kim, ©2009
Bacterial genomeBacterial genome
Picture from http://en.wikipedia.org/wiki/Plasmid http://scienceprofonline.googlepages.com/microbiologymicrobialgenetics
Many bacteria have…..• Single, circular DNA
• Plasmids Small, circular double-stranded DNA Can encode a variety of genes not essential bacterial genes may give new properties conjugation
• Operons a group of genes expressed together a functioning unit of DNA sequence -promoter -operator -structural genes
Designed by Pyeongsug Kim, ©2009
•Repressor binds to operator blocks transcription. •Corepressor binds to the repressor alters its shape enabling the repressor to bind to the operator. Transcription OFF!
•Inducer binds to the repressor alters its shape preventing the repressor to bind to the operator. Transcription ON!
Picture from Dr. Wright’s Bio27 Slides
Designed by Pyeongsug Kim, ©2009
Lactose operonLactose operon (lac operon) (lac operon)
-inducible operon -Lactose as a inducer. -Genes are expressed(turn on) only if lactose(inducer) is present.
If Lactose present genes are expressed. transcription on!
If Lactose is absent genes are not expressed. transcription off!
Designed by Pyeongsug Kim, ©2009
TryptophanTryptophan operon operon (trp operon)(trp operon)
-Repressible operon -Tryptophan as a corepressor. -Genes are not expressed(turn off) if tryptophan(corepressor) is present.
Picture from http://departments.oxy.edu/biology/bio130/lectures_2000/11-17-00_lecture.htm
MutationsMutations(rare)(rare)
-One or more amino acid is changed as a result. Bases (nucleotides) are changed or substituded-may be induced by radiation or chemical(mutanogens).
-Mutations can have a significant effect on genetic diversity.-New traits acquisition of resistance can be transmitted to other microbes.-Antimicrobial (Drug) Resistance
Designed by Pyeongsug Kim, ©2009Picture from http://www3.niaid.nih.gov/topics/antimicrobialResistance/Understanding/mutation.htm http://www.medem.com/?q=medlib/article/ZZZEY2V5BRC
Bacteria proliferate rapidly by binary fission.
Designed by Pyeongsug Kim, ©2009
MutagensMutagens -Chemicals or radiation that changes the genetic material induced mutation• Base analogs -incorporated into DNA replace normal base with base analog(similar base) Base substitution• Intercalating agents -inserted(intercalated) b/w base pairs replace normal base with base analog -Frame shift mutation addition or subtraction of base pairs• Transposons -Random insertion into any gene. The gene inactivated. -Common in lab.
MutagensMutagens (cont’d) (cont’d)
-Radiation UV ~base subsitution
X Rays ~deletion of base
Designed by Pyeongsug Kim, ©2009Picture from http://en.wikipedia.org/wiki/Radiation
Ames test Ames test -uses bacteria to test chemicals…. “Is this chemical mutagen? Carcinogens?”-more rapid and inexpensive-More colonies than control plate (than normal) “This is mutagen!”
Designed by Pyeongsug Kim, ©2009Picture from Dr. Wright’s Bio27 Slides
Gene transmission in bacteriaGene transmission in bacteria
Designed by Pyeongsug Kim, ©2009
transformation, transduction and conjugation
____________ - uptake of “naked” DNA
____________- by bacteriophages
____________- bacterial cells come in direct contact with each other. - Plasmid is often transferred
Transformation
Transduction
Conjugation
Picture from http://cwx.prenhall.com/brock/chapter9/medialib/Image3.gif
Designed by Pyeongsug Kim, ©2009Picture from Dr. Wright’s Bio27 Slides http://www.nature.com/nrm/journal/v2/n7/box/nrm0701_538a_BX1.html
AB C
TransductionTransductionConjugation
A:B:C:
B
TransformationConjugationTransduction
Designed by Pyeongsug Kim, ©2009Picture from http://faculty.irsc.edu/FACULTY/TFischer/micro%20resources.htm
A
A:B:C:
C
Designed by Pyeongsug Kim, ©2009
Picture from http://www.biotechlearn.org.nz/themes/dna_lab/images/bacterial_transformation
Transformation, Transduction and Conjugation
Which one can be performed in Laboratory?
ALL
Which one can cause antibiotic resistace?
ALL